Project import generated by Copybara.

GitOrigin-RevId: 8e1da4611d93ccb7d9674713157d43be0348d98f

docs/solutions/hands.md

@@ -220,6 +220,7 @@ import cv2
 import mediapipe as mp
 mp_drawing = mp.solutions.drawing_utils
 mp_hands = mp.solutions.hands
+drawing_styles = mp.solutions.drawing_styles
 
 # For static images:
 IMAGE_FILES = []
@@ -248,7 +249,9 @@ with mp_hands.Hands(
           f'{hand_landmarks.landmark[mp_hands.HandLandmark.INDEX_FINGER_TIP].y * image_height})'
       )
       mp_drawing.draw_landmarks(
-          annotated_image, hand_landmarks, mp_hands.HAND_CONNECTIONS)
+          annotated_image, hand_landmarks, mp_hands.HAND_CONNECTIONS,
+          drawing_styles.get_default_hand_landmark_style(),
+          drawing_styles.get_default_hand_connection_style())
     cv2.imwrite(
         '/tmp/annotated_image' + str(idx) + '.png', cv2.flip(annotated_image, 1))
 
@@ -278,7 +281,9 @@ with mp_hands.Hands(
     if results.multi_hand_landmarks:
       for hand_landmarks in results.multi_hand_landmarks:
         mp_drawing.draw_landmarks(
-            image, hand_landmarks, mp_hands.HAND_CONNECTIONS)
+            image, hand_landmarks, mp_hands.HAND_CONNECTIONS,
+            drawing_styles.get_default_hand_landmark_style(),
+            drawing_styles.get_default_hand_connection_style())
     cv2.imshow('MediaPipe Hands', image)
     if cv2.waitKey(5) & 0xFF == 27:
       break

mediapipe/calculators/core/add_header_calculator_test.cc

@@ -24,6 +24,9 @@
 
 namespace mediapipe {
 
+constexpr char kDataTag[] = "DATA";
+constexpr char kHeaderTag[] = "HEADER";
+
 class AddHeaderCalculatorTest : public ::testing::Test {};
 
 TEST_F(AddHeaderCalculatorTest, HeaderStream) {
@@ -36,11 +39,11 @@ TEST_F(AddHeaderCalculatorTest, HeaderStream) {
   CalculatorRunner runner(node);
 
   // Set header and add 5 packets.
-  runner.MutableInputs()->Tag("HEADER").header =
+  runner.MutableInputs()->Tag(kHeaderTag).header =
       Adopt(new std::string("my_header"));
   for (int i = 0; i < 5; ++i) {
     Packet packet = Adopt(new int(i)).At(Timestamp(i * 1000));
-    runner.MutableInputs()->Tag("DATA").packets.push_back(packet);
+    runner.MutableInputs()->Tag(kDataTag).packets.push_back(packet);
   }
 
   // Run calculator.
@@ -85,13 +88,14 @@ TEST_F(AddHeaderCalculatorTest, NoPacketsOnHeaderStream) {
   CalculatorRunner runner(node);
 
   // Set header and add 5 packets.
-  runner.MutableInputs()->Tag("HEADER").header =
+  runner.MutableInputs()->Tag(kHeaderTag).header =
       Adopt(new std::string("my_header"));
-  runner.MutableInputs()->Tag("HEADER").packets.push_back(
+  runner.MutableInputs()
-      Adopt(new std::string("not allowed")));
+      ->Tag(kHeaderTag)
+      .packets.push_back(Adopt(new std::string("not allowed")));
   for (int i = 0; i < 5; ++i) {
     Packet packet = Adopt(new int(i)).At(Timestamp(i * 1000));
-    runner.MutableInputs()->Tag("DATA").packets.push_back(packet);
+    runner.MutableInputs()->Tag(kDataTag).packets.push_back(packet);
   }
 
   // Run calculator.
@@ -108,11 +112,11 @@ TEST_F(AddHeaderCalculatorTest, InputSidePacket) {
   CalculatorRunner runner(node);
 
   // Set header and add 5 packets.
-  runner.MutableSidePackets()->Tag("HEADER") =
+  runner.MutableSidePackets()->Tag(kHeaderTag) =
       Adopt(new std::string("my_header"));
   for (int i = 0; i < 5; ++i) {
     Packet packet = Adopt(new int(i)).At(Timestamp(i * 1000));
-    runner.MutableInputs()->Tag("DATA").packets.push_back(packet);
+    runner.MutableInputs()->Tag(kDataTag).packets.push_back(packet);
   }
 
   // Run calculator.
@@ -143,13 +147,13 @@ TEST_F(AddHeaderCalculatorTest, UsingBothSideInputAndStream) {
   CalculatorRunner runner(node);
 
   // Set both headers and add 5 packets.
-  runner.MutableSidePackets()->Tag("HEADER") =
+  runner.MutableSidePackets()->Tag(kHeaderTag) =
       Adopt(new std::string("my_header"));
-  runner.MutableSidePackets()->Tag("HEADER") =
+  runner.MutableSidePackets()->Tag(kHeaderTag) =
       Adopt(new std::string("my_header"));
   for (int i = 0; i < 5; ++i) {
     Packet packet = Adopt(new int(i)).At(Timestamp(i * 1000));
-    runner.MutableInputs()->Tag("DATA").packets.push_back(packet);
+    runner.MutableInputs()->Tag(kDataTag).packets.push_back(packet);
   }
 
   // Run should fail because header can only be provided one way.

mediapipe/calculators/core/counting_source_calculator.cc

@@ -19,6 +19,13 @@
 
 namespace mediapipe {
 
+constexpr char kIncrementTag[] = "INCREMENT";
+constexpr char kInitialValueTag[] = "INITIAL_VALUE";
+constexpr char kBatchSizeTag[] = "BATCH_SIZE";
+constexpr char kErrorCountTag[] = "ERROR_COUNT";
+constexpr char kMaxCountTag[] = "MAX_COUNT";
+constexpr char kErrorOnOpenTag[] = "ERROR_ON_OPEN";
+
 // Source calculator that produces MAX_COUNT*BATCH_SIZE int packets of
 // sequential numbers from INITIAL_VALUE (default 0) with a common
 // difference of INCREMENT (default 1) between successive numbers (with
@@ -33,53 +40,53 @@ class CountingSourceCalculator : public CalculatorBase {
   static absl::Status GetContract(CalculatorContract* cc) {
     cc->Outputs().Index(0).Set<int>();
 
-    if (cc->InputSidePackets().HasTag("ERROR_ON_OPEN")) {
+    if (cc->InputSidePackets().HasTag(kErrorOnOpenTag)) {
-      cc->InputSidePackets().Tag("ERROR_ON_OPEN").Set<bool>();
+      cc->InputSidePackets().Tag(kErrorOnOpenTag).Set<bool>();
     }
 
-    RET_CHECK(cc->InputSidePackets().HasTag("MAX_COUNT") ||
+    RET_CHECK(cc->InputSidePackets().HasTag(kMaxCountTag) ||
-              cc->InputSidePackets().HasTag("ERROR_COUNT"));
+              cc->InputSidePackets().HasTag(kErrorCountTag));
-    if (cc->InputSidePackets().HasTag("MAX_COUNT")) {
+    if (cc->InputSidePackets().HasTag(kMaxCountTag)) {
-      cc->InputSidePackets().Tag("MAX_COUNT").Set<int>();
+      cc->InputSidePackets().Tag(kMaxCountTag).Set<int>();
     }
-    if (cc->InputSidePackets().HasTag("ERROR_COUNT")) {
+    if (cc->InputSidePackets().HasTag(kErrorCountTag)) {
-      cc->InputSidePackets().Tag("ERROR_COUNT").Set<int>();
+      cc->InputSidePackets().Tag(kErrorCountTag).Set<int>();
     }
 
-    if (cc->InputSidePackets().HasTag("BATCH_SIZE")) {
+    if (cc->InputSidePackets().HasTag(kBatchSizeTag)) {
-      cc->InputSidePackets().Tag("BATCH_SIZE").Set<int>();
+      cc->InputSidePackets().Tag(kBatchSizeTag).Set<int>();
     }
-    if (cc->InputSidePackets().HasTag("INITIAL_VALUE")) {
+    if (cc->InputSidePackets().HasTag(kInitialValueTag)) {
-      cc->InputSidePackets().Tag("INITIAL_VALUE").Set<int>();
+      cc->InputSidePackets().Tag(kInitialValueTag).Set<int>();
     }
-    if (cc->InputSidePackets().HasTag("INCREMENT")) {
+    if (cc->InputSidePackets().HasTag(kIncrementTag)) {
-      cc->InputSidePackets().Tag("INCREMENT").Set<int>();
+      cc->InputSidePackets().Tag(kIncrementTag).Set<int>();
     }
     return absl::OkStatus();
   }
 
   absl::Status Open(CalculatorContext* cc) override {
-    if (cc->InputSidePackets().HasTag("ERROR_ON_OPEN") &&
+    if (cc->InputSidePackets().HasTag(kErrorOnOpenTag) &&
-        cc->InputSidePackets().Tag("ERROR_ON_OPEN").Get<bool>()) {
+        cc->InputSidePackets().Tag(kErrorOnOpenTag).Get<bool>()) {
       return absl::NotFoundError("expected error");
     }
-    if (cc->InputSidePackets().HasTag("ERROR_COUNT")) {
+    if (cc->InputSidePackets().HasTag(kErrorCountTag)) {
-      error_count_ = cc->InputSidePackets().Tag("ERROR_COUNT").Get<int>();
+      error_count_ = cc->InputSidePackets().Tag(kErrorCountTag).Get<int>();
       RET_CHECK_LE(0, error_count_);
     }
-    if (cc->InputSidePackets().HasTag("MAX_COUNT")) {
+    if (cc->InputSidePackets().HasTag(kMaxCountTag)) {
-      max_count_ = cc->InputSidePackets().Tag("MAX_COUNT").Get<int>();
+      max_count_ = cc->InputSidePackets().Tag(kMaxCountTag).Get<int>();
       RET_CHECK_LE(0, max_count_);
     }
-    if (cc->InputSidePackets().HasTag("BATCH_SIZE")) {
+    if (cc->InputSidePackets().HasTag(kBatchSizeTag)) {
-      batch_size_ = cc->InputSidePackets().Tag("BATCH_SIZE").Get<int>();
+      batch_size_ = cc->InputSidePackets().Tag(kBatchSizeTag).Get<int>();
       RET_CHECK_LT(0, batch_size_);
     }
-    if (cc->InputSidePackets().HasTag("INITIAL_VALUE")) {
+    if (cc->InputSidePackets().HasTag(kInitialValueTag)) {
-      counter_ = cc->InputSidePackets().Tag("INITIAL_VALUE").Get<int>();
+      counter_ = cc->InputSidePackets().Tag(kInitialValueTag).Get<int>();
     }
-    if (cc->InputSidePackets().HasTag("INCREMENT")) {
+    if (cc->InputSidePackets().HasTag(kIncrementTag)) {
-      increment_ = cc->InputSidePackets().Tag("INCREMENT").Get<int>();
+      increment_ = cc->InputSidePackets().Tag(kIncrementTag).Get<int>();
       RET_CHECK_LT(0, increment_);
     }
     RET_CHECK(error_count_ >= 0 || max_count_ >= 0);

mediapipe/calculators/core/dequantize_byte_array_calculator.cc

@@ -35,11 +35,14 @@
 //   }
 namespace mediapipe {
 
+constexpr char kFloatVectorTag[] = "FLOAT_VECTOR";
+constexpr char kEncodedTag[] = "ENCODED";
+
 class DequantizeByteArrayCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->Inputs().Tag("ENCODED").Set<std::string>();
+    cc->Inputs().Tag(kEncodedTag).Set<std::string>();
-    cc->Outputs().Tag("FLOAT_VECTOR").Set<std::vector<float>>();
+    cc->Outputs().Tag(kFloatVectorTag).Set<std::vector<float>>();
     return absl::OkStatus();
   }
 
@@ -66,7 +69,7 @@ class DequantizeByteArrayCalculator : public CalculatorBase {
 
   absl::Status Process(CalculatorContext* cc) final {
     const std::string& encoded =
-        cc->Inputs().Tag("ENCODED").Value().Get<std::string>();
+        cc->Inputs().Tag(kEncodedTag).Value().Get<std::string>();
     std::vector<float> float_vector;
     float_vector.reserve(encoded.length());
     for (int i = 0; i < encoded.length(); ++i) {
@@ -74,7 +77,7 @@ class DequantizeByteArrayCalculator : public CalculatorBase {
           static_cast<unsigned char>(encoded.at(i)) * scalar_ + bias_);
     }
     cc->Outputs()
-        .Tag("FLOAT_VECTOR")
+        .Tag(kFloatVectorTag)
         .AddPacket(MakePacket<std::vector<float>>(float_vector)
                        .At(cc->InputTimestamp()));
     return absl::OkStatus();

mediapipe/calculators/core/dequantize_byte_array_calculator_test.cc

@@ -25,6 +25,9 @@
 
 namespace mediapipe {
 
+constexpr char kFloatVectorTag[] = "FLOAT_VECTOR";
+constexpr char kEncodedTag[] = "ENCODED";
+
 TEST(QuantizeFloatVectorCalculatorTest, WrongConfig) {
   CalculatorGraphConfig::Node node_config =
       ParseTextProtoOrDie<CalculatorGraphConfig::Node>(R"pb(
@@ -39,7 +42,9 @@ TEST(QuantizeFloatVectorCalculatorTest, WrongConfig) {
       )pb");
   CalculatorRunner runner(node_config);
   std::string empty_string;
-  runner.MutableInputs()->Tag("ENCODED").packets.push_back(
+  runner.MutableInputs()
+      ->Tag(kEncodedTag)
+      .packets.push_back(
           MakePacket<std::string>(empty_string).At(Timestamp(0)));
   auto status = runner.Run();
   EXPECT_FALSE(status.ok());
@@ -64,7 +69,9 @@ TEST(QuantizeFloatVectorCalculatorTest, WrongConfig2) {
       )pb");
   CalculatorRunner runner(node_config);
   std::string empty_string;
-  runner.MutableInputs()->Tag("ENCODED").packets.push_back(
+  runner.MutableInputs()
+      ->Tag(kEncodedTag)
+      .packets.push_back(
           MakePacket<std::string>(empty_string).At(Timestamp(0)));
   auto status = runner.Run();
   EXPECT_FALSE(status.ok());
@@ -89,7 +96,9 @@ TEST(QuantizeFloatVectorCalculatorTest, WrongConfig3) {
       )pb");
   CalculatorRunner runner(node_config);
   std::string empty_string;
-  runner.MutableInputs()->Tag("ENCODED").packets.push_back(
+  runner.MutableInputs()
+      ->Tag(kEncodedTag)
+      .packets.push_back(
           MakePacket<std::string>(empty_string).At(Timestamp(0)));
   auto status = runner.Run();
   EXPECT_FALSE(status.ok());
@@ -114,14 +123,16 @@ TEST(DequantizeByteArrayCalculatorTest, TestDequantization) {
       )pb");
   CalculatorRunner runner(node_config);
   unsigned char input[4] = {0x7F, 0xFF, 0x00, 0x01};
-  runner.MutableInputs()->Tag("ENCODED").packets.push_back(
+  runner.MutableInputs()
+      ->Tag(kEncodedTag)
+      .packets.push_back(
           MakePacket<std::string>(
               std::string(reinterpret_cast<char const*>(input), 4))
               .At(Timestamp(0)));
   auto status = runner.Run();
   MP_ASSERT_OK(runner.Run());
   const std::vector<Packet>& outputs =
-      runner.Outputs().Tag("FLOAT_VECTOR").packets;
+      runner.Outputs().Tag(kFloatVectorTag).packets;
   EXPECT_EQ(1, outputs.size());
   const std::vector<float>& result = outputs[0].Get<std::vector<float>>();
   ASSERT_FALSE(result.empty());

mediapipe/calculators/core/flow_limiter_calculator.cc

@@ -24,6 +24,11 @@
 
 namespace mediapipe {
 
+constexpr char kFinishedTag[] = "FINISHED";
+constexpr char kAllowTag[] = "ALLOW";
+constexpr char kMaxInFlightTag[] = "MAX_IN_FLIGHT";
+constexpr char kOptionsTag[] = "OPTIONS";
+
 // FlowLimiterCalculator is used to limit the number of frames in flight
 // by dropping input frames when necessary.
 //
@@ -69,16 +74,19 @@ class FlowLimiterCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
     auto& side_inputs = cc->InputSidePackets();
-    side_inputs.Tag("OPTIONS").Set<FlowLimiterCalculatorOptions>().Optional();
+    side_inputs.Tag(kOptionsTag).Set<FlowLimiterCalculatorOptions>().Optional();
-    cc->Inputs().Tag("OPTIONS").Set<FlowLimiterCalculatorOptions>().Optional();
+    cc->Inputs()
+        .Tag(kOptionsTag)
+        .Set<FlowLimiterCalculatorOptions>()
+        .Optional();
     RET_CHECK_GE(cc->Inputs().NumEntries(""), 1);
     for (int i = 0; i < cc->Inputs().NumEntries(""); ++i) {
       cc->Inputs().Get("", i).SetAny();
       cc->Outputs().Get("", i).SetSameAs(&(cc->Inputs().Get("", i)));
     }
     cc->Inputs().Get("FINISHED", 0).SetAny();
-    cc->InputSidePackets().Tag("MAX_IN_FLIGHT").Set<int>().Optional();
+    cc->InputSidePackets().Tag(kMaxInFlightTag).Set<int>().Optional();
-    cc->Outputs().Tag("ALLOW").Set<bool>().Optional();
+    cc->Outputs().Tag(kAllowTag).Set<bool>().Optional();
     cc->SetInputStreamHandler("ImmediateInputStreamHandler");
     cc->SetProcessTimestampBounds(true);
     return absl::OkStatus();
@@ -87,9 +95,9 @@ class FlowLimiterCalculator : public CalculatorBase {
   absl::Status Open(CalculatorContext* cc) final {
     options_ = cc->Options<FlowLimiterCalculatorOptions>();
     options_ = tool::RetrieveOptions(options_, cc->InputSidePackets());
-    if (cc->InputSidePackets().HasTag("MAX_IN_FLIGHT")) {
+    if (cc->InputSidePackets().HasTag(kMaxInFlightTag)) {
       options_.set_max_in_flight(
-          cc->InputSidePackets().Tag("MAX_IN_FLIGHT").Get<int>());
+          cc->InputSidePackets().Tag(kMaxInFlightTag).Get<int>());
     }
     input_queues_.resize(cc->Inputs().NumEntries(""));
     RET_CHECK_OK(CopyInputHeadersToOutputs(cc->Inputs(), &(cc->Outputs())));
@@ -104,8 +112,8 @@ class FlowLimiterCalculator : public CalculatorBase {
 
   // Outputs a packet indicating whether a frame was sent or dropped.
   void SendAllow(bool allow, Timestamp ts, CalculatorContext* cc) {
-    if (cc->Outputs().HasTag("ALLOW")) {
+    if (cc->Outputs().HasTag(kAllowTag)) {
-      cc->Outputs().Tag("ALLOW").AddPacket(MakePacket<bool>(allow).At(ts));
+      cc->Outputs().Tag(kAllowTag).AddPacket(MakePacket<bool>(allow).At(ts));
     }
   }
 
@@ -155,7 +163,7 @@ class FlowLimiterCalculator : public CalculatorBase {
     options_ = tool::RetrieveOptions(options_, cc->Inputs());
 
     // Process the FINISHED input stream.
-    Packet finished_packet = cc->Inputs().Tag("FINISHED").Value();
+    Packet finished_packet = cc->Inputs().Tag(kFinishedTag).Value();
     if (finished_packet.Timestamp() == cc->InputTimestamp()) {
       while (!frames_in_flight_.empty() &&
              frames_in_flight_.front() <= finished_packet.Timestamp()) {
@@ -210,8 +218,8 @@ class FlowLimiterCalculator : public CalculatorBase {
       Timestamp bound =
           cc->Inputs().Get("", 0).Value().Timestamp().NextAllowedInStream();
       SetNextTimestampBound(bound, &cc->Outputs().Get("", 0));
-      if (cc->Outputs().HasTag("ALLOW")) {
+      if (cc->Outputs().HasTag(kAllowTag)) {
-        SetNextTimestampBound(bound, &cc->Outputs().Tag("ALLOW"));
+        SetNextTimestampBound(bound, &cc->Outputs().Tag(kAllowTag));
       }
     }
 

mediapipe/calculators/core/flow_limiter_calculator_test.cc

@@ -36,6 +36,13 @@
 namespace mediapipe {
 
 namespace {
+
+constexpr char kDropTimestampsTag[] = "DROP_TIMESTAMPS";
+constexpr char kClockTag[] = "CLOCK";
+constexpr char kWarmupTimeTag[] = "WARMUP_TIME";
+constexpr char kSleepTimeTag[] = "SLEEP_TIME";
+constexpr char kPacketTag[] = "PACKET";
+
 // A simple Semaphore for synchronizing test threads.
 class AtomicSemaphore {
  public:
@@ -204,17 +211,17 @@ TEST_F(FlowLimiterCalculatorSemaphoreTest, FramesDropped) {
 class SleepCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->Inputs().Tag("PACKET").SetAny();
+    cc->Inputs().Tag(kPacketTag).SetAny();
-    cc->Outputs().Tag("PACKET").SetSameAs(&cc->Inputs().Tag("PACKET"));
+    cc->Outputs().Tag(kPacketTag).SetSameAs(&cc->Inputs().Tag(kPacketTag));
-    cc->InputSidePackets().Tag("SLEEP_TIME").Set<int64>();
+    cc->InputSidePackets().Tag(kSleepTimeTag).Set<int64>();
-    cc->InputSidePackets().Tag("WARMUP_TIME").Set<int64>();
+    cc->InputSidePackets().Tag(kWarmupTimeTag).Set<int64>();
-    cc->InputSidePackets().Tag("CLOCK").Set<mediapipe::Clock*>();
+    cc->InputSidePackets().Tag(kClockTag).Set<mediapipe::Clock*>();
     cc->SetTimestampOffset(0);
     return absl::OkStatus();
   }
 
   absl::Status Open(CalculatorContext* cc) final {
-    clock_ = cc->InputSidePackets().Tag("CLOCK").Get<mediapipe::Clock*>();
+    clock_ = cc->InputSidePackets().Tag(kClockTag).Get<mediapipe::Clock*>();
     return absl::OkStatus();
   }
 
@@ -222,10 +229,12 @@ class SleepCalculator : public CalculatorBase {
     ++packet_count;
     absl::Duration sleep_time = absl::Microseconds(
         packet_count == 1
-            ? cc->InputSidePackets().Tag("WARMUP_TIME").Get<int64>()
+            ? cc->InputSidePackets().Tag(kWarmupTimeTag).Get<int64>()
-            : cc->InputSidePackets().Tag("SLEEP_TIME").Get<int64>());
+            : cc->InputSidePackets().Tag(kSleepTimeTag).Get<int64>());
     clock_->Sleep(sleep_time);
-    cc->Outputs().Tag("PACKET").AddPacket(cc->Inputs().Tag("PACKET").Value());
+    cc->Outputs()
+        .Tag(kPacketTag)
+        .AddPacket(cc->Inputs().Tag(kPacketTag).Value());
     return absl::OkStatus();
   }
 
@@ -240,24 +249,27 @@ REGISTER_CALCULATOR(SleepCalculator);
 class DropCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->Inputs().Tag("PACKET").SetAny();
+    cc->Inputs().Tag(kPacketTag).SetAny();
-    cc->Outputs().Tag("PACKET").SetSameAs(&cc->Inputs().Tag("PACKET"));
+    cc->Outputs().Tag(kPacketTag).SetSameAs(&cc->Inputs().Tag(kPacketTag));
-    cc->InputSidePackets().Tag("DROP_TIMESTAMPS").Set<bool>();
+    cc->InputSidePackets().Tag(kDropTimestampsTag).Set<bool>();
     cc->SetProcessTimestampBounds(true);
     return absl::OkStatus();
   }
 
   absl::Status Process(CalculatorContext* cc) final {
-    if (!cc->Inputs().Tag("PACKET").Value().IsEmpty()) {
+    if (!cc->Inputs().Tag(kPacketTag).Value().IsEmpty()) {
       ++packet_count;
     }
     bool drop = (packet_count == 3);
-    if (!drop && !cc->Inputs().Tag("PACKET").Value().IsEmpty()) {
+    if (!drop && !cc->Inputs().Tag(kPacketTag).Value().IsEmpty()) {
-      cc->Outputs().Tag("PACKET").AddPacket(cc->Inputs().Tag("PACKET").Value());
+      cc->Outputs()
+          .Tag(kPacketTag)
+          .AddPacket(cc->Inputs().Tag(kPacketTag).Value());
     }
-    if (!drop || !cc->InputSidePackets().Tag("DROP_TIMESTAMPS").Get<bool>()) {
+    if (!drop || !cc->InputSidePackets().Tag(kDropTimestampsTag).Get<bool>()) {
-      cc->Outputs().Tag("PACKET").SetNextTimestampBound(
+      cc->Outputs()
-          cc->InputTimestamp().NextAllowedInStream());
+          .Tag(kPacketTag)
+          .SetNextTimestampBound(cc->InputTimestamp().NextAllowedInStream());
     }
     return absl::OkStatus();
   }

mediapipe/calculators/core/gate_calculator.cc

@@ -21,6 +21,11 @@
 namespace mediapipe {
 
 namespace {
+
+constexpr char kStateChangeTag[] = "STATE_CHANGE";
+constexpr char kDisallowTag[] = "DISALLOW";
+constexpr char kAllowTag[] = "ALLOW";
+
 enum GateState {
   GATE_UNINITIALIZED,
   GATE_ALLOW,
@@ -83,30 +88,31 @@ class GateCalculator : public CalculatorBase {
   GateCalculator() {}
 
   static absl::Status CheckAndInitAllowDisallowInputs(CalculatorContract* cc) {
-    bool input_via_side_packet = cc->InputSidePackets().HasTag("ALLOW") ||
+    bool input_via_side_packet = cc->InputSidePackets().HasTag(kAllowTag) ||
-                                 cc->InputSidePackets().HasTag("DISALLOW");
+                                 cc->InputSidePackets().HasTag(kDisallowTag);
     bool input_via_stream =
-        cc->Inputs().HasTag("ALLOW") || cc->Inputs().HasTag("DISALLOW");
+        cc->Inputs().HasTag(kAllowTag) || cc->Inputs().HasTag(kDisallowTag);
     // Only one of input_side_packet or input_stream may specify ALLOW/DISALLOW
     // input.
     RET_CHECK(input_via_side_packet ^ input_via_stream);
 
     if (input_via_side_packet) {
-      RET_CHECK(cc->InputSidePackets().HasTag("ALLOW") ^
+      RET_CHECK(cc->InputSidePackets().HasTag(kAllowTag) ^
-                cc->InputSidePackets().HasTag("DISALLOW"));
+                cc->InputSidePackets().HasTag(kDisallowTag));
 
-      if (cc->InputSidePackets().HasTag("ALLOW")) {
+      if (cc->InputSidePackets().HasTag(kAllowTag)) {
-        cc->InputSidePackets().Tag("ALLOW").Set<bool>();
+        cc->InputSidePackets().Tag(kAllowTag).Set<bool>();
       } else {
-        cc->InputSidePackets().Tag("DISALLOW").Set<bool>();
+        cc->InputSidePackets().Tag(kDisallowTag).Set<bool>();
       }
     } else {
-      RET_CHECK(cc->Inputs().HasTag("ALLOW") ^ cc->Inputs().HasTag("DISALLOW"));
+      RET_CHECK(cc->Inputs().HasTag(kAllowTag) ^
+                cc->Inputs().HasTag(kDisallowTag));
 
-      if (cc->Inputs().HasTag("ALLOW")) {
+      if (cc->Inputs().HasTag(kAllowTag)) {
-        cc->Inputs().Tag("ALLOW").Set<bool>();
+        cc->Inputs().Tag(kAllowTag).Set<bool>();
       } else {
-        cc->Inputs().Tag("DISALLOW").Set<bool>();
+        cc->Inputs().Tag(kDisallowTag).Set<bool>();
       }
     }
     return absl::OkStatus();
@@ -125,8 +131,8 @@ class GateCalculator : public CalculatorBase {
       cc->Outputs().Get("", i).SetSameAs(&cc->Inputs().Get("", i));
     }
 
-    if (cc->Outputs().HasTag("STATE_CHANGE")) {
+    if (cc->Outputs().HasTag(kStateChangeTag)) {
-      cc->Outputs().Tag("STATE_CHANGE").Set<bool>();
+      cc->Outputs().Tag(kStateChangeTag).Set<bool>();
     }
 
     return absl::OkStatus();
@@ -134,14 +140,14 @@ class GateCalculator : public CalculatorBase {
 
   absl::Status Open(CalculatorContext* cc) final {
     use_side_packet_for_allow_disallow_ = false;
-    if (cc->InputSidePackets().HasTag("ALLOW")) {
+    if (cc->InputSidePackets().HasTag(kAllowTag)) {
       use_side_packet_for_allow_disallow_ = true;
       allow_by_side_packet_decision_ =
-          cc->InputSidePackets().Tag("ALLOW").Get<bool>();
+          cc->InputSidePackets().Tag(kAllowTag).Get<bool>();
-    } else if (cc->InputSidePackets().HasTag("DISALLOW")) {
+    } else if (cc->InputSidePackets().HasTag(kDisallowTag)) {
       use_side_packet_for_allow_disallow_ = true;
       allow_by_side_packet_decision_ =
-          !cc->InputSidePackets().Tag("DISALLOW").Get<bool>();
+          !cc->InputSidePackets().Tag(kDisallowTag).Get<bool>();
     }
 
     cc->SetOffset(TimestampDiff(0));
@@ -160,18 +166,18 @@ class GateCalculator : public CalculatorBase {
     if (use_side_packet_for_allow_disallow_) {
       allow = allow_by_side_packet_decision_;
     } else {
-      if (cc->Inputs().HasTag("ALLOW") &&
+      if (cc->Inputs().HasTag(kAllowTag) &&
-          !cc->Inputs().Tag("ALLOW").IsEmpty()) {
+          !cc->Inputs().Tag(kAllowTag).IsEmpty()) {
-        allow = cc->Inputs().Tag("ALLOW").Get<bool>();
+        allow = cc->Inputs().Tag(kAllowTag).Get<bool>();
       }
-      if (cc->Inputs().HasTag("DISALLOW") &&
+      if (cc->Inputs().HasTag(kDisallowTag) &&
-          !cc->Inputs().Tag("DISALLOW").IsEmpty()) {
+          !cc->Inputs().Tag(kDisallowTag).IsEmpty()) {
-        allow = !cc->Inputs().Tag("DISALLOW").Get<bool>();
+        allow = !cc->Inputs().Tag(kDisallowTag).Get<bool>();
       }
     }
     const GateState new_gate_state = allow ? GATE_ALLOW : GATE_DISALLOW;
 
-    if (cc->Outputs().HasTag("STATE_CHANGE")) {
+    if (cc->Outputs().HasTag(kStateChangeTag)) {
       if (last_gate_state_ != GATE_UNINITIALIZED &&
           last_gate_state_ != new_gate_state) {
         VLOG(2) << "State transition in " << cc->NodeName() << " @ "
@@ -179,7 +185,7 @@ class GateCalculator : public CalculatorBase {
                 << ToString(last_gate_state_) << " to "
                 << ToString(new_gate_state);
         cc->Outputs()
-            .Tag("STATE_CHANGE")
+            .Tag(kStateChangeTag)
             .AddPacket(MakePacket<bool>(allow).At(cc->InputTimestamp()));
       }
     }

mediapipe/calculators/core/gate_calculator_test.cc

@@ -22,6 +22,9 @@ namespace mediapipe {
 
 namespace {
 
+constexpr char kDisallowTag[] = "DISALLOW";
+constexpr char kAllowTag[] = "ALLOW";
+
 class GateCalculatorTest : public ::testing::Test {
  protected:
   // Helper to run a graph and return status.
@@ -117,7 +120,7 @@ TEST_F(GateCalculatorTest, AllowByALLOWSidePacketSetToTrue) {
         input_stream: "test_input"
         output_stream: "test_output"
   )");
-  runner()->MutableSidePackets()->Tag("ALLOW") = Adopt(new bool(true));
+  runner()->MutableSidePackets()->Tag(kAllowTag) = Adopt(new bool(true));
 
   constexpr int64 kTimestampValue0 = 42;
   RunTimeStep(kTimestampValue0, true);
@@ -139,7 +142,7 @@ TEST_F(GateCalculatorTest, AllowByDisallowSidePacketSetToFalse) {
         input_stream: "test_input"
         output_stream: "test_output"
   )");
-  runner()->MutableSidePackets()->Tag("DISALLOW") = Adopt(new bool(false));
+  runner()->MutableSidePackets()->Tag(kDisallowTag) = Adopt(new bool(false));
 
   constexpr int64 kTimestampValue0 = 42;
   RunTimeStep(kTimestampValue0, true);
@@ -161,7 +164,7 @@ TEST_F(GateCalculatorTest, DisallowByALLOWSidePacketSetToFalse) {
         input_stream: "test_input"
         output_stream: "test_output"
   )");
-  runner()->MutableSidePackets()->Tag("ALLOW") = Adopt(new bool(false));
+  runner()->MutableSidePackets()->Tag(kAllowTag) = Adopt(new bool(false));
 
   constexpr int64 kTimestampValue0 = 42;
   RunTimeStep(kTimestampValue0, true);
@@ -179,7 +182,7 @@ TEST_F(GateCalculatorTest, DisallowByDISALLOWSidePacketSetToTrue) {
         input_stream: "test_input"
         output_stream: "test_output"
   )");
-  runner()->MutableSidePackets()->Tag("DISALLOW") = Adopt(new bool(true));
+  runner()->MutableSidePackets()->Tag(kDisallowTag) = Adopt(new bool(true));
 
   constexpr int64 kTimestampValue0 = 42;
   RunTimeStep(kTimestampValue0, true);

mediapipe/calculators/core/graph_profile_calculator_test.cc

@@ -39,20 +39,24 @@ using testing::ElementsAre;
 
 namespace mediapipe {
 namespace {
+
+constexpr char kClockTag[] = "CLOCK";
+
 using mediapipe::Clock;
 
 // A Calculator with a fixed Process call latency.
 class SleepCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->InputSidePackets().Tag("CLOCK").Set<std::shared_ptr<Clock>>();
+    cc->InputSidePackets().Tag(kClockTag).Set<std::shared_ptr<Clock>>();
     cc->Inputs().Index(0).SetAny();
     cc->Outputs().Index(0).SetSameAs(&cc->Inputs().Index(0));
     cc->SetTimestampOffset(TimestampDiff(0));
     return absl::OkStatus();
   }
   absl::Status Open(CalculatorContext* cc) final {
-    clock_ = cc->InputSidePackets().Tag("CLOCK").Get<std::shared_ptr<Clock>>();
+    clock_ =
+        cc->InputSidePackets().Tag(kClockTag).Get<std::shared_ptr<Clock>>();
     return absl::OkStatus();
   }
 

mediapipe/calculators/core/matrix_subtract_calculator_test.cc

@@ -29,6 +29,9 @@
 namespace mediapipe {
 namespace {
 
+constexpr char kMinuendTag[] = "MINUEND";
+constexpr char kSubtrahendTag[] = "SUBTRAHEND";
+
 // A 3x4 Matrix of random integers in [0,1000).
 const char kMatrixText[] =
     "rows: 3\n"
@@ -104,12 +107,13 @@ TEST(MatrixSubtractCalculatorTest, SubtractFromInput) {
   CalculatorRunner runner(node_config);
   Matrix* side_matrix = new Matrix();
   MatrixFromTextProto(kMatrixText, side_matrix);
-  runner.MutableSidePackets()->Tag("SUBTRAHEND") = Adopt(side_matrix);
+  runner.MutableSidePackets()->Tag(kSubtrahendTag) = Adopt(side_matrix);
 
   Matrix* input_matrix = new Matrix();
   MatrixFromTextProto(kMatrixText2, input_matrix);
-  runner.MutableInputs()->Tag("MINUEND").packets.push_back(
+  runner.MutableInputs()
-      Adopt(input_matrix).At(Timestamp(0)));
+      ->Tag(kMinuendTag)
+      .packets.push_back(Adopt(input_matrix).At(Timestamp(0)));
 
   MP_ASSERT_OK(runner.Run());
   EXPECT_EQ(1, runner.Outputs().Index(0).packets.size());
@@ -133,12 +137,12 @@ TEST(MatrixSubtractCalculatorTest, SubtractFromSideMatrix) {
   CalculatorRunner runner(node_config);
   Matrix* side_matrix = new Matrix();
   MatrixFromTextProto(kMatrixText, side_matrix);
-  runner.MutableSidePackets()->Tag("MINUEND") = Adopt(side_matrix);
+  runner.MutableSidePackets()->Tag(kMinuendTag) = Adopt(side_matrix);
 
   Matrix* input_matrix = new Matrix();
   MatrixFromTextProto(kMatrixText2, input_matrix);
   runner.MutableInputs()
-      ->Tag("SUBTRAHEND")
+      ->Tag(kSubtrahendTag)
       .packets.push_back(Adopt(input_matrix).At(Timestamp(0)));
 
   MP_ASSERT_OK(runner.Run());

mediapipe/calculators/core/packet_presence_calculator.cc

@@ -17,6 +17,9 @@
 
 namespace mediapipe {
 
+constexpr char kPresenceTag[] = "PRESENCE";
+constexpr char kPacketTag[] = "PACKET";
+
 // For each non empty input packet, emits a single output packet containing a
 // boolean value "true", "false" in response to empty packets (a.k.a. timestamp
 // bound updates) This can be used to "flag" the presence of an arbitrary packet
@@ -58,8 +61,8 @@ namespace mediapipe {
 class PacketPresenceCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->Inputs().Tag("PACKET").SetAny();
+    cc->Inputs().Tag(kPacketTag).SetAny();
-    cc->Outputs().Tag("PRESENCE").Set<bool>();
+    cc->Outputs().Tag(kPresenceTag).Set<bool>();
     // Process() function is invoked in response to input stream timestamp
     // bound updates.
     cc->SetProcessTimestampBounds(true);
@@ -73,8 +76,8 @@ class PacketPresenceCalculator : public CalculatorBase {
 
   absl::Status Process(CalculatorContext* cc) final {
     cc->Outputs()
-        .Tag("PRESENCE")
+        .Tag(kPresenceTag)
-        .AddPacket(MakePacket<bool>(!cc->Inputs().Tag("PACKET").IsEmpty())
+        .AddPacket(MakePacket<bool>(!cc->Inputs().Tag(kPacketTag).IsEmpty())
                        .At(cc->InputTimestamp()));
     return absl::OkStatus();
   }

mediapipe/calculators/core/packet_resampler_calculator.cc

@@ -39,6 +39,11 @@ namespace mediapipe {
 
 REGISTER_CALCULATOR(PacketResamplerCalculator);
 namespace {
+
+constexpr char kSeedTag[] = "SEED";
+constexpr char kVideoHeaderTag[] = "VIDEO_HEADER";
+constexpr char kOptionsTag[] = "OPTIONS";
+
 // Returns a TimestampDiff (assuming microseconds) corresponding to the
 // given time in seconds.
 TimestampDiff TimestampDiffFromSeconds(double seconds) {
@@ -50,16 +55,16 @@ TimestampDiff TimestampDiffFromSeconds(double seconds) {
 absl::Status PacketResamplerCalculator::GetContract(CalculatorContract* cc) {
   const auto& resampler_options =
       cc->Options<PacketResamplerCalculatorOptions>();
-  if (cc->InputSidePackets().HasTag("OPTIONS")) {
+  if (cc->InputSidePackets().HasTag(kOptionsTag)) {
-    cc->InputSidePackets().Tag("OPTIONS").Set<CalculatorOptions>();
+    cc->InputSidePackets().Tag(kOptionsTag).Set<CalculatorOptions>();
   }
   CollectionItemId input_data_id = cc->Inputs().GetId("DATA", 0);
   if (!input_data_id.IsValid()) {
     input_data_id = cc->Inputs().GetId("", 0);
   }
   cc->Inputs().Get(input_data_id).SetAny();
-  if (cc->Inputs().HasTag("VIDEO_HEADER")) {
+  if (cc->Inputs().HasTag(kVideoHeaderTag)) {
-    cc->Inputs().Tag("VIDEO_HEADER").Set<VideoHeader>();
+    cc->Inputs().Tag(kVideoHeaderTag).Set<VideoHeader>();
   }
 
   CollectionItemId output_data_id = cc->Outputs().GetId("DATA", 0);
@@ -67,15 +72,15 @@ absl::Status PacketResamplerCalculator::GetContract(CalculatorContract* cc) {
     output_data_id = cc->Outputs().GetId("", 0);
   }
   cc->Outputs().Get(output_data_id).SetSameAs(&cc->Inputs().Get(input_data_id));
-  if (cc->Outputs().HasTag("VIDEO_HEADER")) {
+  if (cc->Outputs().HasTag(kVideoHeaderTag)) {
-    cc->Outputs().Tag("VIDEO_HEADER").Set<VideoHeader>();
+    cc->Outputs().Tag(kVideoHeaderTag).Set<VideoHeader>();
   }
 
   if (resampler_options.jitter() != 0.0) {
     RET_CHECK_GT(resampler_options.jitter(), 0.0);
     RET_CHECK_LE(resampler_options.jitter(), 1.0);
-    RET_CHECK(cc->InputSidePackets().HasTag("SEED"));
+    RET_CHECK(cc->InputSidePackets().HasTag(kSeedTag));
-    cc->InputSidePackets().Tag("SEED").Set<std::string>();
+    cc->InputSidePackets().Tag(kSeedTag).Set<std::string>();
   }
   return absl::OkStatus();
 }
@@ -143,9 +148,9 @@ absl::Status PacketResamplerCalculator::Open(CalculatorContext* cc) {
 
 absl::Status PacketResamplerCalculator::Process(CalculatorContext* cc) {
   if (cc->InputTimestamp() == Timestamp::PreStream() &&
-      cc->Inputs().UsesTags() && cc->Inputs().HasTag("VIDEO_HEADER") &&
+      cc->Inputs().UsesTags() && cc->Inputs().HasTag(kVideoHeaderTag) &&
-      !cc->Inputs().Tag("VIDEO_HEADER").IsEmpty()) {
+      !cc->Inputs().Tag(kVideoHeaderTag).IsEmpty()) {
-    video_header_ = cc->Inputs().Tag("VIDEO_HEADER").Get<VideoHeader>();
+    video_header_ = cc->Inputs().Tag(kVideoHeaderTag).Get<VideoHeader>();
     video_header_.frame_rate = frame_rate_;
     if (cc->Inputs().Get(input_data_id_).IsEmpty()) {
       return absl::OkStatus();
@@ -234,7 +239,7 @@ absl::Status LegacyJitterWithReflectionStrategy::Open(CalculatorContext* cc) {
                     "ignored, because we are adding jitter.";
   }
 
-  const auto& seed = cc->InputSidePackets().Tag("SEED").Get<std::string>();
+  const auto& seed = cc->InputSidePackets().Tag(kSeedTag).Get<std::string>();
   random_ = CreateSecureRandom(seed);
   if (random_ == nullptr) {
     return absl::InvalidArgumentError(
@@ -357,7 +362,7 @@ absl::Status ReproducibleJitterWithReflectionStrategy::Open(
                     "ignored, because we are adding jitter.";
   }
 
-  const auto& seed = cc->InputSidePackets().Tag("SEED").Get<std::string>();
+  const auto& seed = cc->InputSidePackets().Tag(kSeedTag).Get<std::string>();
   random_ = CreateSecureRandom(seed);
   if (random_ == nullptr) {
     return absl::InvalidArgumentError(
@@ -504,7 +509,7 @@ absl::Status JitterWithoutReflectionStrategy::Open(CalculatorContext* cc) {
                     "ignored, because we are adding jitter.";
   }
 
-  const auto& seed = cc->InputSidePackets().Tag("SEED").Get<std::string>();
+  const auto& seed = cc->InputSidePackets().Tag(kSeedTag).Get<std::string>();
   random_ = CreateSecureRandom(seed);
   if (random_ == nullptr) {
     return absl::InvalidArgumentError(
@@ -635,9 +640,9 @@ absl::Status NoJitterStrategy::Process(CalculatorContext* cc) {
           base_timestamp_ +
           TimestampDiffFromSeconds(first_index / calculator_->frame_rate_);
     }
-    if (cc->Outputs().UsesTags() && cc->Outputs().HasTag("VIDEO_HEADER")) {
+    if (cc->Outputs().UsesTags() && cc->Outputs().HasTag(kVideoHeaderTag)) {
       cc->Outputs()
-          .Tag("VIDEO_HEADER")
+          .Tag(kVideoHeaderTag)
           .Add(new VideoHeader(calculator_->video_header_),
                Timestamp::PreStream());
     }

mediapipe/calculators/core/packet_resampler_calculator_test.cc

@@ -32,6 +32,12 @@ namespace mediapipe {
 
 using ::testing::ElementsAre;
 namespace {
+
+constexpr char kOptionsTag[] = "OPTIONS";
+constexpr char kSeedTag[] = "SEED";
+constexpr char kVideoHeaderTag[] = "VIDEO_HEADER";
+constexpr char kDataTag[] = "DATA";
+
 // A simple version of CalculatorRunner with built-in convenience
 // methods for setting inputs from a vector and checking outputs
 // against expected outputs (both timestamps and contents).
@@ -464,7 +470,7 @@ TEST(PacketResamplerCalculatorTest, SetVideoHeader) {
   )pb"));
 
   for (const int64 ts : {0, 5000, 10010, 15001, 19990}) {
-    runner.MutableInputs()->Tag("DATA").packets.push_back(
+    runner.MutableInputs()->Tag(kDataTag).packets.push_back(
         Adopt(new std::string(absl::StrCat("Frame #", ts))).At(Timestamp(ts)));
   }
   VideoHeader video_header_in;
@@ -474,16 +480,16 @@ TEST(PacketResamplerCalculatorTest, SetVideoHeader) {
   video_header_in.duration = 1.0;
   video_header_in.format = ImageFormat::SRGB;
   runner.MutableInputs()
-      ->Tag("VIDEO_HEADER")
+      ->Tag(kVideoHeaderTag)
       .packets.push_back(
           Adopt(new VideoHeader(video_header_in)).At(Timestamp::PreStream()));
   MP_ASSERT_OK(runner.Run());
 
-  ASSERT_EQ(1, runner.Outputs().Tag("VIDEO_HEADER").packets.size());
+  ASSERT_EQ(1, runner.Outputs().Tag(kVideoHeaderTag).packets.size());
   EXPECT_EQ(Timestamp::PreStream(),
-            runner.Outputs().Tag("VIDEO_HEADER").packets[0].Timestamp());
+            runner.Outputs().Tag(kVideoHeaderTag).packets[0].Timestamp());
   const VideoHeader& video_header_out =
-      runner.Outputs().Tag("VIDEO_HEADER").packets[0].Get<VideoHeader>();
+      runner.Outputs().Tag(kVideoHeaderTag).packets[0].Get<VideoHeader>();
   EXPECT_EQ(video_header_in.width, video_header_out.width);
   EXPECT_EQ(video_header_in.height, video_header_out.height);
   EXPECT_DOUBLE_EQ(50.0, video_header_out.frame_rate);
@@ -725,7 +731,7 @@ TEST(PacketResamplerCalculatorTest, OptionsSidePacket) {
               [mediapipe.PacketResamplerCalculatorOptions.ext] {
                 frame_rate: 30
               })pb"));
-    runner.MutableSidePackets()->Tag("OPTIONS") = Adopt(options);
+    runner.MutableSidePackets()->Tag(kOptionsTag) = Adopt(options);
     runner.SetInput({-222, 15000, 32000, 49999, 150000});
     MP_ASSERT_OK(runner.Run());
     EXPECT_EQ(6, runner.Outputs().Index(0).packets.size());
@@ -740,7 +746,7 @@ TEST(PacketResamplerCalculatorTest, OptionsSidePacket) {
             frame_rate: 30
             base_timestamp: 0
           })pb"));
-    runner.MutableSidePackets()->Tag("OPTIONS") = Adopt(options);
+    runner.MutableSidePackets()->Tag(kOptionsTag) = Adopt(options);
 
     runner.SetInput({-222, 15000, 32000, 49999, 150000});
     MP_ASSERT_OK(runner.Run());

mediapipe/calculators/core/packet_thinner_calculator_test.cc

@@ -29,6 +29,8 @@
 namespace mediapipe {
 namespace {
 
+constexpr char kPeriodTag[] = "PERIOD";
+
 // A simple version of CalculatorRunner with built-in convenience methods for
 // setting inputs from a vector and checking outputs against a vector of
 // expected outputs.
@@ -121,7 +123,7 @@ TEST(PacketThinnerCalculatorTest, ASyncUniformStreamThinningTestBySidePacket) {
 
   SimpleRunner runner(node);
   runner.SetInput({2, 4, 6, 8, 10, 12, 14});
-  runner.MutableSidePackets()->Tag("PERIOD") = MakePacket<int64>(5);
+  runner.MutableSidePackets()->Tag(kPeriodTag) = MakePacket<int64>(5);
   MP_ASSERT_OK(runner.Run());
 
   const std::vector<int64> expected_timestamps = {2, 8, 14};
@@ -160,7 +162,7 @@ TEST(PacketThinnerCalculatorTest, SyncUniformStreamThinningTestBySidePacket1) {
 
   SimpleRunner runner(node);
   runner.SetInput({2, 4, 6, 8, 10, 12, 14});
-  runner.MutableSidePackets()->Tag("PERIOD") = MakePacket<int64>(5);
+  runner.MutableSidePackets()->Tag(kPeriodTag) = MakePacket<int64>(5);
   MP_ASSERT_OK(runner.Run());
 
   const std::vector<int64> expected_timestamps = {2, 6, 10, 14};

mediapipe/calculators/core/previous_loopback_calculator_test.cc

@@ -39,6 +39,8 @@ using ::testing::Pair;
 using ::testing::Value;
 namespace {
 
+constexpr char kDisallowTag[] = "DISALLOW";
+
 // Returns the timestamp values for a vector of Packets.
 // TODO: puth this kind of test util in a common place.
 std::vector<int64> TimestampValues(const std::vector<Packet>& packets) {
@@ -702,14 +704,14 @@ class DroppingGateCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
     cc->Inputs().Index(0).SetAny();
-    cc->Inputs().Tag("DISALLOW").Set<bool>();
+    cc->Inputs().Tag(kDisallowTag).Set<bool>();
     cc->Outputs().Index(0).SetSameAs(&cc->Inputs().Index(0));
     return absl::OkStatus();
   }
 
   absl::Status Process(CalculatorContext* cc) final {
     if (!cc->Inputs().Index(0).IsEmpty() &&
-        !cc->Inputs().Tag("DISALLOW").Get<bool>()) {
+        !cc->Inputs().Tag(kDisallowTag).Get<bool>()) {
       cc->Outputs().Index(0).AddPacket(cc->Inputs().Index(0).Value());
     }
     return absl::OkStatus();

mediapipe/calculators/core/quantize_float_vector_calculator.cc

@@ -41,11 +41,14 @@
 //   }
 namespace mediapipe {
 
+constexpr char kEncodedTag[] = "ENCODED";
+constexpr char kFloatVectorTag[] = "FLOAT_VECTOR";
+
 class QuantizeFloatVectorCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->Inputs().Tag("FLOAT_VECTOR").Set<std::vector<float>>();
+    cc->Inputs().Tag(kFloatVectorTag).Set<std::vector<float>>();
-    cc->Outputs().Tag("ENCODED").Set<std::string>();
+    cc->Outputs().Tag(kEncodedTag).Set<std::string>();
     return absl::OkStatus();
   }
 
@@ -70,7 +73,7 @@ class QuantizeFloatVectorCalculator : public CalculatorBase {
 
   absl::Status Process(CalculatorContext* cc) final {
     const std::vector<float>& float_vector =
-        cc->Inputs().Tag("FLOAT_VECTOR").Value().Get<std::vector<float>>();
+        cc->Inputs().Tag(kFloatVectorTag).Value().Get<std::vector<float>>();
     int feature_size = float_vector.size();
     std::string encoded_features;
     encoded_features.reserve(feature_size);
@@ -86,7 +89,9 @@ class QuantizeFloatVectorCalculator : public CalculatorBase {
           (old_value - min_quantized_value_) * (255.0 / range_));
       encoded_features += encoded;
     }
-    cc->Outputs().Tag("ENCODED").AddPacket(
+    cc->Outputs()
+        .Tag(kEncodedTag)
+        .AddPacket(
             MakePacket<std::string>(encoded_features).At(cc->InputTimestamp()));
     return absl::OkStatus();
   }

mediapipe/calculators/core/quantize_float_vector_calculator_test.cc

@@ -25,6 +25,9 @@
 
 namespace mediapipe {
 
+constexpr char kEncodedTag[] = "ENCODED";
+constexpr char kFloatVectorTag[] = "FLOAT_VECTOR";
+
 TEST(QuantizeFloatVectorCalculatorTest, WrongConfig) {
   CalculatorGraphConfig::Node node_config =
       ParseTextProtoOrDie<CalculatorGraphConfig::Node>(R"pb(
@@ -40,7 +43,7 @@ TEST(QuantizeFloatVectorCalculatorTest, WrongConfig) {
   CalculatorRunner runner(node_config);
   std::vector<float> empty_vector;
   runner.MutableInputs()
-      ->Tag("FLOAT_VECTOR")
+      ->Tag(kFloatVectorTag)
       .packets.push_back(
           MakePacket<std::vector<float>>(empty_vector).At(Timestamp(0)));
   auto status = runner.Run();
@@ -67,7 +70,7 @@ TEST(QuantizeFloatVectorCalculatorTest, WrongConfig2) {
   CalculatorRunner runner(node_config);
   std::vector<float> empty_vector;
   runner.MutableInputs()
-      ->Tag("FLOAT_VECTOR")
+      ->Tag(kFloatVectorTag)
       .packets.push_back(
           MakePacket<std::vector<float>>(empty_vector).At(Timestamp(0)));
   auto status = runner.Run();
@@ -94,7 +97,7 @@ TEST(QuantizeFloatVectorCalculatorTest, WrongConfig3) {
   CalculatorRunner runner(node_config);
   std::vector<float> empty_vector;
   runner.MutableInputs()
-      ->Tag("FLOAT_VECTOR")
+      ->Tag(kFloatVectorTag)
       .packets.push_back(
           MakePacket<std::vector<float>>(empty_vector).At(Timestamp(0)));
   auto status = runner.Run();
@@ -121,11 +124,12 @@ TEST(QuantizeFloatVectorCalculatorTest, TestEmptyVector) {
   CalculatorRunner runner(node_config);
   std::vector<float> empty_vector;
   runner.MutableInputs()
-      ->Tag("FLOAT_VECTOR")
+      ->Tag(kFloatVectorTag)
       .packets.push_back(
           MakePacket<std::vector<float>>(empty_vector).At(Timestamp(0)));
   MP_ASSERT_OK(runner.Run());
-  const std::vector<Packet>& outputs = runner.Outputs().Tag("ENCODED").packets;
+  const std::vector<Packet>& outputs =
+      runner.Outputs().Tag(kEncodedTag).packets;
   EXPECT_EQ(1, outputs.size());
   EXPECT_TRUE(outputs[0].Get<std::string>().empty());
   EXPECT_EQ(Timestamp(0), outputs[0].Timestamp());
@@ -147,11 +151,12 @@ TEST(QuantizeFloatVectorCalculatorTest, TestNonEmptyVector) {
   CalculatorRunner runner(node_config);
   std::vector<float> vector = {0.0f, -64.0f, 64.0f, -32.0f, 32.0f};
   runner.MutableInputs()
-      ->Tag("FLOAT_VECTOR")
+      ->Tag(kFloatVectorTag)
       .packets.push_back(
           MakePacket<std::vector<float>>(vector).At(Timestamp(0)));
   MP_ASSERT_OK(runner.Run());
-  const std::vector<Packet>& outputs = runner.Outputs().Tag("ENCODED").packets;
+  const std::vector<Packet>& outputs =
+      runner.Outputs().Tag(kEncodedTag).packets;
   EXPECT_EQ(1, outputs.size());
   const std::string& result = outputs[0].Get<std::string>();
   ASSERT_FALSE(result.empty());
@@ -185,11 +190,12 @@ TEST(QuantizeFloatVectorCalculatorTest, TestSaturation) {
   CalculatorRunner runner(node_config);
   std::vector<float> vector = {-65.0f, 65.0f};
   runner.MutableInputs()
-      ->Tag("FLOAT_VECTOR")
+      ->Tag(kFloatVectorTag)
       .packets.push_back(
           MakePacket<std::vector<float>>(vector).At(Timestamp(0)));
   MP_ASSERT_OK(runner.Run());
-  const std::vector<Packet>& outputs = runner.Outputs().Tag("ENCODED").packets;
+  const std::vector<Packet>& outputs =
+      runner.Outputs().Tag(kEncodedTag).packets;
   EXPECT_EQ(1, outputs.size());
   const std::string& result = outputs[0].Get<std::string>();
   ASSERT_FALSE(result.empty());

mediapipe/calculators/core/real_time_flow_limiter_calculator.cc

@@ -23,6 +23,9 @@
 
 namespace mediapipe {
 
+constexpr char kAllowTag[] = "ALLOW";
+constexpr char kMaxInFlightTag[] = "MAX_IN_FLIGHT";
+
 // RealTimeFlowLimiterCalculator is used to limit the number of pipelined
 // processing operations in a section of the graph.
 //
@@ -86,11 +89,11 @@ class RealTimeFlowLimiterCalculator : public CalculatorBase {
       cc->Outputs().Get("", i).SetSameAs(&(cc->Inputs().Get("", i)));
     }
     cc->Inputs().Get("FINISHED", 0).SetAny();
-    if (cc->InputSidePackets().HasTag("MAX_IN_FLIGHT")) {
+    if (cc->InputSidePackets().HasTag(kMaxInFlightTag)) {
-      cc->InputSidePackets().Tag("MAX_IN_FLIGHT").Set<int>();
+      cc->InputSidePackets().Tag(kMaxInFlightTag).Set<int>();
     }
-    if (cc->Outputs().HasTag("ALLOW")) {
+    if (cc->Outputs().HasTag(kAllowTag)) {
-      cc->Outputs().Tag("ALLOW").Set<bool>();
+      cc->Outputs().Tag(kAllowTag).Set<bool>();
     }
 
     cc->SetInputStreamHandler("ImmediateInputStreamHandler");
@@ -101,8 +104,8 @@ class RealTimeFlowLimiterCalculator : public CalculatorBase {
   absl::Status Open(CalculatorContext* cc) final {
     finished_id_ = cc->Inputs().GetId("FINISHED", 0);
     max_in_flight_ = 1;
-    if (cc->InputSidePackets().HasTag("MAX_IN_FLIGHT")) {
+    if (cc->InputSidePackets().HasTag(kMaxInFlightTag)) {
-      max_in_flight_ = cc->InputSidePackets().Tag("MAX_IN_FLIGHT").Get<int>();
+      max_in_flight_ = cc->InputSidePackets().Tag(kMaxInFlightTag).Get<int>();
     }
     RET_CHECK_GE(max_in_flight_, 1);
     num_in_flight_ = 0;

mediapipe/calculators/core/real_time_flow_limiter_calculator_test.cc

@@ -33,6 +33,9 @@
 namespace mediapipe {
 
 namespace {
+
+constexpr char kFinishedTag[] = "FINISHED";
+
 // A simple Semaphore for synchronizing test threads.
 class AtomicSemaphore {
  public:
@@ -112,7 +115,7 @@ TEST(RealTimeFlowLimiterCalculator, BasicTest) {
     Timestamp timestamp =
         Timestamp((i + 1) * Timestamp::kTimestampUnitsPerSecond);
     runner.MutableInputs()
-        ->Tag("FINISHED")
+        ->Tag(kFinishedTag)
         .packets.push_back(MakePacket<bool>(true).At(timestamp));
   }
 

mediapipe/calculators/core/sequence_shift_calculator_test.cc

@@ -22,6 +22,8 @@ namespace mediapipe {
 
 namespace {
 
+constexpr char kPacketOffsetTag[] = "PACKET_OFFSET";
+
 // Adds packets containing integers equal to their original timestamp.
 void AddPackets(CalculatorRunner* runner) {
   for (int i = 0; i < 10; ++i) {
@@ -111,7 +113,7 @@ TEST(SequenceShiftCalculatorTest, SidePacketOffset) {
 
   CalculatorRunner runner(node);
   AddPackets(&runner);
-  runner.MutableSidePackets()->Tag("PACKET_OFFSET") = Adopt(new int(-2));
+  runner.MutableSidePackets()->Tag(kPacketOffsetTag) = Adopt(new int(-2));
   MP_ASSERT_OK(runner.Run());
   const std::vector<Packet>& input_packets =
       runner.MutableInputs()->Index(0).packets;

mediapipe/calculators/image/image_transformation_calculator.cc

@@ -102,6 +102,10 @@ mediapipe::ScaleMode_Mode ParseScaleMode(
 //   IMAGE: ImageFrame representing the input image.
 //   IMAGE_GPU: GpuBuffer representing the input image.
 //
+//   OUTPUT_DIMENSIONS (optional): The output width and height in pixels as
+//   pair<int, int>. If set, it will override corresponding field in calculator
+//   options and input side packet.
+//
 //   ROTATION_DEGREES (optional): The counterclockwise rotation angle in
 //   degrees. This allows different rotation angles for different frames. It has
 //   to be a multiple of 90 degrees. If provided, it overrides the
@@ -221,6 +225,10 @@ absl::Status ImageTransformationCalculator::GetContract(
   }
 #endif  // !MEDIAPIPE_DISABLE_GPU
 
+  if (cc->Inputs().HasTag("OUTPUT_DIMENSIONS")) {
+    cc->Inputs().Tag("OUTPUT_DIMENSIONS").Set<std::pair<int, int>>();
+  }
+
   if (cc->Inputs().HasTag("ROTATION_DEGREES")) {
     cc->Inputs().Tag("ROTATION_DEGREES").Set<int>();
   }
@@ -329,6 +337,13 @@ absl::Status ImageTransformationCalculator::Process(CalculatorContext* cc) {
       !cc->Inputs().Tag("FLIP_VERTICALLY").IsEmpty()) {
     flip_vertically_ = cc->Inputs().Tag("FLIP_VERTICALLY").Get<bool>();
   }
+  if (cc->Inputs().HasTag("OUTPUT_DIMENSIONS") &&
+      !cc->Inputs().Tag("OUTPUT_DIMENSIONS").IsEmpty()) {
+    const auto& image_size =
+        cc->Inputs().Tag("OUTPUT_DIMENSIONS").Get<std::pair<int, int>>();
+    output_width_ = image_size.first;
+    output_height_ = image_size.second;
+  }
 
   if (use_gpu_) {
 #if !MEDIAPIPE_DISABLE_GPU

mediapipe/calculators/tensorflow/BUILD

@@ -88,6 +88,13 @@ proto_library(
     deps = ["//mediapipe/framework:calculator_proto"],
 )
 
+proto_library(
+    name = "tensor_to_vector_string_calculator_options_proto",
+    srcs = ["tensor_to_vector_string_calculator_options.proto"],
+    visibility = ["//visibility:public"],
+    deps = ["//mediapipe/framework:calculator_proto"],
+)
+
 proto_library(
     name = "unpack_media_sequence_calculator_proto",
     srcs = ["unpack_media_sequence_calculator.proto"],
@@ -257,6 +264,14 @@ mediapipe_cc_proto_library(
     deps = [":tensor_to_vector_float_calculator_options_proto"],
 )
 
+mediapipe_cc_proto_library(
+    name = "tensor_to_vector_string_calculator_options_cc_proto",
+    srcs = ["tensor_to_vector_string_calculator_options.proto"],
+    cc_deps = ["//mediapipe/framework:calculator_cc_proto"],
+    visibility = ["//visibility:public"],
+    deps = [":tensor_to_vector_string_calculator_options_proto"],
+)
+
 mediapipe_cc_proto_library(
     name = "unpack_media_sequence_calculator_cc_proto",
     srcs = ["unpack_media_sequence_calculator.proto"],
@@ -694,6 +709,26 @@ cc_library(
     alwayslink = 1,
 )
 
+cc_library(
+    name = "tensor_to_vector_string_calculator",
+    srcs = ["tensor_to_vector_string_calculator.cc"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework/port:status",
+        "//mediapipe/framework/port:ret_check",
+        ":tensor_to_vector_string_calculator_options_cc_proto",
+    ] + select({
+        "//conditions:default": [
+            "@org_tensorflow//tensorflow/core:framework",
+        ],
+        "//mediapipe:android": [
+            "@org_tensorflow//tensorflow/core:portable_tensorflow_lib_lite",
+        ],
+    }),
+    alwayslink = 1,
+)
+
 cc_library(
     name = "unpack_media_sequence_calculator",
     srcs = ["unpack_media_sequence_calculator.cc"],
@@ -1059,6 +1094,20 @@ cc_test(
     ],
 )
 
+cc_test(
+    name = "tensor_to_vector_string_calculator_test",
+    srcs = ["tensor_to_vector_string_calculator_test.cc"],
+    deps = [
+        ":tensor_to_vector_string_calculator",
+        ":tensor_to_vector_string_calculator_options_cc_proto",
+        "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework:calculator_runner",
+        "//mediapipe/framework/port:gtest_main",
+        "@org_tensorflow//tensorflow/core:framework",
+        "@org_tensorflow//tensorflow/core:protos_all_cc",
+    ],
+)
+
 cc_test(
     name = "unpack_media_sequence_calculator_test",
     srcs = ["unpack_media_sequence_calculator_test.cc"],

mediapipe/calculators/tensorflow/pack_media_sequence_calculator_test.cc

@@ -40,6 +40,24 @@ namespace {
 namespace tf = ::tensorflow;
 namespace mpms = mediapipe::mediasequence;
 
+constexpr char kBboxTag[] = "BBOX";
+constexpr char kEncodedMediaStartTimestampTag[] =
+    "ENCODED_MEDIA_START_TIMESTAMP";
+constexpr char kEncodedMediaTag[] = "ENCODED_MEDIA";
+constexpr char kClassSegmentationTag[] = "CLASS_SEGMENTATION";
+constexpr char kKeypointsTestTag[] = "KEYPOINTS_TEST";
+constexpr char kBboxPredictedTag[] = "BBOX_PREDICTED";
+constexpr char kAudioOtherTag[] = "AUDIO_OTHER";
+constexpr char kAudioTestTag[] = "AUDIO_TEST";
+constexpr char kForwardFlowEncodedTag[] = "FORWARD_FLOW_ENCODED";
+constexpr char kFloatContextFeatureOtherTag[] = "FLOAT_CONTEXT_FEATURE_OTHER";
+constexpr char kFloatContextFeatureTestTag[] = "FLOAT_CONTEXT_FEATURE_TEST";
+constexpr char kFloatFeatureOtherTag[] = "FLOAT_FEATURE_OTHER";
+constexpr char kFloatFeatureTestTag[] = "FLOAT_FEATURE_TEST";
+constexpr char kImagePrefixTag[] = "IMAGE_PREFIX";
+constexpr char kSequenceExampleTag[] = "SEQUENCE_EXAMPLE";
+constexpr char kImageTag[] = "IMAGE";
+
 class PackMediaSequenceCalculatorTest : public ::testing::Test {
  protected:
   void SetUpCalculator(const std::vector<std::string>& input_streams,
@@ -83,17 +101,17 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksTwoImages) {
   for (int i = 0; i < num_images; ++i) {
     auto image_ptr =
         ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_image);
-    runner_->MutableInputs()->Tag("IMAGE").packets.push_back(
+    runner_->MutableInputs()->Tag(kImageTag).packets.push_back(
         Adopt(image_ptr.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -127,17 +145,17 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksTwoPrefixedImages) {
     auto image_ptr =
         ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_image);
     runner_->MutableInputs()
-        ->Tag("IMAGE_PREFIX")
+        ->Tag(kImagePrefixTag)
         .packets.push_back(Adopt(image_ptr.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -161,21 +179,21 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksTwoFloatLists) {
   for (int i = 0; i < num_timesteps; ++i) {
     auto vf_ptr = ::absl::make_unique<std::vector<float>>(2, 2 << i);
     runner_->MutableInputs()
-        ->Tag("FLOAT_FEATURE_TEST")
+        ->Tag(kFloatFeatureTestTag)
         .packets.push_back(Adopt(vf_ptr.release()).At(Timestamp(i)));
     vf_ptr = ::absl::make_unique<std::vector<float>>(2, 2 << i);
     runner_->MutableInputs()
-        ->Tag("FLOAT_FEATURE_OTHER")
+        ->Tag(kFloatFeatureOtherTag)
         .packets.push_back(Adopt(vf_ptr.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -228,20 +246,20 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksTwoContextFloatLists) {
 
   auto vf_ptr = absl::make_unique<std::vector<float>>(2, 3);
   runner_->MutableInputs()
-      ->Tag("FLOAT_CONTEXT_FEATURE_TEST")
+      ->Tag(kFloatContextFeatureTestTag)
       .packets.push_back(Adopt(vf_ptr.release()).At(Timestamp::PostStream()));
   vf_ptr = absl::make_unique<std::vector<float>>(2, 4);
   runner_->MutableInputs()
-      ->Tag("FLOAT_CONTEXT_FEATURE_OTHER")
+      ->Tag(kFloatContextFeatureOtherTag)
       .packets.push_back(Adopt(vf_ptr.release()).At(Timestamp::PostStream()));
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -259,7 +277,7 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksAdditionalContext) {
   SetUpCalculator({"IMAGE:images"}, context, false, true);
 
   auto input_sequence = ::absl::make_unique<tf::SequenceExample>();
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
   cv::Mat image(2, 3, CV_8UC3, cv::Scalar(0, 0, 255));
   std::vector<uchar> bytes;
@@ -268,13 +286,13 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksAdditionalContext) {
   encoded_image.set_encoded_image(bytes.data(), bytes.size());
   auto image_ptr =
       ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_image);
-  runner_->MutableInputs()->Tag("IMAGE").packets.push_back(
+  runner_->MutableInputs()->Tag(kImageTag).packets.push_back(
       Adopt(image_ptr.release()).At(Timestamp(0)));
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -307,17 +325,17 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksTwoForwardFlowEncodeds) {
     auto flow_ptr =
         ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_flow);
     runner_->MutableInputs()
-        ->Tag("FORWARD_FLOW_ENCODED")
+        ->Tag(kForwardFlowEncodedTag)
         .packets.push_back(Adopt(flow_ptr.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -371,17 +389,17 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksTwoBBoxDetections) {
     detections->push_back(detection);
 
     runner_->MutableInputs()
-        ->Tag("BBOX_PREDICTED")
+        ->Tag(kBboxPredictedTag)
         .packets.push_back(Adopt(detections.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -450,11 +468,11 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksBBoxWithoutImageDims) {
     detections->push_back(detection);
 
     runner_->MutableInputs()
-        ->Tag("BBOX_PREDICTED")
+        ->Tag(kBboxPredictedTag)
         .packets.push_back(Adopt(detections.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   auto status = runner_->Run();
@@ -498,7 +516,7 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksBBoxWithImages) {
     detections->push_back(detection);
 
     runner_->MutableInputs()
-        ->Tag("BBOX_PREDICTED")
+        ->Tag(kBboxPredictedTag)
         .packets.push_back(Adopt(detections.release()).At(Timestamp(i)));
   }
   cv::Mat image(height, width, CV_8UC3, cv::Scalar(0, 0, 255));
@@ -513,16 +531,16 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksBBoxWithImages) {
   for (int i = 0; i < num_images; ++i) {
     auto image_ptr =
         ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_image);
-    runner_->MutableInputs()->Tag("IMAGE").packets.push_back(
+    runner_->MutableInputs()->Tag(kImageTag).packets.push_back(
         Adopt(image_ptr.release()).At(Timestamp(i)));
   }
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -564,18 +582,18 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksTwoKeypoints) {
   absl::flat_hash_map<std::string, std::vector<std::pair<float, float>>>
       points = {{"HEAD", {{0.1, 0.2}, {0.3, 0.4}}}, {"TAIL", {{0.5, 0.6}}}};
   runner_->MutableInputs()
-      ->Tag("KEYPOINTS_TEST")
+      ->Tag(kKeypointsTestTag)
       .packets.push_back(PointToForeign(&points).At(Timestamp(0)));
   runner_->MutableInputs()
-      ->Tag("KEYPOINTS_TEST")
+      ->Tag(kKeypointsTestTag)
       .packets.push_back(PointToForeign(&points).At(Timestamp(1)));
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -615,17 +633,17 @@ TEST_F(PackMediaSequenceCalculatorTest, PacksTwoMaskDetections) {
     detections->push_back(detection);
 
     runner_->MutableInputs()
-        ->Tag("CLASS_SEGMENTATION")
+        ->Tag(kClassSegmentationTag)
         .packets.push_back(Adopt(detections.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -664,17 +682,17 @@ TEST_F(PackMediaSequenceCalculatorTest, MissingStreamOK) {
     auto flow_ptr =
         ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_flow);
     runner_->MutableInputs()
-        ->Tag("FORWARD_FLOW_ENCODED")
+        ->Tag(kForwardFlowEncodedTag)
         .packets.push_back(Adopt(flow_ptr.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -710,11 +728,11 @@ TEST_F(PackMediaSequenceCalculatorTest, MissingStreamNotOK) {
     auto flow_ptr =
         ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_flow);
     runner_->MutableInputs()
-        ->Tag("FORWARD_FLOW_ENCODED")
+        ->Tag(kForwardFlowEncodedTag)
         .packets.push_back(Adopt(flow_ptr.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   absl::Status status = runner_->Run();
@@ -731,13 +749,13 @@ TEST_F(PackMediaSequenceCalculatorTest, TestReplacingImages) {
   mpms::AddImageTimestamp(1, input_sequence.get());
   mpms::AddImageTimestamp(2, input_sequence.get());
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -757,13 +775,13 @@ TEST_F(PackMediaSequenceCalculatorTest, TestReplacingFlowImages) {
   mpms::AddForwardFlowTimestamp(1, input_sequence.get());
   mpms::AddForwardFlowTimestamp(2, input_sequence.get());
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -794,13 +812,13 @@ TEST_F(PackMediaSequenceCalculatorTest, TestReplacingFloatVectors) {
             mpms::GetFeatureTimestampSize("OTHER", *input_sequence));
   ASSERT_EQ(num_timesteps,
             mpms::GetFeatureFloatsSize("OTHER", *input_sequence));
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -826,7 +844,7 @@ TEST_F(PackMediaSequenceCalculatorTest, TestReconcilingAnnotations) {
   for (int i = 0; i < num_images; ++i) {
     auto image_ptr =
         ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_image);
-    runner_->MutableInputs()->Tag("IMAGE").packets.push_back(
+    runner_->MutableInputs()->Tag(kImageTag).packets.push_back(
         Adopt(image_ptr.release()).At(Timestamp((i + 1) * 10)));
   }
 
@@ -838,11 +856,11 @@ TEST_F(PackMediaSequenceCalculatorTest, TestReconcilingAnnotations) {
   mpms::AddBBoxTimestamp("PREFIX", 9, input_sequence.get());
   mpms::AddBBoxTimestamp("PREFIX", 22, input_sequence.get());
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
   MP_ASSERT_OK(runner_->Run());
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("SEQUENCE_EXAMPLE").packets;
+      runner_->Outputs().Tag(kSequenceExampleTag).packets;
   ASSERT_EQ(1, output_packets.size());
   const tf::SequenceExample& output_sequence =
       output_packets[0].Get<tf::SequenceExample>();
@@ -879,7 +897,7 @@ TEST_F(PackMediaSequenceCalculatorTest, TestOverwritingAndReconciling) {
   for (int i = 0; i < num_images; ++i) {
     auto image_ptr =
         ::absl::make_unique<OpenCvImageEncoderCalculatorResults>(encoded_image);
-    runner_->MutableInputs()->Tag("IMAGE").packets.push_back(
+    runner_->MutableInputs()->Tag(kImageTag).packets.push_back(
         Adopt(image_ptr.release()).At(Timestamp(i)));
   }
 
@@ -893,7 +911,7 @@ TEST_F(PackMediaSequenceCalculatorTest, TestOverwritingAndReconciling) {
     Location::CreateRelativeBBoxLocation(0, 0.5, 0.5, 0.5)
         .ConvertToProto(detection.mutable_location_data());
     detections->push_back(detection);
-    runner_->MutableInputs()->Tag("BBOX").packets.push_back(
+    runner_->MutableInputs()->Tag(kBboxTag).packets.push_back(
         Adopt(detections.release()).At(Timestamp(i)));
   }
 
@@ -909,7 +927,7 @@ TEST_F(PackMediaSequenceCalculatorTest, TestOverwritingAndReconciling) {
     mpms::AddBBoxTrackIndex({-1}, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
   // If the all the previous values aren't cleared, this assert will fail.
   MP_ASSERT_OK(runner_->Run());
@@ -925,11 +943,11 @@ TEST_F(PackMediaSequenceCalculatorTest, TestTooLargeInputFailsSoftly) {
   for (int i = 0; i < num_timesteps; ++i) {
     auto vf_ptr = ::absl::make_unique<std::vector<float>>(1000000, i);
     runner_->MutableInputs()
-        ->Tag("FLOAT_FEATURE_TEST")
+        ->Tag(kFloatFeatureTestTag)
         .packets.push_back(Adopt(vf_ptr.release()).At(Timestamp(i)));
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
   ASSERT_FALSE(runner_->Run().ok());
 }

mediapipe/calculators/tensorflow/tensor_to_matrix_calculator_test.cc

@@ -26,6 +26,8 @@ namespace mediapipe {
 namespace tf = ::tensorflow;
 namespace {
 
+constexpr char kReferenceTag[] = "REFERENCE";
+
 constexpr char kMatrix[] = "MATRIX";
 constexpr char kTensor[] = "TENSOR";
 
@@ -68,7 +70,8 @@ class TensorToMatrixCalculatorTest : public ::testing::Test {
     if (include_rate) {
       header->set_packet_rate(1.0);
     }
-    runner_->MutableInputs()->Tag("REFERENCE").header = Adopt(header.release());
+    runner_->MutableInputs()->Tag(kReferenceTag).header =
+        Adopt(header.release());
   }
 
   std::unique_ptr<CalculatorRunner> runner_;

mediapipe/calculators/tensorflow/tensor_to_vector_string_calculator.cc

@@ -0,0 +1,118 @@
+// Copyright 2019 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Calculator converts from one-dimensional Tensor of DT_STRING to
+// vector<std::string> OR from (batched) two-dimensional Tensor of DT_STRING to
+// vector<vector<std::string>.
+
+#include "mediapipe/calculators/tensorflow/tensor_to_vector_string_calculator_options.pb.h"
+#include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/port/ret_check.h"
+#include "mediapipe/framework/port/status.h"
+#include "tensorflow/core/framework/tensor.h"
+#include "tensorflow/core/framework/types.h"
+
+namespace mediapipe {
+
+namespace tf = ::tensorflow;
+
+class TensorToVectorStringCalculator : public CalculatorBase {
+ public:
+  static absl::Status GetContract(CalculatorContract* cc);
+
+  absl::Status Open(CalculatorContext* cc) override;
+  absl::Status Process(CalculatorContext* cc) override;
+
+ private:
+  TensorToVectorStringCalculatorOptions options_;
+};
+REGISTER_CALCULATOR(TensorToVectorStringCalculator);
+
+absl::Status TensorToVectorStringCalculator::GetContract(
+    CalculatorContract* cc) {
+  // Start with only one input packet.
+  RET_CHECK_EQ(cc->Inputs().NumEntries(), 1)
+      << "Only one input stream is supported.";
+  cc->Inputs().Index(0).Set<tf::Tensor>(
+      // Input Tensor
+  );
+  RET_CHECK_EQ(cc->Outputs().NumEntries(), 1)
+      << "Only one output stream is supported.";
+  const auto& options = cc->Options<TensorToVectorStringCalculatorOptions>();
+  if (options.tensor_is_2d()) {
+    RET_CHECK(!options.flatten_nd());
+    cc->Outputs().Index(0).Set<std::vector<std::vector<std::string>>>(
+        /* "Output vector<vector<std::string>>." */);
+  } else {
+    cc->Outputs().Index(0).Set<std::vector<std::string>>(
+        // Output vector<std::string>.
+    );
+  }
+  return absl::OkStatus();
+}
+
+absl::Status TensorToVectorStringCalculator::Open(CalculatorContext* cc) {
+  options_ = cc->Options<TensorToVectorStringCalculatorOptions>();
+
+  // Inform mediapipe that this calculator produces an output at time t for
+  // each input received at time t (i.e. this calculator does not buffer
+  // inputs). This enables mediapipe to propagate time of arrival estimates in
+  // mediapipe graphs through this calculator.
+  cc->SetOffset(/*offset=*/0);
+
+  return absl::OkStatus();
+}
+
+absl::Status TensorToVectorStringCalculator::Process(CalculatorContext* cc) {
+  const tf::Tensor& input_tensor =
+      cc->Inputs().Index(0).Value().Get<tf::Tensor>();
+  RET_CHECK(tf::DT_STRING == input_tensor.dtype())
+      << "expected DT_STRING input but got "
+      << tensorflow::DataTypeString(input_tensor.dtype());
+
+  if (options_.tensor_is_2d()) {
+    RET_CHECK(2 == input_tensor.dims())
+        << "Expected 2-dimensional Tensor, but the tensor shape is: "
+        << input_tensor.shape().DebugString();
+    auto output = absl::make_unique<std::vector<std::vector<std::string>>>(
+        input_tensor.dim_size(0),
+        std::vector<std::string>(input_tensor.dim_size(1)));
+    for (int i = 0; i < input_tensor.dim_size(0); ++i) {
+      auto& instance_output = output->at(i);
+      const auto& slice =
+          input_tensor.Slice(i, i + 1).unaligned_flat<tensorflow::tstring>();
+      for (int j = 0; j < input_tensor.dim_size(1); ++j) {
+        instance_output.at(j) = slice(j);
+      }
+    }
+    cc->Outputs().Index(0).Add(output.release(), cc->InputTimestamp());
+  } else {
+    if (!options_.flatten_nd()) {
+      RET_CHECK(1 == input_tensor.dims())
+          << "`flatten_nd` is not set. Expected 1-dimensional Tensor, but the "
+          << "tensor shape is: " << input_tensor.shape().DebugString();
+    }
+    auto output =
+        absl::make_unique<std::vector<std::string>>(input_tensor.NumElements());
+    const auto& tensor_values = input_tensor.flat<tensorflow::tstring>();
+    for (int i = 0; i < input_tensor.NumElements(); ++i) {
+      output->at(i) = tensor_values(i);
+    }
+    cc->Outputs().Index(0).Add(output.release(), cc->InputTimestamp());
+  }
+
+  return absl::OkStatus();
+}
+
+}  // namespace mediapipe

mediapipe/calculators/tensorflow/tensor_to_vector_string_calculator_options.proto

@@ -0,0 +1,33 @@
+// Copyright 2019 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto2";
+
+package mediapipe;
+
+import "mediapipe/framework/calculator.proto";
+
+message TensorToVectorStringCalculatorOptions {
+  extend mediapipe.CalculatorOptions {
+    optional TensorToVectorStringCalculatorOptions ext = 386534187;
+  }
+
+  // If true, unpack a 2d tensor (matrix) into a vector<vector<string>>. If
+  // false, convert a 1d tensor (vector) into a vector<string>.
+  optional bool tensor_is_2d = 1 [default = false];
+
+  // If true, an N-D tensor will be flattened to a vector<string>. This is
+  // exclusive with tensor_is_2d.
+  optional bool flatten_nd = 2 [default = false];
+}

mediapipe/calculators/tensorflow/tensor_to_vector_string_calculator_test.cc

@@ -0,0 +1,130 @@
+// Copyright 2018 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "mediapipe/calculators/tensorflow/tensor_to_vector_string_calculator_options.pb.h"
+#include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/calculator_runner.h"
+#include "mediapipe/framework/port/gtest.h"
+#include "tensorflow/core/framework/tensor.h"
+#include "tensorflow/core/framework/types.pb.h"
+
+namespace mediapipe {
+
+namespace {
+
+namespace tf = ::tensorflow;
+
+class TensorToVectorStringCalculatorTest : public ::testing::Test {
+ protected:
+  void SetUpRunner(const bool tensor_is_2d, const bool flatten_nd) {
+    CalculatorGraphConfig::Node config;
+    config.set_calculator("TensorToVectorStringCalculator");
+    config.add_input_stream("input_tensor");
+    config.add_output_stream("output_tensor");
+    auto options = config.mutable_options()->MutableExtension(
+        TensorToVectorStringCalculatorOptions::ext);
+    options->set_tensor_is_2d(tensor_is_2d);
+    options->set_flatten_nd(flatten_nd);
+    runner_ = absl::make_unique<CalculatorRunner>(config);
+  }
+
+  std::unique_ptr<CalculatorRunner> runner_;
+};
+
+TEST_F(TensorToVectorStringCalculatorTest, ConvertsToVectorFloat) {
+  SetUpRunner(false, false);
+  const tf::TensorShape tensor_shape(std::vector<tf::int64>{5});
+  auto tensor = absl::make_unique<tf::Tensor>(tf::DT_STRING, tensor_shape);
+  auto tensor_vec = tensor->vec<tensorflow::tstring>();
+  for (int i = 0; i < 5; ++i) {
+    tensor_vec(i) = absl::StrCat("foo", i);
+  }
+
+  const int64 time = 1234;
+  runner_->MutableInputs()->Index(0).packets.push_back(
+      Adopt(tensor.release()).At(Timestamp(time)));
+
+  EXPECT_TRUE(runner_->Run().ok());
+  const std::vector<Packet>& output_packets =
+      runner_->Outputs().Index(0).packets;
+  EXPECT_EQ(1, output_packets.size());
+  EXPECT_EQ(time, output_packets[0].Timestamp().Value());
+  const std::vector<std::string>& output_vector =
+      output_packets[0].Get<std::vector<std::string>>();
+
+  EXPECT_EQ(5, output_vector.size());
+  for (int i = 0; i < 5; ++i) {
+    const std::string expected = absl::StrCat("foo", i);
+    EXPECT_EQ(expected, output_vector[i]);
+  }
+}
+
+TEST_F(TensorToVectorStringCalculatorTest, ConvertsBatchedToVectorVectorFloat) {
+  SetUpRunner(true, false);
+  const tf::TensorShape tensor_shape(std::vector<tf::int64>{1, 5});
+  auto tensor = absl::make_unique<tf::Tensor>(tf::DT_STRING, tensor_shape);
+  auto slice = tensor->Slice(0, 1).flat<tensorflow::tstring>();
+  for (int i = 0; i < 5; ++i) {
+    slice(i) = absl::StrCat("foo", i);
+  }
+
+  const int64 time = 1234;
+  runner_->MutableInputs()->Index(0).packets.push_back(
+      Adopt(tensor.release()).At(Timestamp(time)));
+
+  EXPECT_TRUE(runner_->Run().ok());
+  const std::vector<Packet>& output_packets =
+      runner_->Outputs().Index(0).packets;
+  EXPECT_EQ(1, output_packets.size());
+  EXPECT_EQ(time, output_packets[0].Timestamp().Value());
+  const std::vector<std::vector<std::string>>& output_vectors =
+      output_packets[0].Get<std::vector<std::vector<std::string>>>();
+  ASSERT_EQ(1, output_vectors.size());
+  const std::vector<std::string>& output_vector = output_vectors[0];
+  EXPECT_EQ(5, output_vector.size());
+  for (int i = 0; i < 5; ++i) {
+    const std::string expected = absl::StrCat("foo", i);
+    EXPECT_EQ(expected, output_vector[i]);
+  }
+}
+
+TEST_F(TensorToVectorStringCalculatorTest, FlattenShouldTakeAllDimensions) {
+  SetUpRunner(false, true);
+  const tf::TensorShape tensor_shape(std::vector<tf::int64>{2, 2, 2});
+  auto tensor = absl::make_unique<tf::Tensor>(tf::DT_STRING, tensor_shape);
+  auto slice = tensor->flat<tensorflow::tstring>();
+  for (int i = 0; i < 2 * 2 * 2; ++i) {
+    slice(i) = absl::StrCat("foo", i);
+  }
+
+  const int64 time = 1234;
+  runner_->MutableInputs()->Index(0).packets.push_back(
+      Adopt(tensor.release()).At(Timestamp(time)));
+
+  EXPECT_TRUE(runner_->Run().ok());
+  const std::vector<Packet>& output_packets =
+      runner_->Outputs().Index(0).packets;
+  EXPECT_EQ(1, output_packets.size());
+  EXPECT_EQ(time, output_packets[0].Timestamp().Value());
+  const std::vector<std::string>& output_vector =
+      output_packets[0].Get<std::vector<std::string>>();
+  EXPECT_EQ(2 * 2 * 2, output_vector.size());
+  for (int i = 0; i < 2 * 2 * 2; ++i) {
+    const std::string expected = absl::StrCat("foo", i);
+    EXPECT_EQ(expected, output_vector[i]);
+  }
+}
+
+}  // namespace
+}  // namespace mediapipe

mediapipe/calculators/tensorflow/tensorflow_inference_calculator.cc

@@ -49,6 +49,11 @@ namespace tf = ::tensorflow;
 namespace mediapipe {
 
 namespace {
+
+constexpr char kRecurrentInitTensorsTag[] = "RECURRENT_INIT_TENSORS";
+constexpr char kSessionTag[] = "SESSION";
+constexpr char kSessionBundleTag[] = "SESSION_BUNDLE";
+
 // This is a simple implementation of a semaphore using standard C++ libraries.
 // It is supposed to be used only by TensorflowInferenceCalculator to throttle
 // the concurrent calls of Tensorflow Session::Run. This is useful when multiple
@@ -252,10 +257,10 @@ class TensorFlowInferenceCalculator : public CalculatorBase {
     }
     // A mediapipe::TensorFlowSession with a model loaded and ready for use.
     // For this calculator it must include a tag_to_tensor_map.
-    cc->InputSidePackets().Tag("SESSION").Set<TensorFlowSession>();
+    cc->InputSidePackets().Tag(kSessionTag).Set<TensorFlowSession>();
-    if (cc->InputSidePackets().HasTag("RECURRENT_INIT_TENSORS")) {
+    if (cc->InputSidePackets().HasTag(kRecurrentInitTensorsTag)) {
       cc->InputSidePackets()
-          .Tag("RECURRENT_INIT_TENSORS")
+          .Tag(kRecurrentInitTensorsTag)
           .Set<std::unique_ptr<std::map<std::string, tf::Tensor>>>();
     }
     return absl::OkStatus();
@@ -265,11 +270,11 @@ class TensorFlowInferenceCalculator : public CalculatorBase {
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_) {
     std::unique_ptr<InferenceState> inference_state =
         absl::make_unique<InferenceState>();
-    if (cc->InputSidePackets().HasTag("RECURRENT_INIT_TENSORS") &&
+    if (cc->InputSidePackets().HasTag(kRecurrentInitTensorsTag) &&
-        !cc->InputSidePackets().Tag("RECURRENT_INIT_TENSORS").IsEmpty()) {
+        !cc->InputSidePackets().Tag(kRecurrentInitTensorsTag).IsEmpty()) {
       std::map<std::string, tf::Tensor>* init_tensor_map;
       init_tensor_map = GetFromUniquePtr<std::map<std::string, tf::Tensor>>(
-          cc->InputSidePackets().Tag("RECURRENT_INIT_TENSORS"));
+          cc->InputSidePackets().Tag(kRecurrentInitTensorsTag));
       for (const auto& p : *init_tensor_map) {
         inference_state->input_tensor_batches_[p.first].emplace_back(p.second);
       }
@@ -280,13 +285,13 @@ class TensorFlowInferenceCalculator : public CalculatorBase {
   absl::Status Open(CalculatorContext* cc) override {
     options_ = cc->Options<TensorFlowInferenceCalculatorOptions>();
 
-    RET_CHECK(cc->InputSidePackets().HasTag("SESSION"));
+    RET_CHECK(cc->InputSidePackets().HasTag(kSessionTag));
     session_ = cc->InputSidePackets()
-                   .Tag("SESSION")
+                   .Tag(kSessionTag)
                    .Get<TensorFlowSession>()
                    .session.get();
     tag_to_tensor_map_ = cc->InputSidePackets()
-                             .Tag("SESSION")
+                             .Tag(kSessionTag)
                              .Get<TensorFlowSession>()
                              .tag_to_tensor_map;
 

mediapipe/calculators/tensorflow/tensorflow_inference_calculator_test.cc

@@ -41,6 +41,11 @@ namespace mediapipe {
 namespace tf = ::tensorflow;
 
 namespace {
+
+constexpr char kMultipliedTag[] = "MULTIPLIED";
+constexpr char kBTag[] = "B";
+constexpr char kSessionTag[] = "SESSION";
+
 std::string GetGraphDefPath() {
 #ifdef __APPLE__
   char path[1024];
@@ -86,8 +91,8 @@ class TensorflowInferenceCalculatorTest : public ::testing::Test {
     MEDIAPIPE_CHECK_OK(tool::RunGenerateAndValidateTypes(
         "TensorFlowSessionFromFrozenGraphGenerator", extendable_options,
         input_side_packets, &output_side_packets));
-    runner_->MutableSidePackets()->Tag("SESSION") =
+    runner_->MutableSidePackets()->Tag(kSessionTag) =
-        output_side_packets.Tag("SESSION");
+        output_side_packets.Tag(kSessionTag);
   }
 
   Packet CreateTensorPacket(const std::vector<int32>& input, int64 time) {
@@ -140,7 +145,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetConstants) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_b =
-      runner_->Outputs().Tag("B").packets;
+      runner_->Outputs().Tag(kBTag).packets;
   ASSERT_EQ(output_packets_b.size(), 1);
   const tf::Tensor& tensor_b = output_packets_b[0].Get<tf::Tensor>();
   tf::TensorShape expected_shape({1, 3});
@@ -148,7 +153,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetConstants) {
   tf::test::ExpectTensorEqual<int32>(expected_tensor, tensor_b);
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(1, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   expected_tensor = tf::test::AsTensor<int32>({0, 0, 0}, expected_shape);
@@ -181,7 +186,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetComputed) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(1, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   tf::TensorShape expected_shape({3});
@@ -220,7 +225,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetComputed_MaxInFlight) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(1, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   tf::TensorShape expected_shape({3});
@@ -274,7 +279,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetMultiBatchComputed) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(2, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   auto expected_tensor = tf::test::AsTensor<int32>({6, 8, 10});
@@ -311,7 +316,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetMultiBatchComputed_MaxInFlight) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(2, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   auto expected_tensor = tf::test::AsTensor<int32>({6, 8, 10});
@@ -351,7 +356,7 @@ TEST_F(TensorflowInferenceCalculatorTest,
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(3, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   auto expected_tensor = tf::test::AsTensor<int32>({6, 8, 10});
@@ -392,7 +397,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetSingleBatchComputed) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(2, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   auto expected_tensor = tf::test::AsTensor<int32>({6, 8, 10});
@@ -430,7 +435,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetCloseBatchComputed) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(2, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   auto expected_tensor = tf::test::AsTensor<int32>({6, 8, 10});
@@ -481,7 +486,7 @@ TEST_F(TensorflowInferenceCalculatorTest, GetBatchComputed_MaxInFlight) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(5, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   auto expected_tensor = tf::test::AsTensor<int32>({6, 8, 10});
@@ -528,7 +533,7 @@ TEST_F(TensorflowInferenceCalculatorTest, TestRecurrentStates) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(2, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   LOG(INFO) << "timestamp: " << 0;
@@ -569,7 +574,7 @@ TEST_F(TensorflowInferenceCalculatorTest, TestRecurrentStateOverride) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(2, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   LOG(INFO) << "timestamp: " << 0;
@@ -662,7 +667,7 @@ TEST_F(TensorflowInferenceCalculatorTest, MissingInputFeature_Skip) {
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(0, output_packets_mult.size());
 }
 
@@ -691,7 +696,7 @@ TEST_F(TensorflowInferenceCalculatorTest,
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets_mult =
-      runner_->Outputs().Tag("MULTIPLIED").packets;
+      runner_->Outputs().Tag(kMultipliedTag).packets;
   ASSERT_EQ(1, output_packets_mult.size());
   const tf::Tensor& tensor_mult = output_packets_mult[0].Get<tf::Tensor>();
   auto expected_tensor = tf::test::AsTensor<int32>({9, 12, 15});

mediapipe/calculators/tensorflow/tensorflow_session_from_frozen_graph_calculator.cc

@@ -47,6 +47,11 @@ namespace mediapipe {
 namespace tf = ::tensorflow;
 
 namespace {
+
+constexpr char kSessionTag[] = "SESSION";
+constexpr char kStringModelFilePathTag[] = "STRING_MODEL_FILE_PATH";
+constexpr char kStringModelTag[] = "STRING_MODEL";
+
 // Updates the graph nodes to use the device as specified by device_id.
 void SetPreferredDevice(tf::GraphDef* graph_def, absl::string_view device_id) {
   for (auto& node : *graph_def->mutable_node()) {
@@ -64,27 +69,29 @@ class TensorFlowSessionFromFrozenGraphCalculator : public CalculatorBase {
         cc->Options<TensorFlowSessionFromFrozenGraphCalculatorOptions>();
     bool has_exactly_one_model =
         !options.graph_proto_path().empty()
-            ? !(cc->InputSidePackets().HasTag("STRING_MODEL") |
+            ? !(cc->InputSidePackets().HasTag(kStringModelTag) |
-                cc->InputSidePackets().HasTag("STRING_MODEL_FILE_PATH"))
+                cc->InputSidePackets().HasTag(kStringModelFilePathTag))
-            : (cc->InputSidePackets().HasTag("STRING_MODEL") ^
+            : (cc->InputSidePackets().HasTag(kStringModelTag) ^
-               cc->InputSidePackets().HasTag("STRING_MODEL_FILE_PATH"));
+               cc->InputSidePackets().HasTag(kStringModelFilePathTag));
     RET_CHECK(has_exactly_one_model)
         << "Must have exactly one of graph_proto_path in options or "
            "input_side_packets STRING_MODEL or STRING_MODEL_FILE_PATH";
-    if (cc->InputSidePackets().HasTag("STRING_MODEL")) {
+    if (cc->InputSidePackets().HasTag(kStringModelTag)) {
       cc->InputSidePackets()
-          .Tag("STRING_MODEL")
+          .Tag(kStringModelTag)
           .Set<std::string>(
               // String model from embedded path
           );
-    } else if (cc->InputSidePackets().HasTag("STRING_MODEL_FILE_PATH")) {
+    } else if (cc->InputSidePackets().HasTag(kStringModelFilePathTag)) {
       cc->InputSidePackets()
-          .Tag("STRING_MODEL_FILE_PATH")
+          .Tag(kStringModelFilePathTag)
           .Set<std::string>(
               // Filename of std::string model.
           );
     }
-    cc->OutputSidePackets().Tag("SESSION").Set<TensorFlowSession>(
+    cc->OutputSidePackets()
+        .Tag(kSessionTag)
+        .Set<TensorFlowSession>(
             // A TensorFlow model loaded and ready for use along with
             // a map from tags to tensor names.
         );
@@ -111,12 +118,12 @@ class TensorFlowSessionFromFrozenGraphCalculator : public CalculatorBase {
     session->session.reset(tf::NewSession(session_options));
 
     std::string graph_def_serialized;
-    if (cc->InputSidePackets().HasTag("STRING_MODEL")) {
+    if (cc->InputSidePackets().HasTag(kStringModelTag)) {
       graph_def_serialized =
-          cc->InputSidePackets().Tag("STRING_MODEL").Get<std::string>();
+          cc->InputSidePackets().Tag(kStringModelTag).Get<std::string>();
-    } else if (cc->InputSidePackets().HasTag("STRING_MODEL_FILE_PATH")) {
+    } else if (cc->InputSidePackets().HasTag(kStringModelFilePathTag)) {
       const std::string& frozen_graph = cc->InputSidePackets()
-                                            .Tag("STRING_MODEL_FILE_PATH")
+                                            .Tag(kStringModelFilePathTag)
                                             .Get<std::string>();
       RET_CHECK_OK(
           mediapipe::file::GetContents(frozen_graph, &graph_def_serialized));
@@ -147,7 +154,7 @@ class TensorFlowSessionFromFrozenGraphCalculator : public CalculatorBase {
       RET_CHECK(tf_status.ok()) << "Run failed: " << tf_status.ToString();
     }
 
-    cc->OutputSidePackets().Tag("SESSION").Set(Adopt(session.release()));
+    cc->OutputSidePackets().Tag(kSessionTag).Set(Adopt(session.release()));
     const uint64 end_time = absl::ToUnixMicros(clock->TimeNow());
     LOG(INFO) << "Loaded frozen model in: " << end_time - start_time
               << " microseconds.";

mediapipe/calculators/tensorflow/tensorflow_session_from_frozen_graph_calculator_test.cc

@@ -37,6 +37,10 @@ namespace {
 
 namespace tf = ::tensorflow;
 
+constexpr char kStringModelFilePathTag[] = "STRING_MODEL_FILE_PATH";
+constexpr char kStringModelTag[] = "STRING_MODEL";
+constexpr char kSessionTag[] = "SESSION";
+
 std::string GetGraphDefPath() {
   return mediapipe::file::JoinPath("./",
                                    "mediapipe/calculators/tensorflow/"
@@ -112,7 +116,7 @@ TEST_F(TensorFlowSessionFromFrozenGraphCalculatorTest,
 
   MP_ASSERT_OK(runner.Run());
   const TensorFlowSession& session =
-      runner.OutputSidePackets().Tag("SESSION").Get<TensorFlowSession>();
+      runner.OutputSidePackets().Tag(kSessionTag).Get<TensorFlowSession>();
   VerifySignatureMap(session);
 }
 
@@ -190,12 +194,12 @@ TEST_F(TensorFlowSessionFromFrozenGraphCalculatorTest,
   std::string serialized_graph_contents;
   MP_EXPECT_OK(mediapipe::file::GetContents(GetGraphDefPath(),
                                             &serialized_graph_contents));
-  runner.MutableSidePackets()->Tag("STRING_MODEL") =
+  runner.MutableSidePackets()->Tag(kStringModelTag) =
       Adopt(new std::string(serialized_graph_contents));
   MP_ASSERT_OK(runner.Run());
 
   const TensorFlowSession& session =
-      runner.OutputSidePackets().Tag("SESSION").Get<TensorFlowSession>();
+      runner.OutputSidePackets().Tag(kSessionTag).Get<TensorFlowSession>();
   VerifySignatureMap(session);
 }
 
@@ -213,12 +217,12 @@ TEST_F(
           }
         })",
                                            calculator_options_->DebugString()));
-  runner.MutableSidePackets()->Tag("STRING_MODEL_FILE_PATH") =
+  runner.MutableSidePackets()->Tag(kStringModelFilePathTag) =
       Adopt(new std::string(GetGraphDefPath()));
   MP_ASSERT_OK(runner.Run());
 
   const TensorFlowSession& session =
-      runner.OutputSidePackets().Tag("SESSION").Get<TensorFlowSession>();
+      runner.OutputSidePackets().Tag(kSessionTag).Get<TensorFlowSession>();
   VerifySignatureMap(session);
 }
 
@@ -234,7 +238,7 @@ TEST_F(TensorFlowSessionFromFrozenGraphCalculatorTest,
           }
         })",
                                            calculator_options_->DebugString()));
-  runner.MutableSidePackets()->Tag("STRING_MODEL_FILE_PATH") =
+  runner.MutableSidePackets()->Tag(kStringModelFilePathTag) =
       Adopt(new std::string(GetGraphDefPath()));
   auto run_status = runner.Run();
   EXPECT_THAT(
@@ -255,12 +259,12 @@ TEST_F(TensorFlowSessionFromFrozenGraphCalculatorTest,
           }
         })",
                                            calculator_options_->DebugString()));
-  runner.MutableSidePackets()->Tag("STRING_MODEL_FILE_PATH") =
+  runner.MutableSidePackets()->Tag(kStringModelFilePathTag) =
       Adopt(new std::string(GetGraphDefPath()));
   std::string serialized_graph_contents;
   MP_EXPECT_OK(mediapipe::file::GetContents(GetGraphDefPath(),
                                             &serialized_graph_contents));
-  runner.MutableSidePackets()->Tag("STRING_MODEL") =
+  runner.MutableSidePackets()->Tag(kStringModelTag) =
       Adopt(new std::string(serialized_graph_contents));
   auto run_status = runner.Run();
   EXPECT_THAT(
@@ -282,12 +286,12 @@ TEST_F(TensorFlowSessionFromFrozenGraphCalculatorTest,
           }
         })",
                                            calculator_options_->DebugString()));
-  runner.MutableSidePackets()->Tag("STRING_MODEL_FILE_PATH") =
+  runner.MutableSidePackets()->Tag(kStringModelFilePathTag) =
       Adopt(new std::string(GetGraphDefPath()));
   std::string serialized_graph_contents;
   MP_EXPECT_OK(mediapipe::file::GetContents(GetGraphDefPath(),
                                             &serialized_graph_contents));
-  runner.MutableSidePackets()->Tag("STRING_MODEL") =
+  runner.MutableSidePackets()->Tag(kStringModelTag) =
       Adopt(new std::string(serialized_graph_contents));
   auto run_status = runner.Run();
   EXPECT_THAT(
@@ -310,7 +314,7 @@ TEST_F(TensorFlowSessionFromFrozenGraphCalculatorTest,
   MP_ASSERT_OK(runner.Run());
 
   const TensorFlowSession& session =
-      runner.OutputSidePackets().Tag("SESSION").Get<TensorFlowSession>();
+      runner.OutputSidePackets().Tag(kSessionTag).Get<TensorFlowSession>();
   VerifySignatureMap(session);
 }
 

mediapipe/calculators/tensorflow/tensorflow_session_from_frozen_graph_generator.cc

@@ -43,6 +43,11 @@ namespace mediapipe {
 namespace tf = ::tensorflow;
 
 namespace {
+
+constexpr char kSessionTag[] = "SESSION";
+constexpr char kStringModelFilePathTag[] = "STRING_MODEL_FILE_PATH";
+constexpr char kStringModelTag[] = "STRING_MODEL";
+
 // Updates the graph nodes to use the device as specified by device_id.
 void SetPreferredDevice(tf::GraphDef* graph_def, absl::string_view device_id) {
   for (auto& node : *graph_def->mutable_node()) {
@@ -64,25 +69,26 @@ class TensorFlowSessionFromFrozenGraphGenerator : public PacketGenerator {
         TensorFlowSessionFromFrozenGraphGeneratorOptions::ext);
     bool has_exactly_one_model =
         !options.graph_proto_path().empty()
-            ? !(input_side_packets->HasTag("STRING_MODEL") |
+            ? !(input_side_packets->HasTag(kStringModelTag) |
-                input_side_packets->HasTag("STRING_MODEL_FILE_PATH"))
+                input_side_packets->HasTag(kStringModelFilePathTag))
-            : (input_side_packets->HasTag("STRING_MODEL") ^
+            : (input_side_packets->HasTag(kStringModelTag) ^
-               input_side_packets->HasTag("STRING_MODEL_FILE_PATH"));
+               input_side_packets->HasTag(kStringModelFilePathTag));
     RET_CHECK(has_exactly_one_model)
         << "Must have exactly one of graph_proto_path in options or "
            "input_side_packets STRING_MODEL or STRING_MODEL_FILE_PATH";
-    if (input_side_packets->HasTag("STRING_MODEL")) {
+    if (input_side_packets->HasTag(kStringModelTag)) {
-      input_side_packets->Tag("STRING_MODEL")
+      input_side_packets->Tag(kStringModelTag)
           .Set<std::string>(
               // String model from embedded path
           );
-    } else if (input_side_packets->HasTag("STRING_MODEL_FILE_PATH")) {
+    } else if (input_side_packets->HasTag(kStringModelFilePathTag)) {
-      input_side_packets->Tag("STRING_MODEL_FILE_PATH")
+      input_side_packets->Tag(kStringModelFilePathTag)
           .Set<std::string>(
               // Filename of std::string model.
           );
     }
-    output_side_packets->Tag("SESSION").Set<TensorFlowSession>(
+    output_side_packets->Tag(kSessionTag)
+        .Set<TensorFlowSession>(
             // A TensorFlow model loaded and ready for use along with
             // a map from tags to tensor names.
         );
@@ -112,12 +118,12 @@ class TensorFlowSessionFromFrozenGraphGenerator : public PacketGenerator {
     session->session.reset(tf::NewSession(session_options));
 
     std::string graph_def_serialized;
-    if (input_side_packets.HasTag("STRING_MODEL")) {
+    if (input_side_packets.HasTag(kStringModelTag)) {
       graph_def_serialized =
-          input_side_packets.Tag("STRING_MODEL").Get<std::string>();
+          input_side_packets.Tag(kStringModelTag).Get<std::string>();
-    } else if (input_side_packets.HasTag("STRING_MODEL_FILE_PATH")) {
+    } else if (input_side_packets.HasTag(kStringModelFilePathTag)) {
       const std::string& frozen_graph =
-          input_side_packets.Tag("STRING_MODEL_FILE_PATH").Get<std::string>();
+          input_side_packets.Tag(kStringModelFilePathTag).Get<std::string>();
       RET_CHECK_OK(
           mediapipe::file::GetContents(frozen_graph, &graph_def_serialized));
     } else {
@@ -147,7 +153,7 @@ class TensorFlowSessionFromFrozenGraphGenerator : public PacketGenerator {
       RET_CHECK(tf_status.ok()) << "Run failed: " << tf_status.ToString();
     }
 
-    output_side_packets->Tag("SESSION") = Adopt(session.release());
+    output_side_packets->Tag(kSessionTag) = Adopt(session.release());
     const uint64 end_time = absl::ToUnixMicros(clock->TimeNow());
     LOG(INFO) << "Loaded frozen model in: " << end_time - start_time
               << " microseconds.";

mediapipe/calculators/tensorflow/tensorflow_session_from_frozen_graph_generator_test.cc

@@ -37,6 +37,10 @@ namespace {
 
 namespace tf = ::tensorflow;
 
+constexpr char kStringModelFilePathTag[] = "STRING_MODEL_FILE_PATH";
+constexpr char kStringModelTag[] = "STRING_MODEL";
+constexpr char kSessionTag[] = "SESSION";
+
 std::string GetGraphDefPath() {
   return mediapipe::file::JoinPath("./",
                                    "mediapipe/calculators/tensorflow/"
@@ -72,7 +76,7 @@ class TensorFlowSessionFromFrozenGraphGeneratorTest : public ::testing::Test {
 
   void VerifySignatureMap(PacketSet* output_side_packets) {
     const TensorFlowSession& session =
-        output_side_packets->Tag("SESSION").Get<TensorFlowSession>();
+        output_side_packets->Tag(kSessionTag).Get<TensorFlowSession>();
     // Session must be set.
     ASSERT_NE(session.session, nullptr);
 
@@ -179,7 +183,7 @@ TEST_F(TensorFlowSessionFromFrozenGraphGeneratorTest,
   MP_EXPECT_OK(mediapipe::file::GetContents(GetGraphDefPath(),
                                             &serialized_graph_contents));
   generator_options_->clear_graph_proto_path();
-  input_side_packets.Tag("STRING_MODEL") =
+  input_side_packets.Tag(kStringModelTag) =
       Adopt(new std::string(serialized_graph_contents));
   absl::Status run_status = tool::RunGenerateAndValidateTypes(
       "TensorFlowSessionFromFrozenGraphGenerator", extendable_options_,
@@ -196,7 +200,7 @@ TEST_F(
   PacketSet output_side_packets(
       tool::CreateTagMap({"SESSION:session"}).value());
   generator_options_->clear_graph_proto_path();
-  input_side_packets.Tag("STRING_MODEL_FILE_PATH") =
+  input_side_packets.Tag(kStringModelFilePathTag) =
       Adopt(new std::string(GetGraphDefPath()));
   absl::Status run_status = tool::RunGenerateAndValidateTypes(
       "TensorFlowSessionFromFrozenGraphGenerator", extendable_options_,
@@ -211,7 +215,7 @@ TEST_F(TensorFlowSessionFromFrozenGraphGeneratorTest,
       tool::CreateTagMap({"STRING_MODEL_FILE_PATH:model_path"}).value());
   PacketSet output_side_packets(
       tool::CreateTagMap({"SESSION:session"}).value());
-  input_side_packets.Tag("STRING_MODEL_FILE_PATH") =
+  input_side_packets.Tag(kStringModelFilePathTag) =
       Adopt(new std::string(GetGraphDefPath()));
   absl::Status run_status = tool::RunGenerateAndValidateTypes(
       "TensorFlowSessionFromFrozenGraphGenerator", extendable_options_,
@@ -233,9 +237,9 @@ TEST_F(TensorFlowSessionFromFrozenGraphGeneratorTest,
   std::string serialized_graph_contents;
   MP_EXPECT_OK(mediapipe::file::GetContents(GetGraphDefPath(),
                                             &serialized_graph_contents));
-  input_side_packets.Tag("STRING_MODEL") =
+  input_side_packets.Tag(kStringModelTag) =
       Adopt(new std::string(serialized_graph_contents));
-  input_side_packets.Tag("STRING_MODEL_FILE_PATH") =
+  input_side_packets.Tag(kStringModelFilePathTag) =
       Adopt(new std::string(GetGraphDefPath()));
 
   absl::Status run_status = tool::RunGenerateAndValidateTypes(
@@ -258,9 +262,9 @@ TEST_F(TensorFlowSessionFromFrozenGraphGeneratorTest,
   std::string serialized_graph_contents;
   MP_EXPECT_OK(mediapipe::file::GetContents(GetGraphDefPath(),
                                             &serialized_graph_contents));
-  input_side_packets.Tag("STRING_MODEL") =
+  input_side_packets.Tag(kStringModelTag) =
       Adopt(new std::string(serialized_graph_contents));
-  input_side_packets.Tag("STRING_MODEL_FILE_PATH") =
+  input_side_packets.Tag(kStringModelFilePathTag) =
       Adopt(new std::string(GetGraphDefPath()));
   generator_options_->clear_graph_proto_path();
 

mediapipe/calculators/tensorflow/tensorflow_session_from_saved_model_calculator.cc

@@ -31,6 +31,9 @@
 namespace mediapipe {
 
 namespace {
+
+constexpr char kSessionTag[] = "SESSION";
+
 static constexpr char kStringSavedModelPath[] = "STRING_SAVED_MODEL_PATH";
 
 // Given the path to a directory containing multiple tensorflow saved models
@@ -108,7 +111,7 @@ class TensorFlowSessionFromSavedModelCalculator : public CalculatorBase {
       cc->InputSidePackets().Tag(kStringSavedModelPath).Set<std::string>();
     }
     // A TensorFlow model loaded and ready for use along with tensor
-    cc->OutputSidePackets().Tag("SESSION").Set<TensorFlowSession>();
+    cc->OutputSidePackets().Tag(kSessionTag).Set<TensorFlowSession>();
     return absl::OkStatus();
   }
 
@@ -160,7 +163,7 @@ class TensorFlowSessionFromSavedModelCalculator : public CalculatorBase {
           output_signature.first, options)] = output_signature.second.name();
     }
 
-    cc->OutputSidePackets().Tag("SESSION").Set(Adopt(session.release()));
+    cc->OutputSidePackets().Tag(kSessionTag).Set(Adopt(session.release()));
     return absl::OkStatus();
   }
 

mediapipe/calculators/tensorflow/tensorflow_session_from_saved_model_calculator_test.cc

@@ -35,6 +35,9 @@ namespace {
 
 namespace tf = ::tensorflow;
 
+constexpr char kStringSavedModelPathTag[] = "STRING_SAVED_MODEL_PATH";
+constexpr char kSessionTag[] = "SESSION";
+
 std::string GetSavedModelDir() {
   std::string out_path =
       file::JoinPath("./", "mediapipe/calculators/tensorflow/testdata/",
@@ -79,7 +82,7 @@ TEST_F(TensorFlowSessionFromSavedModelCalculatorTest,
                                            options_->DebugString()));
   MP_ASSERT_OK(runner.Run());
   const TensorFlowSession& session =
-      runner.OutputSidePackets().Tag("SESSION").Get<TensorFlowSession>();
+      runner.OutputSidePackets().Tag(kSessionTag).Get<TensorFlowSession>();
   // Session must be set.
   ASSERT_NE(session.session, nullptr);
 
@@ -119,11 +122,11 @@ TEST_F(TensorFlowSessionFromSavedModelCalculatorTest,
           }
         })",
                                            options_->DebugString()));
-  runner.MutableSidePackets()->Tag("STRING_SAVED_MODEL_PATH") =
+  runner.MutableSidePackets()->Tag(kStringSavedModelPathTag) =
       MakePacket<std::string>(GetSavedModelDir());
   MP_ASSERT_OK(runner.Run());
   const TensorFlowSession& session =
-      runner.OutputSidePackets().Tag("SESSION").Get<TensorFlowSession>();
+      runner.OutputSidePackets().Tag(kSessionTag).Get<TensorFlowSession>();
   // Session must be set.
   ASSERT_NE(session.session, nullptr);
 }
@@ -201,7 +204,7 @@ TEST_F(TensorFlowSessionFromSavedModelCalculatorTest,
                                            options_->DebugString()));
   MP_ASSERT_OK(runner.Run());
   const TensorFlowSession& session =
-      runner.OutputSidePackets().Tag("SESSION").Get<TensorFlowSession>();
+      runner.OutputSidePackets().Tag(kSessionTag).Get<TensorFlowSession>();
   // Session must be set.
   ASSERT_NE(session.session, nullptr);
 }
@@ -224,7 +227,7 @@ TEST_F(TensorFlowSessionFromSavedModelCalculatorTest,
                                            options_->DebugString()));
   MP_ASSERT_OK(runner.Run());
   const TensorFlowSession& session =
-      runner.OutputSidePackets().Tag("SESSION").Get<TensorFlowSession>();
+      runner.OutputSidePackets().Tag(kSessionTag).Get<TensorFlowSession>();
   // Session must be set.
   ASSERT_NE(session.session, nullptr);
   std::vector<tensorflow::DeviceAttributes> devices;

mediapipe/calculators/tensorflow/tensorflow_session_from_saved_model_generator.cc

@@ -33,6 +33,9 @@
 namespace mediapipe {
 
 namespace {
+
+constexpr char kSessionTag[] = "SESSION";
+
 static constexpr char kStringSavedModelPath[] = "STRING_SAVED_MODEL_PATH";
 
 // Given the path to a directory containing multiple tensorflow saved models
@@ -100,7 +103,7 @@ class TensorFlowSessionFromSavedModelGenerator : public PacketGenerator {
       input_side_packets->Tag(kStringSavedModelPath).Set<std::string>();
     }
     // A TensorFlow model loaded and ready for use along with tensor
-    output_side_packets->Tag("SESSION").Set<TensorFlowSession>();
+    output_side_packets->Tag(kSessionTag).Set<TensorFlowSession>();
     return absl::OkStatus();
   }
 
@@ -153,7 +156,7 @@ class TensorFlowSessionFromSavedModelGenerator : public PacketGenerator {
           output_signature.first, options)] = output_signature.second.name();
     }
 
-    output_side_packets->Tag("SESSION") = Adopt(session.release());
+    output_side_packets->Tag(kSessionTag) = Adopt(session.release());
     return absl::OkStatus();
   }
 };

mediapipe/calculators/tensorflow/tensorflow_session_from_saved_model_generator_test.cc

@@ -34,6 +34,9 @@ namespace {
 
 namespace tf = ::tensorflow;
 
+constexpr char kStringSavedModelPathTag[] = "STRING_SAVED_MODEL_PATH";
+constexpr char kSessionTag[] = "SESSION";
+
 std::string GetSavedModelDir() {
   std::string out_path =
       file::JoinPath("./", "mediapipe/calculators/tensorflow/testdata/",
@@ -75,7 +78,7 @@ TEST_F(TensorFlowSessionFromSavedModelGeneratorTest,
       input_side_packets, &output_side_packets);
   MP_EXPECT_OK(run_status) << run_status.message();
   const TensorFlowSession& session =
-      output_side_packets.Tag("SESSION").Get<TensorFlowSession>();
+      output_side_packets.Tag(kSessionTag).Get<TensorFlowSession>();
   // Session must be set.
   ASSERT_NE(session.session, nullptr);
 
@@ -107,7 +110,7 @@ TEST_F(TensorFlowSessionFromSavedModelGeneratorTest,
   generator_options_->clear_saved_model_path();
   PacketSet input_side_packets(
       tool::CreateTagMap({"STRING_SAVED_MODEL_PATH:saved_model_dir"}).value());
-  input_side_packets.Tag("STRING_SAVED_MODEL_PATH") =
+  input_side_packets.Tag(kStringSavedModelPathTag) =
       Adopt(new std::string(GetSavedModelDir()));
   PacketSet output_side_packets(
       tool::CreateTagMap({"SESSION:session"}).value());
@@ -116,7 +119,7 @@ TEST_F(TensorFlowSessionFromSavedModelGeneratorTest,
       input_side_packets, &output_side_packets);
   MP_EXPECT_OK(run_status) << run_status.message();
   const TensorFlowSession& session =
-      output_side_packets.Tag("SESSION").Get<TensorFlowSession>();
+      output_side_packets.Tag(kSessionTag).Get<TensorFlowSession>();
   // Session must be set.
   ASSERT_NE(session.session, nullptr);
 }
@@ -192,7 +195,7 @@ TEST_F(TensorFlowSessionFromSavedModelGeneratorTest,
       input_side_packets, &output_side_packets);
   MP_EXPECT_OK(run_status) << run_status.message();
   const TensorFlowSession& session =
-      output_side_packets.Tag("SESSION").Get<TensorFlowSession>();
+      output_side_packets.Tag(kSessionTag).Get<TensorFlowSession>();
   // Session must be set.
   ASSERT_NE(session.session, nullptr);
 }
@@ -213,7 +216,7 @@ TEST_F(TensorFlowSessionFromSavedModelGeneratorTest,
       input_side_packets, &output_side_packets);
   MP_EXPECT_OK(run_status) << run_status.message();
   const TensorFlowSession& session =
-      output_side_packets.Tag("SESSION").Get<TensorFlowSession>();
+      output_side_packets.Tag(kSessionTag).Get<TensorFlowSession>();
   // Session must be set.
   ASSERT_NE(session.session, nullptr);
   std::vector<tensorflow::DeviceAttributes> devices;

mediapipe/calculators/tensorflow/unpack_media_sequence_calculator_test.cc

@@ -33,6 +33,31 @@ namespace {
 namespace tf = ::tensorflow;
 namespace mpms = mediapipe::mediasequence;
 
+constexpr char kImageFrameRateTag[] = "IMAGE_FRAME_RATE";
+constexpr char kEncodedMediaStartTimestampTag[] =
+    "ENCODED_MEDIA_START_TIMESTAMP";
+constexpr char kEncodedMediaTag[] = "ENCODED_MEDIA";
+constexpr char kResamplerOptionsTag[] = "RESAMPLER_OPTIONS";
+constexpr char kSandboxedDecoderOptionsTag[] = "SANDBOXED_DECODER_OPTIONS";
+constexpr char kDecoderOptionsTag[] = "DECODER_OPTIONS";
+constexpr char kAudioDecoderOptionsTag[] = "AUDIO_DECODER_OPTIONS";
+constexpr char kDataPathTag[] = "DATA_PATH";
+constexpr char kDatasetRootTag[] = "DATASET_ROOT";
+constexpr char kMediaIdTag[] = "MEDIA_ID";
+constexpr char kFloatFeatureFdenseMaxTag[] = "FLOAT_FEATURE_FDENSE_MAX";
+constexpr char kFloatFeatureFdenseAvgTag[] = "FLOAT_FEATURE_FDENSE_AVG";
+constexpr char kAudioOtherTag[] = "AUDIO_OTHER";
+constexpr char kAudioTestTag[] = "AUDIO_TEST";
+constexpr char kFloatFeatureOtherTag[] = "FLOAT_FEATURE_OTHER";
+constexpr char kFloatFeatureTestTag[] = "FLOAT_FEATURE_TEST";
+constexpr char kBboxPrefixTag[] = "BBOX_PREFIX";
+constexpr char kKeypointsTag[] = "KEYPOINTS";
+constexpr char kBboxTag[] = "BBOX";
+constexpr char kForwardFlowEncodedTag[] = "FORWARD_FLOW_ENCODED";
+constexpr char kImagePrefixTag[] = "IMAGE_PREFIX";
+constexpr char kImageTag[] = "IMAGE";
+constexpr char kSequenceExampleTag[] = "SEQUENCE_EXAMPLE";
+
 class UnpackMediaSequenceCalculatorTest : public ::testing::Test {
  protected:
   void SetUpCalculator(const std::vector<std::string>& output_streams,
@@ -95,13 +120,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksOneImage) {
     mpms::AddImageEncoded(test_image_string, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("IMAGE").packets;
+      runner_->Outputs().Tag(kImageTag).packets;
   ASSERT_EQ(num_images, output_packets.size());
 
   for (int i = 0; i < num_images; ++i) {
@@ -124,13 +149,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksTwoImages) {
     mpms::AddImageEncoded(test_image_string, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("IMAGE").packets;
+      runner_->Outputs().Tag(kImageTag).packets;
   ASSERT_EQ(num_images, output_packets.size());
 
   for (int i = 0; i < num_images; ++i) {
@@ -154,13 +179,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksTwoPrefixedImages) {
     mpms::AddImageEncoded(prefix, test_image_string, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("IMAGE_PREFIX").packets;
+      runner_->Outputs().Tag(kImagePrefixTag).packets;
   ASSERT_EQ(num_images, output_packets.size());
 
   for (int i = 0; i < num_images; ++i) {
@@ -182,12 +207,12 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksOneForwardFlowImage) {
     mpms::AddForwardFlowEncoded(test_image_string, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("FORWARD_FLOW_ENCODED").packets;
+      runner_->Outputs().Tag(kForwardFlowEncodedTag).packets;
   ASSERT_EQ(num_forward_flow_images, output_packets.size());
 
   for (int i = 0; i < num_forward_flow_images; ++i) {
@@ -211,12 +236,12 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksTwoForwardFlowImages) {
     mpms::AddForwardFlowEncoded(test_image_strings[i], input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("FORWARD_FLOW_ENCODED").packets;
+      runner_->Outputs().Tag(kForwardFlowEncodedTag).packets;
   ASSERT_EQ(num_forward_flow_images, output_packets.size());
 
   for (int i = 0; i < num_forward_flow_images; ++i) {
@@ -240,13 +265,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksBBoxes) {
     mpms::AddBBoxTimestamp(i, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("BBOX").packets;
+      runner_->Outputs().Tag(kBboxTag).packets;
   ASSERT_EQ(bboxes.size(), output_packets.size());
 
   for (int i = 0; i < bboxes.size(); ++i) {
@@ -274,13 +299,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksPrefixedBBoxes) {
     mpms::AddBBoxTimestamp(prefix, i, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("BBOX_PREFIX").packets;
+      runner_->Outputs().Tag(kBboxPrefixTag).packets;
   ASSERT_EQ(bboxes.size(), output_packets.size());
 
   for (int i = 0; i < bboxes.size(); ++i) {
@@ -306,13 +331,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksTwoFloatLists) {
     mpms::AddFeatureTimestamp("OTHER", i, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("FLOAT_FEATURE_TEST").packets;
+      runner_->Outputs().Tag(kFloatFeatureTestTag).packets;
   ASSERT_EQ(num_float_lists, output_packets.size());
 
   for (int i = 0; i < num_float_lists; ++i) {
@@ -322,7 +347,7 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksTwoFloatLists) {
   }
 
   const std::vector<Packet>& output_packets_other =
-      runner_->Outputs().Tag("FLOAT_FEATURE_OTHER").packets;
+      runner_->Outputs().Tag(kFloatFeatureOtherTag).packets;
   ASSERT_EQ(num_float_lists, output_packets_other.size());
 
   for (int i = 0; i < num_float_lists; ++i) {
@@ -352,12 +377,12 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksNonOverlappingTimestamps) {
     mpms::AddFeatureTimestamp("OTHER", i + 5, input_sequence.get());
   }
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("IMAGE").packets;
+      runner_->Outputs().Tag(kImageTag).packets;
   ASSERT_EQ(num_images, output_packets.size());
 
   for (int i = 0; i < num_images; ++i) {
@@ -366,7 +391,7 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksNonOverlappingTimestamps) {
   }
 
   const std::vector<Packet>& output_packets_other =
-      runner_->Outputs().Tag("FLOAT_FEATURE_OTHER").packets;
+      runner_->Outputs().Tag(kFloatFeatureOtherTag).packets;
   ASSERT_EQ(num_float_lists, output_packets_other.size());
 
   for (int i = 0; i < num_float_lists; ++i) {
@@ -389,12 +414,12 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksTwoPostStreamFloatLists) {
   mpms::AddFeatureTimestamp("FDENSE_MAX", Timestamp::PostStream().Value(),
                             input_sequence.get());
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& fdense_avg_packets =
-      runner_->Outputs().Tag("FLOAT_FEATURE_FDENSE_AVG").packets;
+      runner_->Outputs().Tag(kFloatFeatureFdenseAvgTag).packets;
   ASSERT_EQ(fdense_avg_packets.size(), 1);
   const auto& fdense_avg_vector =
       fdense_avg_packets[0].Get<std::vector<float>>();
@@ -403,7 +428,7 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksTwoPostStreamFloatLists) {
               ::testing::Eq(Timestamp::PostStream()));
 
   const std::vector<Packet>& fdense_max_packets =
-      runner_->Outputs().Tag("FLOAT_FEATURE_FDENSE_MAX").packets;
+      runner_->Outputs().Tag(kFloatFeatureFdenseMaxTag).packets;
   ASSERT_EQ(fdense_max_packets.size(), 1);
   const auto& fdense_max_vector =
       fdense_max_packets[0].Get<std::vector<float>>();
@@ -430,13 +455,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksImageWithPostStreamFloatList) {
   mpms::AddFeatureTimestamp("FDENSE_MAX", Timestamp::PostStream().Value(),
                             input_sequence.get());
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("IMAGE").packets;
+      runner_->Outputs().Tag(kImageTag).packets;
   ASSERT_EQ(num_images, output_packets.size());
 
   for (int i = 0; i < num_images; ++i) {
@@ -463,13 +488,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksPostStreamFloatListWithImage) {
   mpms::AddFeatureTimestamp("FDENSE_MAX", Timestamp::PostStream().Value(),
                             input_sequence.get());
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(input_sequence.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   const std::vector<Packet>& fdense_max_packets =
-      runner_->Outputs().Tag("FLOAT_FEATURE_FDENSE_MAX").packets;
+      runner_->Outputs().Tag(kFloatFeatureFdenseMaxTag).packets;
   ASSERT_EQ(fdense_max_packets.size(), 1);
   const auto& fdense_max_vector =
       fdense_max_packets[0].Get<std::vector<float>>();
@@ -481,17 +506,17 @@ TEST_F(UnpackMediaSequenceCalculatorTest, UnpacksPostStreamFloatListWithImage) {
 TEST_F(UnpackMediaSequenceCalculatorTest, GetDatasetFromPacket) {
   SetUpCalculator({}, {"DATA_PATH:data_path"}, {"DATASET_ROOT:root"});
 
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(sequence_.release());
 
   std::string root = "test_root";
-  runner_->MutableSidePackets()->Tag("DATASET_ROOT") = PointToForeign(&root);
+  runner_->MutableSidePackets()->Tag(kDatasetRootTag) = PointToForeign(&root);
   MP_ASSERT_OK(runner_->Run());
 
   MP_ASSERT_OK(runner_->OutputSidePackets()
-                   .Tag("DATA_PATH")
+                   .Tag(kDataPathTag)
                    .ValidateAsType<std::string>());
-  ASSERT_EQ(runner_->OutputSidePackets().Tag("DATA_PATH").Get<std::string>(),
+  ASSERT_EQ(runner_->OutputSidePackets().Tag(kDataPathTag).Get<std::string>(),
             root + "/" + data_path_);
 }
 
@@ -501,28 +526,28 @@ TEST_F(UnpackMediaSequenceCalculatorTest, GetDatasetFromOptions) {
   options.MutableExtension(UnpackMediaSequenceCalculatorOptions::ext)
       ->set_dataset_root_directory(root);
   SetUpCalculator({}, {"DATA_PATH:data_path"}, {}, &options);
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(sequence_.release());
 
   MP_ASSERT_OK(runner_->Run());
 
   MP_ASSERT_OK(runner_->OutputSidePackets()
-                   .Tag("DATA_PATH")
+                   .Tag(kDataPathTag)
                    .ValidateAsType<std::string>());
-  ASSERT_EQ(runner_->OutputSidePackets().Tag("DATA_PATH").Get<std::string>(),
+  ASSERT_EQ(runner_->OutputSidePackets().Tag(kDataPathTag).Get<std::string>(),
             root + "/" + data_path_);
 }
 
 TEST_F(UnpackMediaSequenceCalculatorTest, GetDatasetFromExample) {
   SetUpCalculator({}, {"DATA_PATH:data_path"});
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(sequence_.release());
   MP_ASSERT_OK(runner_->Run());
 
   MP_ASSERT_OK(runner_->OutputSidePackets()
-                   .Tag("DATA_PATH")
+                   .Tag(kDataPathTag)
                    .ValidateAsType<std::string>());
-  ASSERT_EQ(runner_->OutputSidePackets().Tag("DATA_PATH").Get<std::string>(),
+  ASSERT_EQ(runner_->OutputSidePackets().Tag(kDataPathTag).Get<std::string>(),
             data_path_);
 }
 
@@ -534,20 +559,20 @@ TEST_F(UnpackMediaSequenceCalculatorTest, GetAudioDecoderOptions) {
       ->set_padding_after_label(2);
   SetUpCalculator({}, {"AUDIO_DECODER_OPTIONS:audio_decoder_options"}, {},
                   &options);
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(sequence_.release());
   MP_ASSERT_OK(runner_->Run());
 
   MP_EXPECT_OK(runner_->OutputSidePackets()
-                   .Tag("AUDIO_DECODER_OPTIONS")
+                   .Tag(kAudioDecoderOptionsTag)
                    .ValidateAsType<AudioDecoderOptions>());
   EXPECT_NEAR(runner_->OutputSidePackets()
-                  .Tag("AUDIO_DECODER_OPTIONS")
+                  .Tag(kAudioDecoderOptionsTag)
                   .Get<AudioDecoderOptions>()
                   .start_time(),
               2.0, 1e-5);
   EXPECT_NEAR(runner_->OutputSidePackets()
-                  .Tag("AUDIO_DECODER_OPTIONS")
+                  .Tag(kAudioDecoderOptionsTag)
                   .Get<AudioDecoderOptions>()
                   .end_time(),
               7.0, 1e-5);
@@ -563,20 +588,20 @@ TEST_F(UnpackMediaSequenceCalculatorTest, GetAudioDecoderOptionsOverride) {
       ->set_force_decoding_from_start_of_media(true);
   SetUpCalculator({}, {"AUDIO_DECODER_OPTIONS:audio_decoder_options"}, {},
                   &options);
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(sequence_.release());
   MP_ASSERT_OK(runner_->Run());
 
   MP_EXPECT_OK(runner_->OutputSidePackets()
-                   .Tag("AUDIO_DECODER_OPTIONS")
+                   .Tag(kAudioDecoderOptionsTag)
                    .ValidateAsType<AudioDecoderOptions>());
   EXPECT_NEAR(runner_->OutputSidePackets()
-                  .Tag("AUDIO_DECODER_OPTIONS")
+                  .Tag(kAudioDecoderOptionsTag)
                   .Get<AudioDecoderOptions>()
                   .start_time(),
               0.0, 1e-5);
   EXPECT_NEAR(runner_->OutputSidePackets()
-                  .Tag("AUDIO_DECODER_OPTIONS")
+                  .Tag(kAudioDecoderOptionsTag)
                   .Get<AudioDecoderOptions>()
                   .end_time(),
               7.0, 1e-5);
@@ -594,27 +619,27 @@ TEST_F(UnpackMediaSequenceCalculatorTest, GetPacketResamplingOptions) {
       ->mutable_base_packet_resampler_options()
       ->set_frame_rate(1.0);
   SetUpCalculator({}, {"RESAMPLER_OPTIONS:resampler_options"}, {}, &options);
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(sequence_.release());
   MP_ASSERT_OK(runner_->Run());
 
   MP_EXPECT_OK(runner_->OutputSidePackets()
-                   .Tag("RESAMPLER_OPTIONS")
+                   .Tag(kResamplerOptionsTag)
                    .ValidateAsType<CalculatorOptions>());
   EXPECT_NEAR(runner_->OutputSidePackets()
-                  .Tag("RESAMPLER_OPTIONS")
+                  .Tag(kResamplerOptionsTag)
                   .Get<CalculatorOptions>()
                   .GetExtension(PacketResamplerCalculatorOptions::ext)
                   .start_time(),
               2000000, 1);
   EXPECT_NEAR(runner_->OutputSidePackets()
-                  .Tag("RESAMPLER_OPTIONS")
+                  .Tag(kResamplerOptionsTag)
                   .Get<CalculatorOptions>()
                   .GetExtension(PacketResamplerCalculatorOptions::ext)
                   .end_time(),
               7000000, 1);
   EXPECT_NEAR(runner_->OutputSidePackets()
-                  .Tag("RESAMPLER_OPTIONS")
+                  .Tag(kResamplerOptionsTag)
                   .Get<CalculatorOptions>()
                   .GetExtension(PacketResamplerCalculatorOptions::ext)
                   .frame_rate(),
@@ -623,13 +648,13 @@ TEST_F(UnpackMediaSequenceCalculatorTest, GetPacketResamplingOptions) {
 
 TEST_F(UnpackMediaSequenceCalculatorTest, GetFrameRateFromExample) {
   SetUpCalculator({}, {"IMAGE_FRAME_RATE:frame_rate"});
-  runner_->MutableSidePackets()->Tag("SEQUENCE_EXAMPLE") =
+  runner_->MutableSidePackets()->Tag(kSequenceExampleTag) =
       Adopt(sequence_.release());
   MP_ASSERT_OK(runner_->Run());
   MP_EXPECT_OK(runner_->OutputSidePackets()
-                   .Tag("IMAGE_FRAME_RATE")
+                   .Tag(kImageFrameRateTag)
                    .ValidateAsType<double>());
-  EXPECT_EQ(runner_->OutputSidePackets().Tag("IMAGE_FRAME_RATE").Get<double>(),
+  EXPECT_EQ(runner_->OutputSidePackets().Tag(kImageFrameRateTag).Get<double>(),
             image_frame_rate_);
 }
 

mediapipe/calculators/tensorflow/vector_int_to_tensor_calculator_test.cc

@@ -26,6 +26,10 @@ namespace {
 
 namespace tf = ::tensorflow;
 
+constexpr char kSingleIntTag[] = "SINGLE_INT";
+constexpr char kTensorOutTag[] = "TENSOR_OUT";
+constexpr char kVectorIntTag[] = "VECTOR_INT";
+
 class VectorIntToTensorCalculatorTest : public ::testing::Test {
  protected:
   void SetUpRunner(
@@ -61,13 +65,13 @@ class VectorIntToTensorCalculatorTest : public ::testing::Test {
 
     const int64 time = 1234;
     runner_->MutableInputs()
-        ->Tag("VECTOR_INT")
+        ->Tag(kVectorIntTag)
         .packets.push_back(Adopt(input.release()).At(Timestamp(time)));
 
     EXPECT_TRUE(runner_->Run().ok());
 
     const std::vector<Packet>& output_packets =
-        runner_->Outputs().Tag("TENSOR_OUT").packets;
+        runner_->Outputs().Tag(kTensorOutTag).packets;
     EXPECT_EQ(1, output_packets.size());
     EXPECT_EQ(time, output_packets[0].Timestamp().Value());
     const tf::Tensor& output_tensor = output_packets[0].Get<tf::Tensor>();
@@ -95,13 +99,13 @@ TEST_F(VectorIntToTensorCalculatorTest, TestSingleValue) {
               tensorflow::DT_INT32, false, true);
   const int64 time = 1234;
   runner_->MutableInputs()
-      ->Tag("SINGLE_INT")
+      ->Tag(kSingleIntTag)
       .packets.push_back(MakePacket<int>(1).At(Timestamp(time)));
 
   EXPECT_TRUE(runner_->Run().ok());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("TENSOR_OUT").packets;
+      runner_->Outputs().Tag(kTensorOutTag).packets;
   EXPECT_EQ(1, output_packets.size());
   EXPECT_EQ(time, output_packets[0].Timestamp().Value());
   const tf::Tensor& output_tensor = output_packets[0].Get<tf::Tensor>();
@@ -121,13 +125,13 @@ TEST_F(VectorIntToTensorCalculatorTest, TesOneDim) {
   }
   const int64 time = 1234;
   runner_->MutableInputs()
-      ->Tag("VECTOR_INT")
+      ->Tag(kVectorIntTag)
       .packets.push_back(Adopt(input.release()).At(Timestamp(time)));
 
   EXPECT_TRUE(runner_->Run().ok());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("TENSOR_OUT").packets;
+      runner_->Outputs().Tag(kTensorOutTag).packets;
   EXPECT_EQ(1, output_packets.size());
   EXPECT_EQ(time, output_packets[0].Timestamp().Value());
   const tf::Tensor& output_tensor = output_packets[0].Get<tf::Tensor>();
@@ -152,13 +156,13 @@ TEST_F(VectorIntToTensorCalculatorTest, TestInt64) {
               tensorflow::DT_INT64, false, true);
   const int64 time = 1234;
   runner_->MutableInputs()
-      ->Tag("SINGLE_INT")
+      ->Tag(kSingleIntTag)
       .packets.push_back(MakePacket<int>(1LL << 31).At(Timestamp(time)));
 
   EXPECT_TRUE(runner_->Run().ok());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("TENSOR_OUT").packets;
+      runner_->Outputs().Tag(kTensorOutTag).packets;
   EXPECT_EQ(1, output_packets.size());
   EXPECT_EQ(time, output_packets[0].Timestamp().Value());
   const tf::Tensor& output_tensor = output_packets[0].Get<tf::Tensor>();
@@ -179,13 +183,13 @@ TEST_F(VectorIntToTensorCalculatorTest, TestUint8) {
   }
   const int64 time = 1234;
   runner_->MutableInputs()
-      ->Tag("VECTOR_INT")
+      ->Tag(kVectorIntTag)
       .packets.push_back(Adopt(input.release()).At(Timestamp(time)));
 
   EXPECT_TRUE(runner_->Run().ok());
 
   const std::vector<Packet>& output_packets =
-      runner_->Outputs().Tag("TENSOR_OUT").packets;
+      runner_->Outputs().Tag(kTensorOutTag).packets;
   EXPECT_EQ(1, output_packets.size());
   EXPECT_EQ(time, output_packets[0].Timestamp().Value());
   const tf::Tensor& output_tensor = output_packets[0].Get<tf::Tensor>();

mediapipe/calculators/tflite/tflite_tensors_to_floats_calculator.cc

@@ -18,6 +18,10 @@
 
 namespace mediapipe {
 
+constexpr char kFloatsTag[] = "FLOATS";
+constexpr char kFloatTag[] = "FLOAT";
+constexpr char kTensorsTag[] = "TENSORS";
+
 // A calculator for converting TFLite tensors to to a float or a float vector.
 //
 // Input:
@@ -48,15 +52,16 @@ REGISTER_CALCULATOR(TfLiteTensorsToFloatsCalculator);
 
 absl::Status TfLiteTensorsToFloatsCalculator::GetContract(
     CalculatorContract* cc) {
-  RET_CHECK(cc->Inputs().HasTag("TENSORS"));
+  RET_CHECK(cc->Inputs().HasTag(kTensorsTag));
-  RET_CHECK(cc->Outputs().HasTag("FLOATS") || cc->Outputs().HasTag("FLOAT"));
+  RET_CHECK(cc->Outputs().HasTag(kFloatsTag) ||
+            cc->Outputs().HasTag(kFloatTag));
 
-  cc->Inputs().Tag("TENSORS").Set<std::vector<TfLiteTensor>>();
+  cc->Inputs().Tag(kTensorsTag).Set<std::vector<TfLiteTensor>>();
-  if (cc->Outputs().HasTag("FLOATS")) {
+  if (cc->Outputs().HasTag(kFloatsTag)) {
-    cc->Outputs().Tag("FLOATS").Set<std::vector<float>>();
+    cc->Outputs().Tag(kFloatsTag).Set<std::vector<float>>();
   }
-  if (cc->Outputs().HasTag("FLOAT")) {
+  if (cc->Outputs().HasTag(kFloatTag)) {
-    cc->Outputs().Tag("FLOAT").Set<float>();
+    cc->Outputs().Tag(kFloatTag).Set<float>();
   }
 
   return absl::OkStatus();
@@ -69,10 +74,10 @@ absl::Status TfLiteTensorsToFloatsCalculator::Open(CalculatorContext* cc) {
 }
 
 absl::Status TfLiteTensorsToFloatsCalculator::Process(CalculatorContext* cc) {
-  RET_CHECK(!cc->Inputs().Tag("TENSORS").IsEmpty());
+  RET_CHECK(!cc->Inputs().Tag(kTensorsTag).IsEmpty());
 
   const auto& input_tensors =
-      cc->Inputs().Tag("TENSORS").Get<std::vector<TfLiteTensor>>();
+      cc->Inputs().Tag(kTensorsTag).Get<std::vector<TfLiteTensor>>();
   // TODO: Add option to specify which tensor to take from.
   const TfLiteTensor* raw_tensor = &input_tensors[0];
   const float* raw_floats = raw_tensor->data.f;
@@ -82,18 +87,19 @@ absl::Status TfLiteTensorsToFloatsCalculator::Process(CalculatorContext* cc) {
     num_values *= raw_tensor->dims->data[i];
   }
 
-  if (cc->Outputs().HasTag("FLOAT")) {
+  if (cc->Outputs().HasTag(kFloatTag)) {
     // TODO: Could add an index in the option to specifiy returning one
     // value of a float array.
     RET_CHECK_EQ(num_values, 1);
-    cc->Outputs().Tag("FLOAT").AddPacket(
+    cc->Outputs().Tag(kFloatTag).AddPacket(
         MakePacket<float>(raw_floats[0]).At(cc->InputTimestamp()));
   }
-  if (cc->Outputs().HasTag("FLOATS")) {
+  if (cc->Outputs().HasTag(kFloatsTag)) {
     auto output_floats = absl::make_unique<std::vector<float>>(
         raw_floats, raw_floats + num_values);
-    cc->Outputs().Tag("FLOATS").Add(output_floats.release(),
+    cc->Outputs()
-                                    cc->InputTimestamp());
+        .Tag(kFloatsTag)
+        .Add(output_floats.release(), cc->InputTimestamp());
   }
 
   return absl::OkStatus();

mediapipe/calculators/util/clock_timestamp_calculator.cc

@@ -87,7 +87,7 @@ absl::Status ClockTimestampCalculator::Open(CalculatorContext* cc) {
   // Initialize the clock.
   if (cc->InputSidePackets().HasTag(kClockTag)) {
     clock_ = cc->InputSidePackets()
-                 .Tag("CLOCK")
+                 .Tag(kClockTag)
                  .Get<std::shared_ptr<::mediapipe::Clock>>();
   } else {
     clock_.reset(

mediapipe/calculators/util/collection_has_min_size_calculator_test.cc

@@ -27,6 +27,8 @@
 
 namespace mediapipe {
 
+constexpr char kIterableTag[] = "ITERABLE";
+
 typedef CollectionHasMinSizeCalculator<std::vector<int>>
     TestIntCollectionHasMinSizeCalculator;
 REGISTER_CALCULATOR(TestIntCollectionHasMinSizeCalculator);
@@ -34,7 +36,7 @@ REGISTER_CALCULATOR(TestIntCollectionHasMinSizeCalculator);
 void AddInputVector(const std::vector<int>& input, int64 timestamp,
                     CalculatorRunner* runner) {
   runner->MutableInputs()
-      ->Tag("ITERABLE")
+      ->Tag(kIterableTag)
       .packets.push_back(
           MakePacket<std::vector<int>>(input).At(Timestamp(timestamp)));
 }

mediapipe/calculators/util/detection_letterbox_removal_calculator.cc

@@ -144,7 +144,7 @@ class DetectionLetterboxRemovalCalculator : public CalculatorBase {
     }
 
     cc->Outputs()
-        .Tag("DETECTIONS")
+        .Tag(kDetectionsTag)
         .Add(output_detections.release(), cc->InputTimestamp());
     return absl::OkStatus();
   }

mediapipe/calculators/util/detection_letterbox_removal_calculator_test.cc

@@ -25,6 +25,9 @@
 
 namespace mediapipe {
 
+constexpr char kLetterboxPaddingTag[] = "LETTERBOX_PADDING";
+constexpr char kDetectionsTag[] = "DETECTIONS";
+
 LocationData CreateRelativeLocationData(double xmin, double ymin, double width,
                                         double height) {
   LocationData location_data;
@@ -76,19 +79,19 @@ TEST(DetectionLetterboxRemovalCalculatorTest, PaddingLeftRight) {
   detections->push_back(
       CreateDetection({label}, {}, {0.3f}, location_data, "feature_tag"));
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   auto padding = absl::make_unique<std::array<float, 4>>(
       std::array<float, 4>{0.2f, 0.f, 0.3f, 0.f});
   runner.MutableInputs()
-      ->Tag("LETTERBOX_PADDING")
+      ->Tag(kLetterboxPaddingTag)
       .packets.push_back(Adopt(padding.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& output =
-      runner.Outputs().Tag("DETECTIONS").packets;
+      runner.Outputs().Tag(kDetectionsTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& output_detections = output[0].Get<std::vector<Detection>>();
 
@@ -124,19 +127,19 @@ TEST(DetectionLetterboxRemovalCalculatorTest, PaddingTopBottom) {
   detections->push_back(
       CreateDetection({label}, {}, {0.3f}, location_data, "feature_tag"));
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   auto padding = absl::make_unique<std::array<float, 4>>(
       std::array<float, 4>{0.f, 0.2f, 0.f, 0.3f});
   runner.MutableInputs()
-      ->Tag("LETTERBOX_PADDING")
+      ->Tag(kLetterboxPaddingTag)
       .packets.push_back(Adopt(padding.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& output =
-      runner.Outputs().Tag("DETECTIONS").packets;
+      runner.Outputs().Tag(kDetectionsTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& output_detections = output[0].Get<std::vector<Detection>>();
 

mediapipe/calculators/util/detection_projection_calculator_test.cc

@@ -31,6 +31,9 @@
 namespace mediapipe {
 namespace {
 
+constexpr char kProjectionMatrixTag[] = "PROJECTION_MATRIX";
+constexpr char kDetectionsTag[] = "DETECTIONS";
+
 using ::testing::ElementsAre;
 using ::testing::FloatNear;
 
@@ -74,19 +77,19 @@ absl::StatusOr<Detection> RunProjectionCalculator(
   )pb"));
 
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(MakePacket<std::vector<Detection>>(
                              std::vector<Detection>({std::move(detection)}))
                              .At(Timestamp::PostStream()));
   runner.MutableInputs()
-      ->Tag("PROJECTION_MATRIX")
+      ->Tag(kProjectionMatrixTag)
       .packets.push_back(
           MakePacket<std::array<float, 16>>(std::move(project_mat))
               .At(Timestamp::PostStream()));
 
   MP_RETURN_IF_ERROR(runner.Run());
   const std::vector<Packet>& output =
-      runner.Outputs().Tag("DETECTIONS").packets;
+      runner.Outputs().Tag(kDetectionsTag).packets;
   RET_CHECK_EQ(output.size(), 1);
   const auto& output_detections = output[0].Get<std::vector<Detection>>();
 

mediapipe/calculators/util/detections_to_rects_calculator_test.cc

@@ -32,6 +32,14 @@
 namespace mediapipe {
 namespace {
 
+constexpr char kNormRectsTag[] = "NORM_RECTS";
+constexpr char kRectsTag[] = "RECTS";
+constexpr char kDetectionsTag[] = "DETECTIONS";
+constexpr char kNormRectTag[] = "NORM_RECT";
+constexpr char kImageSizeTag[] = "IMAGE_SIZE";
+constexpr char kRectTag[] = "RECT";
+constexpr char kDetectionTag[] = "DETECTION";
+
 MATCHER_P4(RectEq, x_center, y_center, width, height, "") {
   return testing::Value(arg.x_center(), testing::Eq(x_center)) &&
          testing::Value(arg.y_center(), testing::Eq(y_center)) &&
@@ -94,12 +102,12 @@ TEST(DetectionsToRectsCalculatorTest, DetectionToRect) {
       DetectionWithLocationData(100, 200, 300, 400));
 
   runner.MutableInputs()
-      ->Tag("DETECTION")
+      ->Tag(kDetectionTag)
       .packets.push_back(
           Adopt(detection.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
-  const std::vector<Packet>& output = runner.Outputs().Tag("RECT").packets;
+  const std::vector<Packet>& output = runner.Outputs().Tag(kRectTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& rect = output[0].Get<Rect>();
   EXPECT_THAT(rect, RectEq(250, 400, 300, 400));
@@ -120,16 +128,16 @@ absl::StatusOr<Rect> RunDetectionKeyPointsToRectCalculation(
   )pb"));
 
   runner.MutableInputs()
-      ->Tag("DETECTION")
+      ->Tag(kDetectionTag)
       .packets.push_back(MakePacket<Detection>(std::move(detection))
                              .At(Timestamp::PostStream()));
   runner.MutableInputs()
-      ->Tag("IMAGE_SIZE")
+      ->Tag(kImageSizeTag)
       .packets.push_back(MakePacket<std::pair<int, int>>(image_size)
                              .At(Timestamp::PostStream()));
 
   MP_RETURN_IF_ERROR(runner.Run());
-  const std::vector<Packet>& output = runner.Outputs().Tag("RECT").packets;
+  const std::vector<Packet>& output = runner.Outputs().Tag(kRectTag).packets;
   RET_CHECK_EQ(output.size(), 1);
   return output[0].Get<Rect>();
 }
@@ -176,12 +184,13 @@ TEST(DetectionsToRectsCalculatorTest, DetectionToNormalizedRect) {
       DetectionWithRelativeLocationData(0.1, 0.2, 0.3, 0.4));
 
   runner.MutableInputs()
-      ->Tag("DETECTION")
+      ->Tag(kDetectionTag)
       .packets.push_back(
           Adopt(detection.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
-  const std::vector<Packet>& output = runner.Outputs().Tag("NORM_RECT").packets;
+  const std::vector<Packet>& output =
+      runner.Outputs().Tag(kNormRectTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& rect = output[0].Get<NormalizedRect>();
   EXPECT_THAT(rect, NormRectEq(0.25f, 0.4f, 0.3f, 0.4f));
@@ -201,12 +210,13 @@ absl::StatusOr<NormalizedRect> RunDetectionKeyPointsToNormRectCalculation(
   )pb"));
 
   runner.MutableInputs()
-      ->Tag("DETECTION")
+      ->Tag(kDetectionTag)
       .packets.push_back(MakePacket<Detection>(std::move(detection))
                              .At(Timestamp::PostStream()));
 
   MP_RETURN_IF_ERROR(runner.Run());
-  const std::vector<Packet>& output = runner.Outputs().Tag("NORM_RECT").packets;
+  const std::vector<Packet>& output =
+      runner.Outputs().Tag(kNormRectTag).packets;
   RET_CHECK_EQ(output.size(), 1);
   return output[0].Get<NormalizedRect>();
 }
@@ -248,12 +258,12 @@ TEST(DetectionsToRectsCalculatorTest, DetectionsToRect) {
   detections->push_back(DetectionWithLocationData(200, 300, 400, 500));
 
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
-  const std::vector<Packet>& output = runner.Outputs().Tag("RECT").packets;
+  const std::vector<Packet>& output = runner.Outputs().Tag(kRectTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& rect = output[0].Get<Rect>();
   EXPECT_THAT(rect, RectEq(250, 400, 300, 400));
@@ -271,12 +281,13 @@ TEST(DetectionsToRectsCalculatorTest, DetectionsToNormalizedRect) {
   detections->push_back(DetectionWithRelativeLocationData(0.2, 0.3, 0.4, 0.5));
 
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
-  const std::vector<Packet>& output = runner.Outputs().Tag("NORM_RECT").packets;
+  const std::vector<Packet>& output =
+      runner.Outputs().Tag(kNormRectTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& rect = output[0].Get<NormalizedRect>();
   EXPECT_THAT(rect, NormRectEq(0.25f, 0.4f, 0.3f, 0.4f));
@@ -294,12 +305,12 @@ TEST(DetectionsToRectsCalculatorTest, DetectionsToRects) {
   detections->push_back(DetectionWithLocationData(200, 300, 400, 500));
 
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
-  const std::vector<Packet>& output = runner.Outputs().Tag("RECTS").packets;
+  const std::vector<Packet>& output = runner.Outputs().Tag(kRectsTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& rects = output[0].Get<std::vector<Rect>>();
   ASSERT_EQ(rects.size(), 2);
@@ -319,13 +330,13 @@ TEST(DetectionsToRectsCalculatorTest, DetectionsToNormalizedRects) {
   detections->push_back(DetectionWithRelativeLocationData(0.2, 0.3, 0.4, 0.5));
 
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& output =
-      runner.Outputs().Tag("NORM_RECTS").packets;
+      runner.Outputs().Tag(kNormRectsTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& rects = output[0].Get<std::vector<NormalizedRect>>();
   ASSERT_EQ(rects.size(), 2);
@@ -344,12 +355,12 @@ TEST(DetectionsToRectsCalculatorTest, DetectionToRects) {
       DetectionWithLocationData(100, 200, 300, 400));
 
   runner.MutableInputs()
-      ->Tag("DETECTION")
+      ->Tag(kDetectionTag)
       .packets.push_back(
           Adopt(detection.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
-  const std::vector<Packet>& output = runner.Outputs().Tag("RECTS").packets;
+  const std::vector<Packet>& output = runner.Outputs().Tag(kRectsTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& rects = output[0].Get<std::vector<Rect>>();
   EXPECT_EQ(rects.size(), 1);
@@ -367,13 +378,13 @@ TEST(DetectionsToRectsCalculatorTest, DetectionToNormalizedRects) {
       DetectionWithRelativeLocationData(0.1, 0.2, 0.3, 0.4));
 
   runner.MutableInputs()
-      ->Tag("DETECTION")
+      ->Tag(kDetectionTag)
       .packets.push_back(
           Adopt(detection.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& output =
-      runner.Outputs().Tag("NORM_RECTS").packets;
+      runner.Outputs().Tag(kNormRectsTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& rects = output[0].Get<std::vector<NormalizedRect>>();
   ASSERT_EQ(rects.size(), 1);
@@ -391,7 +402,7 @@ TEST(DetectionsToRectsCalculatorTest, WrongInputToRect) {
   detections->push_back(DetectionWithRelativeLocationData(0.1, 0.2, 0.3, 0.4));
 
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
@@ -411,7 +422,7 @@ TEST(DetectionsToRectsCalculatorTest, WrongInputToNormalizedRect) {
   detections->push_back(DetectionWithLocationData(100, 200, 300, 400));
 
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 

mediapipe/calculators/util/detections_to_render_data_calculator_test.cc

@@ -30,6 +30,10 @@
 
 namespace mediapipe {
 
+constexpr char kDetectionsTag[] = "DETECTIONS";
+constexpr char kRenderDataTag[] = "RENDER_DATA";
+constexpr char kDetectionListTag[] = "DETECTION_LIST";
+
 using ::testing::DoubleNear;
 
 // Error tolerance for pixels, distances, etc.
@@ -97,13 +101,13 @@ TEST(DetectionsToRenderDataCalculatorTest, OnlyDetecctionList) {
       CreateDetection({"label1"}, {}, {0.3}, location_data, "feature_tag");
 
   runner.MutableInputs()
-      ->Tag("DETECTION_LIST")
+      ->Tag(kDetectionListTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& output =
-      runner.Outputs().Tag("RENDER_DATA").packets;
+      runner.Outputs().Tag(kRenderDataTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& actual = output[0].Get<RenderData>();
   EXPECT_EQ(actual.render_annotations_size(), 3);
@@ -131,13 +135,13 @@ TEST(DetectionsToRenderDataCalculatorTest, OnlyDetecctionVector) {
       CreateDetection({"label1"}, {}, {0.3}, location_data, "feature_tag"));
 
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& output =
-      runner.Outputs().Tag("RENDER_DATA").packets;
+      runner.Outputs().Tag(kRenderDataTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& actual = output[0].Get<RenderData>();
   EXPECT_EQ(actual.render_annotations_size(), 3);
@@ -165,7 +169,7 @@ TEST(DetectionsToRenderDataCalculatorTest, BothDetecctionListAndVector) {
   *(detection_list->add_detection()) =
       CreateDetection({"label1"}, {}, {0.3}, location_data1, "feature_tag1");
   runner.MutableInputs()
-      ->Tag("DETECTION_LIST")
+      ->Tag(kDetectionListTag)
       .packets.push_back(
           Adopt(detection_list.release()).At(Timestamp::PostStream()));
 
@@ -174,13 +178,13 @@ TEST(DetectionsToRenderDataCalculatorTest, BothDetecctionListAndVector) {
   detections->push_back(
       CreateDetection({"label2"}, {}, {0.6}, location_data2, "feature_tag2"));
   runner.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& actual =
-      runner.Outputs().Tag("RENDER_DATA").packets;
+      runner.Outputs().Tag(kRenderDataTag).packets;
   ASSERT_EQ(1, actual.size());
   // Check the feature tag for item from detection list.
   EXPECT_EQ(
@@ -209,19 +213,19 @@ TEST(DetectionsToRenderDataCalculatorTest, ProduceEmptyPacket) {
 
   auto detection_list1(absl::make_unique<DetectionList>());
   runner1.MutableInputs()
-      ->Tag("DETECTION_LIST")
+      ->Tag(kDetectionListTag)
       .packets.push_back(
           Adopt(detection_list1.release()).At(Timestamp::PostStream()));
 
   auto detections1(absl::make_unique<std::vector<Detection>>());
   runner1.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections1.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner1.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& exact1 =
-      runner1.Outputs().Tag("RENDER_DATA").packets;
+      runner1.Outputs().Tag(kRenderDataTag).packets;
   ASSERT_EQ(0, exact1.size());
 
   // Check when produce_empty_packet is true.
@@ -240,19 +244,19 @@ TEST(DetectionsToRenderDataCalculatorTest, ProduceEmptyPacket) {
 
   auto detection_list2(absl::make_unique<DetectionList>());
   runner2.MutableInputs()
-      ->Tag("DETECTION_LIST")
+      ->Tag(kDetectionListTag)
       .packets.push_back(
           Adopt(detection_list2.release()).At(Timestamp::PostStream()));
 
   auto detections2(absl::make_unique<std::vector<Detection>>());
   runner2.MutableInputs()
-      ->Tag("DETECTIONS")
+      ->Tag(kDetectionsTag)
       .packets.push_back(
           Adopt(detections2.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner2.Run()) << "Calculator execution failed.";
   const std::vector<Packet>& exact2 =
-      runner2.Outputs().Tag("RENDER_DATA").packets;
+      runner2.Outputs().Tag(kRenderDataTag).packets;
   ASSERT_EQ(1, exact2.size());
   EXPECT_EQ(exact2[0].Get<RenderData>().render_annotations_size(), 0);
 }

mediapipe/calculators/util/labels_to_render_data_calculator.cc

@@ -32,6 +32,12 @@
 
 namespace mediapipe {
 
+constexpr char kRenderDataTag[] = "RENDER_DATA";
+constexpr char kVideoPrestreamTag[] = "VIDEO_PRESTREAM";
+constexpr char kScoresTag[] = "SCORES";
+constexpr char kLabelsTag[] = "LABELS";
+constexpr char kClassificationsTag[] = "CLASSIFICATIONS";
+
 constexpr float kFontHeightScale = 1.25f;
 
 // A calculator takes in pairs of labels and scores or classifications, outputs
@@ -74,20 +80,20 @@ class LabelsToRenderDataCalculator : public CalculatorBase {
 REGISTER_CALCULATOR(LabelsToRenderDataCalculator);
 
 absl::Status LabelsToRenderDataCalculator::GetContract(CalculatorContract* cc) {
-  if (cc->Inputs().HasTag("CLASSIFICATIONS")) {
+  if (cc->Inputs().HasTag(kClassificationsTag)) {
-    cc->Inputs().Tag("CLASSIFICATIONS").Set<ClassificationList>();
+    cc->Inputs().Tag(kClassificationsTag).Set<ClassificationList>();
   } else {
-    RET_CHECK(cc->Inputs().HasTag("LABELS"))
+    RET_CHECK(cc->Inputs().HasTag(kLabelsTag))
         << "Must provide input stream \"LABELS\"";
-    cc->Inputs().Tag("LABELS").Set<std::vector<std::string>>();
+    cc->Inputs().Tag(kLabelsTag).Set<std::vector<std::string>>();
-    if (cc->Inputs().HasTag("SCORES")) {
+    if (cc->Inputs().HasTag(kScoresTag)) {
-      cc->Inputs().Tag("SCORES").Set<std::vector<float>>();
+      cc->Inputs().Tag(kScoresTag).Set<std::vector<float>>();
     }
   }
-  if (cc->Inputs().HasTag("VIDEO_PRESTREAM")) {
+  if (cc->Inputs().HasTag(kVideoPrestreamTag)) {
-    cc->Inputs().Tag("VIDEO_PRESTREAM").Set<VideoHeader>();
+    cc->Inputs().Tag(kVideoPrestreamTag).Set<VideoHeader>();
   }
-  cc->Outputs().Tag("RENDER_DATA").Set<RenderData>();
+  cc->Outputs().Tag(kRenderDataTag).Set<RenderData>();
   return absl::OkStatus();
 }
 
@@ -100,10 +106,10 @@ absl::Status LabelsToRenderDataCalculator::Open(CalculatorContext* cc) {
 }
 
 absl::Status LabelsToRenderDataCalculator::Process(CalculatorContext* cc) {
-  if (cc->Inputs().HasTag("VIDEO_PRESTREAM") &&
+  if (cc->Inputs().HasTag(kVideoPrestreamTag) &&
       cc->InputTimestamp() == Timestamp::PreStream()) {
     const VideoHeader& video_header =
-        cc->Inputs().Tag("VIDEO_PRESTREAM").Get<VideoHeader>();
+        cc->Inputs().Tag(kVideoPrestreamTag).Get<VideoHeader>();
     video_width_ = video_header.width;
     video_height_ = video_header.height;
     return absl::OkStatus();
@@ -114,9 +120,9 @@ absl::Status LabelsToRenderDataCalculator::Process(CalculatorContext* cc) {
 
   std::vector<std::string> labels;
   std::vector<float> scores;
-  if (cc->Inputs().HasTag("CLASSIFICATIONS")) {
+  if (cc->Inputs().HasTag(kClassificationsTag)) {
     const ClassificationList& classifications =
-        cc->Inputs().Tag("CLASSIFICATIONS").Get<ClassificationList>();
+        cc->Inputs().Tag(kClassificationsTag).Get<ClassificationList>();
     labels.resize(classifications.classification_size());
     scores.resize(classifications.classification_size());
     for (int i = 0; i < classifications.classification_size(); ++i) {
@@ -129,15 +135,15 @@ absl::Status LabelsToRenderDataCalculator::Process(CalculatorContext* cc) {
     }
   } else {
     const std::vector<std::string>& label_vector =
-        cc->Inputs().Tag("LABELS").Get<std::vector<std::string>>();
+        cc->Inputs().Tag(kLabelsTag).Get<std::vector<std::string>>();
     labels.resize(label_vector.size());
     for (int i = 0; i < label_vector.size(); ++i) {
       labels[i] = label_vector[i];
     }
 
-    if (cc->Inputs().HasTag("SCORES")) {
+    if (cc->Inputs().HasTag(kScoresTag)) {
       std::vector<float> score_vector =
-          cc->Inputs().Tag("SCORES").Get<std::vector<float>>();
+          cc->Inputs().Tag(kScoresTag).Get<std::vector<float>>();
       CHECK_EQ(label_vector.size(), score_vector.size());
       scores.resize(label_vector.size());
       for (int i = 0; i < label_vector.size(); ++i) {
@@ -169,7 +175,7 @@ absl::Status LabelsToRenderDataCalculator::Process(CalculatorContext* cc) {
 
     auto* text = label_annotation->mutable_text();
     std::string display_text = labels[i];
-    if (cc->Inputs().HasTag("SCORES")) {
+    if (cc->Inputs().HasTag(kScoresTag)) {
       absl::StrAppend(&display_text, ":", scores[i]);
     }
     text->set_display_text(display_text);
@@ -179,7 +185,7 @@ absl::Status LabelsToRenderDataCalculator::Process(CalculatorContext* cc) {
     text->set_font_face(options_.font_face());
   }
   cc->Outputs()
-      .Tag("RENDER_DATA")
+      .Tag(kRenderDataTag)
       .AddPacket(MakePacket<RenderData>(render_data).At(cc->InputTimestamp()));
 
   return absl::OkStatus();

mediapipe/calculators/util/landmark_letterbox_removal_calculator_test.cc

@@ -24,6 +24,9 @@
 
 namespace mediapipe {
 
+constexpr char kLetterboxPaddingTag[] = "LETTERBOX_PADDING";
+constexpr char kLandmarksTag[] = "LANDMARKS";
+
 NormalizedLandmark CreateLandmark(float x, float y) {
   NormalizedLandmark landmark;
   landmark.set_x(x);
@@ -48,18 +51,19 @@ TEST(LandmarkLetterboxRemovalCalculatorTest, PaddingLeftRight) {
   *landmarks->add_landmark() = CreateLandmark(0.2f, 0.2f);
   *landmarks->add_landmark() = CreateLandmark(0.7f, 0.7f);
   runner.MutableInputs()
-      ->Tag("LANDMARKS")
+      ->Tag(kLandmarksTag)
       .packets.push_back(
           Adopt(landmarks.release()).At(Timestamp::PostStream()));
 
   auto padding = absl::make_unique<std::array<float, 4>>(
       std::array<float, 4>{0.2f, 0.f, 0.3f, 0.f});
   runner.MutableInputs()
-      ->Tag("LETTERBOX_PADDING")
+      ->Tag(kLetterboxPaddingTag)
       .packets.push_back(Adopt(padding.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
-  const std::vector<Packet>& output = runner.Outputs().Tag("LANDMARKS").packets;
+  const std::vector<Packet>& output =
+      runner.Outputs().Tag(kLandmarksTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& output_landmarks = output[0].Get<NormalizedLandmarkList>();
 
@@ -84,18 +88,19 @@ TEST(LandmarkLetterboxRemovalCalculatorTest, PaddingTopBottom) {
   landmark = landmarks->add_landmark();
   *landmark = CreateLandmark(0.7f, 0.7f);
   runner.MutableInputs()
-      ->Tag("LANDMARKS")
+      ->Tag(kLandmarksTag)
       .packets.push_back(
           Adopt(landmarks.release()).At(Timestamp::PostStream()));
 
   auto padding = absl::make_unique<std::array<float, 4>>(
       std::array<float, 4>{0.0f, 0.2f, 0.0f, 0.3f});
   runner.MutableInputs()
-      ->Tag("LETTERBOX_PADDING")
+      ->Tag(kLetterboxPaddingTag)
       .packets.push_back(Adopt(padding.release()).At(Timestamp::PostStream()));
 
   MP_ASSERT_OK(runner.Run()) << "Calculator execution failed.";
-  const std::vector<Packet>& output = runner.Outputs().Tag("LANDMARKS").packets;
+  const std::vector<Packet>& output =
+      runner.Outputs().Tag(kLandmarksTag).packets;
   ASSERT_EQ(1, output.size());
   const auto& output_landmarks = output[0].Get<NormalizedLandmarkList>();
 

mediapipe/calculators/util/landmark_projection_calculator_test.cc

@@ -16,6 +16,10 @@
 namespace mediapipe {
 namespace {
 
+constexpr char kProjectionMatrixTag[] = "PROJECTION_MATRIX";
+constexpr char kNormRectTag[] = "NORM_RECT";
+constexpr char kNormLandmarksTag[] = "NORM_LANDMARKS";
+
 absl::StatusOr<mediapipe::NormalizedLandmarkList> RunCalculator(
     mediapipe::NormalizedLandmarkList input, mediapipe::NormalizedRect rect) {
   mediapipe::CalculatorRunner runner(
@@ -26,17 +30,17 @@ absl::StatusOr<mediapipe::NormalizedLandmarkList> RunCalculator(
         output_stream: "NORM_LANDMARKS:projected_landmarks"
       )pb"));
   runner.MutableInputs()
-      ->Tag("NORM_LANDMARKS")
+      ->Tag(kNormLandmarksTag)
       .packets.push_back(
           MakePacket<mediapipe::NormalizedLandmarkList>(std::move(input))
               .At(Timestamp(1)));
   runner.MutableInputs()
-      ->Tag("NORM_RECT")
+      ->Tag(kNormRectTag)
       .packets.push_back(MakePacket<mediapipe::NormalizedRect>(std::move(rect))
                              .At(Timestamp(1)));
 
   MP_RETURN_IF_ERROR(runner.Run());
-  const auto& output_packets = runner.Outputs().Tag("NORM_LANDMARKS").packets;
+  const auto& output_packets = runner.Outputs().Tag(kNormLandmarksTag).packets;
   RET_CHECK_EQ(output_packets.size(), 1);
   return output_packets[0].Get<mediapipe::NormalizedLandmarkList>();
 }
@@ -104,17 +108,17 @@ absl::StatusOr<mediapipe::NormalizedLandmarkList> RunCalculator(
         output_stream: "NORM_LANDMARKS:projected_landmarks"
       )pb"));
   runner.MutableInputs()
-      ->Tag("NORM_LANDMARKS")
+      ->Tag(kNormLandmarksTag)
       .packets.push_back(
           MakePacket<mediapipe::NormalizedLandmarkList>(std::move(input))
               .At(Timestamp(1)));
   runner.MutableInputs()
-      ->Tag("PROJECTION_MATRIX")
+      ->Tag(kProjectionMatrixTag)
       .packets.push_back(MakePacket<std::array<float, 16>>(std::move(matrix))
                              .At(Timestamp(1)));
 
   MP_RETURN_IF_ERROR(runner.Run());
-  const auto& output_packets = runner.Outputs().Tag("NORM_LANDMARKS").packets;
+  const auto& output_packets = runner.Outputs().Tag(kNormLandmarksTag).packets;
   RET_CHECK_EQ(output_packets.size(), 1);
   return output_packets[0].Get<mediapipe::NormalizedLandmarkList>();
 }

mediapipe/calculators/util/local_file_pattern_contents_calculator.cc

@@ -20,6 +20,11 @@
 #include "mediapipe/framework/port/status.h"
 
 namespace mediapipe {
+
+constexpr char kContentsTag[] = "CONTENTS";
+constexpr char kFileSuffixTag[] = "FILE_SUFFIX";
+constexpr char kFileDirectoryTag[] = "FILE_DIRECTORY";
+
 // The calculator takes the path to local directory and desired file suffix to
 // mach as input side packets, and outputs the contents of those files that
 // match the pattern. Those matched files will be sent sequentially through the
@@ -35,16 +40,16 @@ namespace mediapipe {
 class LocalFilePatternContentsCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->InputSidePackets().Tag("FILE_DIRECTORY").Set<std::string>();
+    cc->InputSidePackets().Tag(kFileDirectoryTag).Set<std::string>();
-    cc->InputSidePackets().Tag("FILE_SUFFIX").Set<std::string>();
+    cc->InputSidePackets().Tag(kFileSuffixTag).Set<std::string>();
-    cc->Outputs().Tag("CONTENTS").Set<std::string>();
+    cc->Outputs().Tag(kContentsTag).Set<std::string>();
     return absl::OkStatus();
   }
 
   absl::Status Open(CalculatorContext* cc) override {
     MP_RETURN_IF_ERROR(mediapipe::file::MatchFileTypeInDirectory(
-        cc->InputSidePackets().Tag("FILE_DIRECTORY").Get<std::string>(),
+        cc->InputSidePackets().Tag(kFileDirectoryTag).Get<std::string>(),
-        cc->InputSidePackets().Tag("FILE_SUFFIX").Get<std::string>(),
+        cc->InputSidePackets().Tag(kFileSuffixTag).Get<std::string>(),
         &filenames_));
     return absl::OkStatus();
   }
@@ -57,7 +62,7 @@ class LocalFilePatternContentsCalculator : public CalculatorBase {
           filenames_[current_output_], contents.get()));
       ++current_output_;
       cc->Outputs()
-          .Tag("CONTENTS")
+          .Tag(kContentsTag)
           .Add(contents.release(), Timestamp(current_output_));
     } else {
       return tool::StatusStop();

mediapipe/calculators/util/packet_latency_calculator.cc

@@ -217,7 +217,7 @@ absl::Status PacketLatencyCalculator::Open(CalculatorContext* cc) {
   // Initialize the clock.
   if (cc->InputSidePackets().HasTag(kClockTag)) {
     clock_ = cc->InputSidePackets()
-                 .Tag("CLOCK")
+                 .Tag(kClockTag)
                  .Get<std::shared_ptr<::mediapipe::Clock>>();
   } else {
     clock_ = std::shared_ptr<::mediapipe::Clock>(

mediapipe/calculators/util/thresholding_calculator.cc

@@ -17,6 +17,12 @@
 
 namespace mediapipe {
 
+constexpr char kThresholdTag[] = "THRESHOLD";
+constexpr char kRejectTag[] = "REJECT";
+constexpr char kAcceptTag[] = "ACCEPT";
+constexpr char kFlagTag[] = "FLAG";
+constexpr char kFloatTag[] = "FLOAT";
+
 // Applies a threshold on a stream of numeric values and outputs a flag and/or
 // accept/reject stream. The threshold can be specified by one of the following:
 //   1) Input stream.
@@ -61,24 +67,24 @@ class ThresholdingCalculator : public CalculatorBase {
 REGISTER_CALCULATOR(ThresholdingCalculator);
 
 absl::Status ThresholdingCalculator::GetContract(CalculatorContract* cc) {
-  RET_CHECK(cc->Inputs().HasTag("FLOAT"));
+  RET_CHECK(cc->Inputs().HasTag(kFloatTag));
-  cc->Inputs().Tag("FLOAT").Set<float>();
+  cc->Inputs().Tag(kFloatTag).Set<float>();
 
-  if (cc->Outputs().HasTag("FLAG")) {
+  if (cc->Outputs().HasTag(kFlagTag)) {
-    cc->Outputs().Tag("FLAG").Set<bool>();
+    cc->Outputs().Tag(kFlagTag).Set<bool>();
   }
-  if (cc->Outputs().HasTag("ACCEPT")) {
+  if (cc->Outputs().HasTag(kAcceptTag)) {
-    cc->Outputs().Tag("ACCEPT").Set<bool>();
+    cc->Outputs().Tag(kAcceptTag).Set<bool>();
   }
-  if (cc->Outputs().HasTag("REJECT")) {
+  if (cc->Outputs().HasTag(kRejectTag)) {
-    cc->Outputs().Tag("REJECT").Set<bool>();
+    cc->Outputs().Tag(kRejectTag).Set<bool>();
   }
-  if (cc->Inputs().HasTag("THRESHOLD")) {
+  if (cc->Inputs().HasTag(kThresholdTag)) {
-    cc->Inputs().Tag("THRESHOLD").Set<double>();
+    cc->Inputs().Tag(kThresholdTag).Set<double>();
   }
-  if (cc->InputSidePackets().HasTag("THRESHOLD")) {
+  if (cc->InputSidePackets().HasTag(kThresholdTag)) {
-    cc->InputSidePackets().Tag("THRESHOLD").Set<double>();
+    cc->InputSidePackets().Tag(kThresholdTag).Set<double>();
-    RET_CHECK(!cc->Inputs().HasTag("THRESHOLD"))
+    RET_CHECK(!cc->Inputs().HasTag(kThresholdTag))
         << "Using both the threshold input side packet and input stream is not "
            "supported.";
   }
@@ -92,43 +98,45 @@ absl::Status ThresholdingCalculator::Open(CalculatorContext* cc) {
   const auto& options =
       cc->Options<::mediapipe::ThresholdingCalculatorOptions>();
   if (options.has_threshold()) {
-    RET_CHECK(!cc->Inputs().HasTag("THRESHOLD"))
+    RET_CHECK(!cc->Inputs().HasTag(kThresholdTag))
         << "Using both the threshold option and input stream is not supported.";
-    RET_CHECK(!cc->InputSidePackets().HasTag("THRESHOLD"))
+    RET_CHECK(!cc->InputSidePackets().HasTag(kThresholdTag))
         << "Using both the threshold option and input side packet is not "
            "supported.";
     threshold_ = options.threshold();
   }
 
-  if (cc->InputSidePackets().HasTag("THRESHOLD")) {
+  if (cc->InputSidePackets().HasTag(kThresholdTag)) {
-    threshold_ = cc->InputSidePackets().Tag("THRESHOLD").Get<double>();
+    threshold_ = cc->InputSidePackets().Tag(kThresholdTag).Get<double>();
   }
   return absl::OkStatus();
 }
 
 absl::Status ThresholdingCalculator::Process(CalculatorContext* cc) {
-  if (cc->Inputs().HasTag("THRESHOLD") &&
+  if (cc->Inputs().HasTag(kThresholdTag) &&
-      !cc->Inputs().Tag("THRESHOLD").IsEmpty()) {
+      !cc->Inputs().Tag(kThresholdTag).IsEmpty()) {
-    threshold_ = cc->Inputs().Tag("THRESHOLD").Get<double>();
+    threshold_ = cc->Inputs().Tag(kThresholdTag).Get<double>();
   }
 
   bool accept = false;
-  RET_CHECK(!cc->Inputs().Tag("FLOAT").IsEmpty());
+  RET_CHECK(!cc->Inputs().Tag(kFloatTag).IsEmpty());
-  accept =
+  accept = static_cast<double>(cc->Inputs().Tag(kFloatTag).Get<float>()) >
-      static_cast<double>(cc->Inputs().Tag("FLOAT").Get<float>()) > threshold_;
+           threshold_;
 
-  if (cc->Outputs().HasTag("FLAG")) {
+  if (cc->Outputs().HasTag(kFlagTag)) {
-    cc->Outputs().Tag("FLAG").AddPacket(
+    cc->Outputs().Tag(kFlagTag).AddPacket(
         MakePacket<bool>(accept).At(cc->InputTimestamp()));
   }
 
-  if (accept && cc->Outputs().HasTag("ACCEPT")) {
+  if (accept && cc->Outputs().HasTag(kAcceptTag)) {
-    cc->Outputs().Tag("ACCEPT").AddPacket(
+    cc->Outputs()
-        MakePacket<bool>(true).At(cc->InputTimestamp()));
+        .Tag(kAcceptTag)
+        .AddPacket(MakePacket<bool>(true).At(cc->InputTimestamp()));
   }
-  if (!accept && cc->Outputs().HasTag("REJECT")) {
+  if (!accept && cc->Outputs().HasTag(kRejectTag)) {
-    cc->Outputs().Tag("REJECT").AddPacket(
+    cc->Outputs()
-        MakePacket<bool>(false).At(cc->InputTimestamp()));
+        .Tag(kRejectTag)
+        .AddPacket(MakePacket<bool>(false).At(cc->InputTimestamp()));
   }
 
   return absl::OkStatus();

mediapipe/calculators/util/top_k_scores_calculator.cc

@@ -39,6 +39,14 @@
 
 namespace mediapipe {
 
+constexpr char kTopKClassificationTag[] = "TOP_K_CLASSIFICATION";
+constexpr char kSummaryTag[] = "SUMMARY";
+constexpr char kClassificationsTag[] = "CLASSIFICATIONS";
+constexpr char kTopKLabelsTag[] = "TOP_K_LABELS";
+constexpr char kTopKScoresTag[] = "TOP_K_SCORES";
+constexpr char kTopKIndexesTag[] = "TOP_K_INDEXES";
+constexpr char kScoresTag[] = "SCORES";
+
 // A calculator that takes a vector of scores and returns the indexes, scores,
 // labels of the top k elements, classification protos, and summary std::string
 // (in csv format).
@@ -79,22 +87,22 @@ class TopKScoresCalculator : public CalculatorBase {
 REGISTER_CALCULATOR(TopKScoresCalculator);
 
 absl::Status TopKScoresCalculator::GetContract(CalculatorContract* cc) {
-  RET_CHECK(cc->Inputs().HasTag("SCORES"));
+  RET_CHECK(cc->Inputs().HasTag(kScoresTag));
-  cc->Inputs().Tag("SCORES").Set<std::vector<float>>();
+  cc->Inputs().Tag(kScoresTag).Set<std::vector<float>>();
-  if (cc->Outputs().HasTag("TOP_K_INDEXES")) {
+  if (cc->Outputs().HasTag(kTopKIndexesTag)) {
-    cc->Outputs().Tag("TOP_K_INDEXES").Set<std::vector<int>>();
+    cc->Outputs().Tag(kTopKIndexesTag).Set<std::vector<int>>();
   }
-  if (cc->Outputs().HasTag("TOP_K_SCORES")) {
+  if (cc->Outputs().HasTag(kTopKScoresTag)) {
-    cc->Outputs().Tag("TOP_K_SCORES").Set<std::vector<float>>();
+    cc->Outputs().Tag(kTopKScoresTag).Set<std::vector<float>>();
   }
-  if (cc->Outputs().HasTag("TOP_K_LABELS")) {
+  if (cc->Outputs().HasTag(kTopKLabelsTag)) {
-    cc->Outputs().Tag("TOP_K_LABELS").Set<std::vector<std::string>>();
+    cc->Outputs().Tag(kTopKLabelsTag).Set<std::vector<std::string>>();
   }
-  if (cc->Outputs().HasTag("CLASSIFICATIONS")) {
+  if (cc->Outputs().HasTag(kClassificationsTag)) {
-    cc->Outputs().Tag("CLASSIFICATIONS").Set<ClassificationList>();
+    cc->Outputs().Tag(kClassificationsTag).Set<ClassificationList>();
   }
-  if (cc->Outputs().HasTag("SUMMARY")) {
+  if (cc->Outputs().HasTag(kSummaryTag)) {
-    cc->Outputs().Tag("SUMMARY").Set<std::string>();
+    cc->Outputs().Tag(kSummaryTag).Set<std::string>();
   }
   return absl::OkStatus();
 }
@@ -114,7 +122,7 @@ absl::Status TopKScoresCalculator::Open(CalculatorContext* cc) {
   if (options.has_label_map_path()) {
     MP_RETURN_IF_ERROR(LoadLabelmap(options.label_map_path()));
   }
-  if (cc->Outputs().HasTag("TOP_K_LABELS")) {
+  if (cc->Outputs().HasTag(kTopKLabelsTag)) {
     RET_CHECK(!label_map_.empty());
   }
   return absl::OkStatus();
@@ -122,7 +130,7 @@ absl::Status TopKScoresCalculator::Open(CalculatorContext* cc) {
 
 absl::Status TopKScoresCalculator::Process(CalculatorContext* cc) {
   const std::vector<float>& input_vector =
-      cc->Inputs().Tag("SCORES").Get<std::vector<float>>();
+      cc->Inputs().Tag(kScoresTag).Get<std::vector<float>>();
   std::vector<int> top_k_indexes;
 
   std::vector<float> top_k_scores;
@@ -166,26 +174,26 @@ absl::Status TopKScoresCalculator::Process(CalculatorContext* cc) {
       top_k_labels.push_back(label_map_[index]);
     }
   }
-  if (cc->Outputs().HasTag("TOP_K_INDEXES")) {
+  if (cc->Outputs().HasTag(kTopKIndexesTag)) {
     cc->Outputs()
-        .Tag("TOP_K_INDEXES")
+        .Tag(kTopKIndexesTag)
         .AddPacket(MakePacket<std::vector<int>>(top_k_indexes)
                        .At(cc->InputTimestamp()));
   }
-  if (cc->Outputs().HasTag("TOP_K_SCORES")) {
+  if (cc->Outputs().HasTag(kTopKScoresTag)) {
     cc->Outputs()
-        .Tag("TOP_K_SCORES")
+        .Tag(kTopKScoresTag)
         .AddPacket(MakePacket<std::vector<float>>(top_k_scores)
                        .At(cc->InputTimestamp()));
   }
-  if (cc->Outputs().HasTag("TOP_K_LABELS")) {
+  if (cc->Outputs().HasTag(kTopKLabelsTag)) {
     cc->Outputs()
-        .Tag("TOP_K_LABELS")
+        .Tag(kTopKLabelsTag)
         .AddPacket(MakePacket<std::vector<std::string>>(top_k_labels)
                        .At(cc->InputTimestamp()));
   }
 
-  if (cc->Outputs().HasTag("SUMMARY")) {
+  if (cc->Outputs().HasTag(kSummaryTag)) {
     std::vector<std::string> results;
     for (int index = 0; index < top_k_indexes.size(); ++index) {
       if (label_map_loaded_) {
@@ -196,12 +204,13 @@ absl::Status TopKScoresCalculator::Process(CalculatorContext* cc) {
             absl::StrCat(top_k_indexes[index], ":", top_k_scores[index]));
       }
     }
-    cc->Outputs().Tag("SUMMARY").AddPacket(
+    cc->Outputs()
-        MakePacket<std::string>(absl::StrJoin(results, ","))
+        .Tag(kSummaryTag)
+        .AddPacket(MakePacket<std::string>(absl::StrJoin(results, ","))
                        .At(cc->InputTimestamp()));
   }
 
-  if (cc->Outputs().HasTag("TOP_K_CLASSIFICATION")) {
+  if (cc->Outputs().HasTag(kTopKClassificationTag)) {
     auto classification_list = absl::make_unique<ClassificationList>();
     for (int index = 0; index < top_k_indexes.size(); ++index) {
       Classification* classification =

mediapipe/calculators/util/top_k_scores_calculator_test.cc

@@ -23,6 +23,10 @@
 
 namespace mediapipe {
 
+constexpr char kTopKScoresTag[] = "TOP_K_SCORES";
+constexpr char kTopKIndexesTag[] = "TOP_K_INDEXES";
+constexpr char kScoresTag[] = "SCORES";
+
 TEST(TopKScoresCalculatorTest, TestNodeConfig) {
   CalculatorRunner runner(ParseTextProtoOrDie<CalculatorGraphConfig::Node>(R"pb(
     calculator: "TopKScoresCalculator"
@@ -55,19 +59,21 @@ TEST(TopKScoresCalculatorTest, TestTopKOnly) {
 
   std::vector<float> score_vector{0.9, 0.2, 0.3, 1.0, 0.1};
 
-  runner.MutableInputs()->Tag("SCORES").packets.push_back(
+  runner.MutableInputs()
+      ->Tag(kScoresTag)
+      .packets.push_back(
           MakePacket<std::vector<float>>(score_vector).At(Timestamp(0)));
 
   MP_ASSERT_OK(runner.Run());
   const std::vector<Packet>& indexes_outputs =
-      runner.Outputs().Tag("TOP_K_INDEXES").packets;
+      runner.Outputs().Tag(kTopKIndexesTag).packets;
   ASSERT_EQ(1, indexes_outputs.size());
   const auto& indexes = indexes_outputs[0].Get<std::vector<int>>();
   EXPECT_EQ(2, indexes.size());
   EXPECT_EQ(3, indexes[0]);
   EXPECT_EQ(0, indexes[1]);
   const std::vector<Packet>& scores_outputs =
-      runner.Outputs().Tag("TOP_K_SCORES").packets;
+      runner.Outputs().Tag(kTopKScoresTag).packets;
   ASSERT_EQ(1, scores_outputs.size());
   const auto& scores = scores_outputs[0].Get<std::vector<float>>();
   EXPECT_EQ(2, scores.size());
@@ -88,12 +94,14 @@ TEST(TopKScoresCalculatorTest, TestThresholdOnly) {
 
   std::vector<float> score_vector{0.9, 0.2, 0.3, 1.0, 0.1};
 
-  runner.MutableInputs()->Tag("SCORES").packets.push_back(
+  runner.MutableInputs()
+      ->Tag(kScoresTag)
+      .packets.push_back(
           MakePacket<std::vector<float>>(score_vector).At(Timestamp(0)));
 
   MP_ASSERT_OK(runner.Run());
   const std::vector<Packet>& indexes_outputs =
-      runner.Outputs().Tag("TOP_K_INDEXES").packets;
+      runner.Outputs().Tag(kTopKIndexesTag).packets;
   ASSERT_EQ(1, indexes_outputs.size());
   const auto& indexes = indexes_outputs[0].Get<std::vector<int>>();
   EXPECT_EQ(4, indexes.size());
@@ -102,7 +110,7 @@ TEST(TopKScoresCalculatorTest, TestThresholdOnly) {
   EXPECT_EQ(2, indexes[2]);
   EXPECT_EQ(1, indexes[3]);
   const std::vector<Packet>& scores_outputs =
-      runner.Outputs().Tag("TOP_K_SCORES").packets;
+      runner.Outputs().Tag(kTopKScoresTag).packets;
   ASSERT_EQ(1, scores_outputs.size());
   const auto& scores = scores_outputs[0].Get<std::vector<float>>();
   EXPECT_EQ(4, scores.size());
@@ -125,12 +133,14 @@ TEST(TopKScoresCalculatorTest, TestBothTopKAndThreshold) {
 
   std::vector<float> score_vector{0.9, 0.2, 0.3, 1.0, 0.1};
 
-  runner.MutableInputs()->Tag("SCORES").packets.push_back(
+  runner.MutableInputs()
+      ->Tag(kScoresTag)
+      .packets.push_back(
           MakePacket<std::vector<float>>(score_vector).At(Timestamp(0)));
 
   MP_ASSERT_OK(runner.Run());
   const std::vector<Packet>& indexes_outputs =
-      runner.Outputs().Tag("TOP_K_INDEXES").packets;
+      runner.Outputs().Tag(kTopKIndexesTag).packets;
   ASSERT_EQ(1, indexes_outputs.size());
   const auto& indexes = indexes_outputs[0].Get<std::vector<int>>();
   EXPECT_EQ(3, indexes.size());
@@ -138,7 +148,7 @@ TEST(TopKScoresCalculatorTest, TestBothTopKAndThreshold) {
   EXPECT_EQ(0, indexes[1]);
   EXPECT_EQ(2, indexes[2]);
   const std::vector<Packet>& scores_outputs =
-      runner.Outputs().Tag("TOP_K_SCORES").packets;
+      runner.Outputs().Tag(kTopKScoresTag).packets;
   ASSERT_EQ(1, scores_outputs.size());
   const auto& scores = scores_outputs[0].Get<std::vector<float>>();
   EXPECT_EQ(3, scores.size());

mediapipe/calculators/video/box_detector_calculator.cc

@@ -47,6 +47,21 @@
 
 namespace mediapipe {
 
+constexpr char kFrameAlignmentTag[] = "FRAME_ALIGNMENT";
+constexpr char kOutputIndexFilenameTag[] = "OUTPUT_INDEX_FILENAME";
+constexpr char kIndexProtoStringTag[] = "INDEX_PROTO_STRING";
+constexpr char kVizTag[] = "VIZ";
+constexpr char kBoxesTag[] = "BOXES";
+constexpr char kReacqSwitchTag[] = "REACQ_SWITCH";
+constexpr char kCancelObjectIdTag[] = "CANCEL_OBJECT_ID";
+constexpr char kAddIndexTag[] = "ADD_INDEX";
+constexpr char kImageSizeTag[] = "IMAGE_SIZE";
+constexpr char kDescriptorsTag[] = "DESCRIPTORS";
+constexpr char kFeaturesTag[] = "FEATURES";
+constexpr char kVideoTag[] = "VIDEO";
+constexpr char kTrackedBoxesTag[] = "TRACKED_BOXES";
+constexpr char kTrackingTag[] = "TRACKING";
+
 // A calculator to detect reappeared box positions from single frame.
 //
 // Input stream:
@@ -110,66 +125,66 @@ class BoxDetectorCalculator : public CalculatorBase {
 REGISTER_CALCULATOR(BoxDetectorCalculator);
 
 absl::Status BoxDetectorCalculator::GetContract(CalculatorContract* cc) {
-  if (cc->Inputs().HasTag("TRACKING")) {
+  if (cc->Inputs().HasTag(kTrackingTag)) {
-    cc->Inputs().Tag("TRACKING").Set<TrackingData>();
+    cc->Inputs().Tag(kTrackingTag).Set<TrackingData>();
   }
 
-  if (cc->Inputs().HasTag("TRACKED_BOXES")) {
+  if (cc->Inputs().HasTag(kTrackedBoxesTag)) {
-    cc->Inputs().Tag("TRACKED_BOXES").Set<TimedBoxProtoList>();
+    cc->Inputs().Tag(kTrackedBoxesTag).Set<TimedBoxProtoList>();
   }
 
-  if (cc->Inputs().HasTag("VIDEO")) {
+  if (cc->Inputs().HasTag(kVideoTag)) {
-    cc->Inputs().Tag("VIDEO").Set<ImageFrame>();
+    cc->Inputs().Tag(kVideoTag).Set<ImageFrame>();
   }
 
-  if (cc->Inputs().HasTag("FEATURES")) {
+  if (cc->Inputs().HasTag(kFeaturesTag)) {
-    RET_CHECK(cc->Inputs().HasTag("DESCRIPTORS"))
+    RET_CHECK(cc->Inputs().HasTag(kDescriptorsTag))
         << "FEATURES and DESCRIPTORS need to be specified together.";
-    cc->Inputs().Tag("FEATURES").Set<std::vector<cv::KeyPoint>>();
+    cc->Inputs().Tag(kFeaturesTag).Set<std::vector<cv::KeyPoint>>();
   }
 
-  if (cc->Inputs().HasTag("DESCRIPTORS")) {
+  if (cc->Inputs().HasTag(kDescriptorsTag)) {
-    RET_CHECK(cc->Inputs().HasTag("FEATURES"))
+    RET_CHECK(cc->Inputs().HasTag(kFeaturesTag))
         << "FEATURES and DESCRIPTORS need to be specified together.";
-    cc->Inputs().Tag("DESCRIPTORS").Set<std::vector<float>>();
+    cc->Inputs().Tag(kDescriptorsTag).Set<std::vector<float>>();
   }
 
-  if (cc->Inputs().HasTag("IMAGE_SIZE")) {
+  if (cc->Inputs().HasTag(kImageSizeTag)) {
-    cc->Inputs().Tag("IMAGE_SIZE").Set<std::pair<int, int>>();
+    cc->Inputs().Tag(kImageSizeTag).Set<std::pair<int, int>>();
   }
 
-  if (cc->Inputs().HasTag("ADD_INDEX")) {
+  if (cc->Inputs().HasTag(kAddIndexTag)) {
-    cc->Inputs().Tag("ADD_INDEX").Set<std::string>();
+    cc->Inputs().Tag(kAddIndexTag).Set<std::string>();
   }
 
-  if (cc->Inputs().HasTag("CANCEL_OBJECT_ID")) {
+  if (cc->Inputs().HasTag(kCancelObjectIdTag)) {
-    cc->Inputs().Tag("CANCEL_OBJECT_ID").Set<int>();
+    cc->Inputs().Tag(kCancelObjectIdTag).Set<int>();
   }
 
-  if (cc->Inputs().HasTag("REACQ_SWITCH")) {
+  if (cc->Inputs().HasTag(kReacqSwitchTag)) {
-    cc->Inputs().Tag("REACQ_SWITCH").Set<bool>();
+    cc->Inputs().Tag(kReacqSwitchTag).Set<bool>();
   }
 
-  if (cc->Outputs().HasTag("BOXES")) {
+  if (cc->Outputs().HasTag(kBoxesTag)) {
-    cc->Outputs().Tag("BOXES").Set<TimedBoxProtoList>();
+    cc->Outputs().Tag(kBoxesTag).Set<TimedBoxProtoList>();
   }
 
-  if (cc->Outputs().HasTag("VIZ")) {
+  if (cc->Outputs().HasTag(kVizTag)) {
-    RET_CHECK(cc->Inputs().HasTag("VIDEO"))
+    RET_CHECK(cc->Inputs().HasTag(kVideoTag))
         << "Output stream VIZ requires VIDEO to be present.";
-    cc->Outputs().Tag("VIZ").Set<ImageFrame>();
+    cc->Outputs().Tag(kVizTag).Set<ImageFrame>();
   }
 
-  if (cc->InputSidePackets().HasTag("INDEX_PROTO_STRING")) {
+  if (cc->InputSidePackets().HasTag(kIndexProtoStringTag)) {
-    cc->InputSidePackets().Tag("INDEX_PROTO_STRING").Set<std::string>();
+    cc->InputSidePackets().Tag(kIndexProtoStringTag).Set<std::string>();
   }
 
-  if (cc->InputSidePackets().HasTag("OUTPUT_INDEX_FILENAME")) {
+  if (cc->InputSidePackets().HasTag(kOutputIndexFilenameTag)) {
-    cc->InputSidePackets().Tag("OUTPUT_INDEX_FILENAME").Set<std::string>();
+    cc->InputSidePackets().Tag(kOutputIndexFilenameTag).Set<std::string>();
   }
 
-  if (cc->InputSidePackets().HasTag("FRAME_ALIGNMENT")) {
+  if (cc->InputSidePackets().HasTag(kFrameAlignmentTag)) {
-    cc->InputSidePackets().Tag("FRAME_ALIGNMENT").Set<int>();
+    cc->InputSidePackets().Tag(kFrameAlignmentTag).Set<int>();
   }
 
   return absl::OkStatus();
@@ -179,10 +194,10 @@ absl::Status BoxDetectorCalculator::Open(CalculatorContext* cc) {
   options_ = cc->Options<BoxDetectorCalculatorOptions>();
   box_detector_ = BoxDetectorInterface::Create(options_.detector_options());
 
-  if (cc->InputSidePackets().HasTag("INDEX_PROTO_STRING")) {
+  if (cc->InputSidePackets().HasTag(kIndexProtoStringTag)) {
     BoxDetectorIndex predefined_index;
     if (!predefined_index.ParseFromString(cc->InputSidePackets()
-                                              .Tag("INDEX_PROTO_STRING")
+                                              .Tag(kIndexProtoStringTag)
                                               .Get<std::string>())) {
       LOG(FATAL) << "failed to parse BoxDetectorIndex from INDEX_PROTO_STRING";
     }
@@ -202,12 +217,13 @@ absl::Status BoxDetectorCalculator::Open(CalculatorContext* cc) {
     box_detector_->AddBoxDetectorIndex(predefined_index);
   }
 
-  if (cc->InputSidePackets().HasTag("OUTPUT_INDEX_FILENAME")) {
+  if (cc->InputSidePackets().HasTag(kOutputIndexFilenameTag)) {
     write_index_ = true;
   }
 
-  if (cc->InputSidePackets().HasTag("FRAME_ALIGNMENT")) {
+  if (cc->InputSidePackets().HasTag(kFrameAlignmentTag)) {
-    frame_alignment_ = cc->InputSidePackets().Tag("FRAME_ALIGNMENT").Get<int>();
+    frame_alignment_ =
+        cc->InputSidePackets().Tag(kFrameAlignmentTag).Get<int>();
   }
 
   return absl::OkStatus();
@@ -218,16 +234,16 @@ absl::Status BoxDetectorCalculator::Process(CalculatorContext* cc) {
   const int64 timestamp_msec = timestamp.Value() / 1000;
 
   InputStream* cancel_object_id_stream =
-      cc->Inputs().HasTag("CANCEL_OBJECT_ID")
+      cc->Inputs().HasTag(kCancelObjectIdTag)
-          ? &(cc->Inputs().Tag("CANCEL_OBJECT_ID"))
+          ? &(cc->Inputs().Tag(kCancelObjectIdTag))
           : nullptr;
   if (cancel_object_id_stream && !cancel_object_id_stream->IsEmpty()) {
     const int cancel_object_id = cancel_object_id_stream->Get<int>();
     box_detector_->CancelBoxDetection(cancel_object_id);
   }
 
-  InputStream* add_index_stream = cc->Inputs().HasTag("ADD_INDEX")
+  InputStream* add_index_stream = cc->Inputs().HasTag(kAddIndexTag)
-                                      ? &(cc->Inputs().Tag("ADD_INDEX"))
+                                      ? &(cc->Inputs().Tag(kAddIndexTag))
                                       : nullptr;
   if (add_index_stream && !add_index_stream->IsEmpty()) {
     BoxDetectorIndex predefined_index;
@@ -238,8 +254,8 @@ absl::Status BoxDetectorCalculator::Process(CalculatorContext* cc) {
     box_detector_->AddBoxDetectorIndex(predefined_index);
   }
 
-  InputStream* reacq_switch_stream = cc->Inputs().HasTag("REACQ_SWITCH")
+  InputStream* reacq_switch_stream = cc->Inputs().HasTag(kReacqSwitchTag)
-                                         ? &(cc->Inputs().Tag("REACQ_SWITCH"))
+                                         ? &(cc->Inputs().Tag(kReacqSwitchTag))
                                          : nullptr;
   if (reacq_switch_stream && !reacq_switch_stream->IsEmpty()) {
     detector_switch_ = reacq_switch_stream->Get<bool>();
@@ -249,16 +265,16 @@ absl::Status BoxDetectorCalculator::Process(CalculatorContext* cc) {
     return absl::OkStatus();
   }
 
-  InputStream* track_stream = cc->Inputs().HasTag("TRACKING")
+  InputStream* track_stream = cc->Inputs().HasTag(kTrackingTag)
-                                  ? &(cc->Inputs().Tag("TRACKING"))
+                                  ? &(cc->Inputs().Tag(kTrackingTag))
                                   : nullptr;
   InputStream* video_stream =
-      cc->Inputs().HasTag("VIDEO") ? &(cc->Inputs().Tag("VIDEO")) : nullptr;
+      cc->Inputs().HasTag(kVideoTag) ? &(cc->Inputs().Tag(kVideoTag)) : nullptr;
-  InputStream* feature_stream = cc->Inputs().HasTag("FEATURES")
+  InputStream* feature_stream = cc->Inputs().HasTag(kFeaturesTag)
-                                    ? &(cc->Inputs().Tag("FEATURES"))
+                                    ? &(cc->Inputs().Tag(kFeaturesTag))
                                     : nullptr;
-  InputStream* descriptor_stream = cc->Inputs().HasTag("DESCRIPTORS")
+  InputStream* descriptor_stream = cc->Inputs().HasTag(kDescriptorsTag)
-                                       ? &(cc->Inputs().Tag("DESCRIPTORS"))
+                                       ? &(cc->Inputs().Tag(kDescriptorsTag))
                                        : nullptr;
 
   CHECK(track_stream != nullptr || video_stream != nullptr ||
@@ -266,8 +282,9 @@ absl::Status BoxDetectorCalculator::Process(CalculatorContext* cc) {
       << "One and only one of {tracking_data, input image frame, "
          "feature/descriptor} need to be valid.";
 
-  InputStream* tracked_boxes_stream = cc->Inputs().HasTag("TRACKED_BOXES")
+  InputStream* tracked_boxes_stream =
-                                          ? &(cc->Inputs().Tag("TRACKED_BOXES"))
+      cc->Inputs().HasTag(kTrackedBoxesTag)
+          ? &(cc->Inputs().Tag(kTrackedBoxesTag))
           : nullptr;
   std::unique_ptr<TimedBoxProtoList> detected_boxes(new TimedBoxProtoList());
 
@@ -309,7 +326,7 @@ absl::Status BoxDetectorCalculator::Process(CalculatorContext* cc) {
     }
 
     const auto& image_size =
-        cc->Inputs().Tag("IMAGE_SIZE").Get<std::pair<int, int>>();
+        cc->Inputs().Tag(kImageSizeTag).Get<std::pair<int, int>>();
     float inv_scale = 1.0f / std::max(image_size.first, image_size.second);
 
     TimedBoxProtoList tracked_boxes;
@@ -359,7 +376,7 @@ absl::Status BoxDetectorCalculator::Process(CalculatorContext* cc) {
         detected_boxes.get());
   }
 
-  if (cc->Outputs().HasTag("VIZ")) {
+  if (cc->Outputs().HasTag(kVizTag)) {
     cv::Mat viz_view;
     std::unique_ptr<ImageFrame> viz_frame;
     if (video_stream != nullptr && !video_stream->IsEmpty()) {
@@ -370,11 +387,11 @@ absl::Status BoxDetectorCalculator::Process(CalculatorContext* cc) {
     for (const auto& box : detected_boxes->box()) {
       RenderBox(box, &viz_view);
     }
-    cc->Outputs().Tag("VIZ").Add(viz_frame.release(), timestamp);
+    cc->Outputs().Tag(kVizTag).Add(viz_frame.release(), timestamp);
   }
 
-  if (cc->Outputs().HasTag("BOXES")) {
+  if (cc->Outputs().HasTag(kBoxesTag)) {
-    cc->Outputs().Tag("BOXES").Add(detected_boxes.release(), timestamp);
+    cc->Outputs().Tag(kBoxesTag).Add(detected_boxes.release(), timestamp);
   }
 
   return absl::OkStatus();
@@ -384,7 +401,7 @@ absl::Status BoxDetectorCalculator::Close(CalculatorContext* cc) {
   if (write_index_) {
     BoxDetectorIndex index = box_detector_->ObtainBoxDetectorIndex();
     MEDIAPIPE_CHECK_OK(mediapipe::file::SetContents(
-        cc->InputSidePackets().Tag("OUTPUT_INDEX_FILENAME").Get<std::string>(),
+        cc->InputSidePackets().Tag(kOutputIndexFilenameTag).Get<std::string>(),
         index.SerializeAsString()));
   }
   return absl::OkStatus();

mediapipe/calculators/video/box_tracker_calculator.cc

@@ -293,6 +293,22 @@ const int BoxTrackerCalculator::kMotionBoxPathMinQueueSize = 2;
 
 namespace {
 
+constexpr char kCacheDirTag[] = "CACHE_DIR";
+constexpr char kInitialPosTag[] = "INITIAL_POS";
+constexpr char kRaBoxesTag[] = "RA_BOXES";
+constexpr char kBoxesTag[] = "BOXES";
+constexpr char kVizTag[] = "VIZ";
+constexpr char kRaTrackProtoStringTag[] = "RA_TRACK_PROTO_STRING";
+constexpr char kRaTrackTag[] = "RA_TRACK";
+constexpr char kCancelObjectIdTag[] = "CANCEL_OBJECT_ID";
+constexpr char kRestartPosTag[] = "RESTART_POS";
+constexpr char kStartPosProtoStringTag[] = "START_POS_PROTO_STRING";
+constexpr char kStartPosTag[] = "START_POS";
+constexpr char kStartTag[] = "START";
+constexpr char kVideoTag[] = "VIDEO";
+constexpr char kTrackTimeTag[] = "TRACK_TIME";
+constexpr char kTrackingTag[] = "TRACKING";
+
 // Convert box position according to rotation angle in degrees.
 void ConvertCoordinateForRotation(float in_top, float in_left, float in_bottom,
                                   float in_right, int rotation, float* out_top,
@@ -374,78 +390,78 @@ void AddStateToPath(const MotionBoxState& state, int64 time_msec,
 }  // namespace.
 
 absl::Status BoxTrackerCalculator::GetContract(CalculatorContract* cc) {
-  if (cc->Inputs().HasTag("TRACKING")) {
+  if (cc->Inputs().HasTag(kTrackingTag)) {
-    cc->Inputs().Tag("TRACKING").Set<TrackingData>();
+    cc->Inputs().Tag(kTrackingTag).Set<TrackingData>();
   }
 
-  if (cc->Inputs().HasTag("TRACK_TIME")) {
+  if (cc->Inputs().HasTag(kTrackTimeTag)) {
-    RET_CHECK(cc->Inputs().HasTag("TRACKING"))
+    RET_CHECK(cc->Inputs().HasTag(kTrackingTag))
         << "TRACK_TIME needs TRACKING input";
-    cc->Inputs().Tag("TRACK_TIME").SetAny();
+    cc->Inputs().Tag(kTrackTimeTag).SetAny();
   }
 
-  if (cc->Inputs().HasTag("VIDEO")) {
+  if (cc->Inputs().HasTag(kVideoTag)) {
-    cc->Inputs().Tag("VIDEO").Set<ImageFrame>();
+    cc->Inputs().Tag(kVideoTag).Set<ImageFrame>();
   }
 
-  if (cc->Inputs().HasTag("START")) {
+  if (cc->Inputs().HasTag(kStartTag)) {
     // Actual packet content does not matter.
-    cc->Inputs().Tag("START").SetAny();
+    cc->Inputs().Tag(kStartTag).SetAny();
   }
 
-  if (cc->Inputs().HasTag("START_POS")) {
+  if (cc->Inputs().HasTag(kStartPosTag)) {
-    cc->Inputs().Tag("START_POS").Set<TimedBoxProtoList>();
+    cc->Inputs().Tag(kStartPosTag).Set<TimedBoxProtoList>();
   }
 
-  if (cc->Inputs().HasTag("START_POS_PROTO_STRING")) {
+  if (cc->Inputs().HasTag(kStartPosProtoStringTag)) {
-    cc->Inputs().Tag("START_POS_PROTO_STRING").Set<std::string>();
+    cc->Inputs().Tag(kStartPosProtoStringTag).Set<std::string>();
   }
 
-  if (cc->Inputs().HasTag("RESTART_POS")) {
+  if (cc->Inputs().HasTag(kRestartPosTag)) {
-    cc->Inputs().Tag("RESTART_POS").Set<TimedBoxProtoList>();
+    cc->Inputs().Tag(kRestartPosTag).Set<TimedBoxProtoList>();
   }
 
-  if (cc->Inputs().HasTag("CANCEL_OBJECT_ID")) {
+  if (cc->Inputs().HasTag(kCancelObjectIdTag)) {
-    cc->Inputs().Tag("CANCEL_OBJECT_ID").Set<int>();
+    cc->Inputs().Tag(kCancelObjectIdTag).Set<int>();
   }
 
-  if (cc->Inputs().HasTag("RA_TRACK")) {
+  if (cc->Inputs().HasTag(kRaTrackTag)) {
-    cc->Inputs().Tag("RA_TRACK").Set<TimedBoxProtoList>();
+    cc->Inputs().Tag(kRaTrackTag).Set<TimedBoxProtoList>();
   }
 
-  if (cc->Inputs().HasTag("RA_TRACK_PROTO_STRING")) {
+  if (cc->Inputs().HasTag(kRaTrackProtoStringTag)) {
-    cc->Inputs().Tag("RA_TRACK_PROTO_STRING").Set<std::string>();
+    cc->Inputs().Tag(kRaTrackProtoStringTag).Set<std::string>();
   }
 
-  if (cc->Outputs().HasTag("VIZ")) {
+  if (cc->Outputs().HasTag(kVizTag)) {
-    RET_CHECK(cc->Inputs().HasTag("VIDEO"))
+    RET_CHECK(cc->Inputs().HasTag(kVideoTag))
         << "Output stream VIZ requires VIDEO to be present.";
-    cc->Outputs().Tag("VIZ").Set<ImageFrame>();
+    cc->Outputs().Tag(kVizTag).Set<ImageFrame>();
   }
 
-  if (cc->Outputs().HasTag("BOXES")) {
+  if (cc->Outputs().HasTag(kBoxesTag)) {
-    cc->Outputs().Tag("BOXES").Set<TimedBoxProtoList>();
+    cc->Outputs().Tag(kBoxesTag).Set<TimedBoxProtoList>();
   }
 
-  if (cc->Outputs().HasTag("RA_BOXES")) {
+  if (cc->Outputs().HasTag(kRaBoxesTag)) {
-    cc->Outputs().Tag("RA_BOXES").Set<TimedBoxProtoList>();
+    cc->Outputs().Tag(kRaBoxesTag).Set<TimedBoxProtoList>();
   }
 
 #if defined(__ANDROID__) || defined(__APPLE__) || defined(__EMSCRIPTEN__)
-  RET_CHECK(!cc->InputSidePackets().HasTag("INITIAL_POS"))
+  RET_CHECK(!cc->InputSidePackets().HasTag(kInitialPosTag))
       << "Unsupported on mobile";
 #else
-  if (cc->InputSidePackets().HasTag("INITIAL_POS")) {
+  if (cc->InputSidePackets().HasTag(kInitialPosTag)) {
-    cc->InputSidePackets().Tag("INITIAL_POS").Set<std::string>();
+    cc->InputSidePackets().Tag(kInitialPosTag).Set<std::string>();
   }
 #endif  // defined(__ANDROID__) || defined(__APPLE__) || defined(__EMSCRIPTEN__)
 
-  if (cc->InputSidePackets().HasTag("CACHE_DIR")) {
+  if (cc->InputSidePackets().HasTag(kCacheDirTag)) {
-    cc->InputSidePackets().Tag("CACHE_DIR").Set<std::string>();
+    cc->InputSidePackets().Tag(kCacheDirTag).Set<std::string>();
   }
 
-  RET_CHECK(cc->Inputs().HasTag("TRACKING") !=
+  RET_CHECK(cc->Inputs().HasTag(kTrackingTag) !=
-            cc->InputSidePackets().HasTag("CACHE_DIR"))
+            cc->InputSidePackets().HasTag(kCacheDirTag))
       << "Either TRACKING or CACHE_DIR needs to be specified.";
 
   if (cc->InputSidePackets().HasTag(kOptionsTag)) {
@@ -459,7 +475,7 @@ absl::Status BoxTrackerCalculator::Open(CalculatorContext* cc) {
   options_ = tool::RetrieveOptions(cc->Options<BoxTrackerCalculatorOptions>(),
                                    cc->InputSidePackets(), kOptionsTag);
 
-  RET_CHECK(!cc->InputSidePackets().HasTag("INITIAL_POS") ||
+  RET_CHECK(!cc->InputSidePackets().HasTag(kInitialPosTag) ||
             !options_.has_initial_position())
       << "Can not specify initial position as side packet and via options";
 
@@ -468,11 +484,11 @@ absl::Status BoxTrackerCalculator::Open(CalculatorContext* cc) {
   }
 
 #if !defined(__ANDROID__) && !defined(__APPLE__) && !defined(__EMSCRIPTEN__)
-  if (cc->InputSidePackets().HasTag("INITIAL_POS")) {
+  if (cc->InputSidePackets().HasTag(kInitialPosTag)) {
     LOG(INFO) << "Parsing: "
-              << cc->InputSidePackets().Tag("INITIAL_POS").Get<std::string>();
+              << cc->InputSidePackets().Tag(kInitialPosTag).Get<std::string>();
     initial_pos_ = ParseTextProtoOrDie<TimedBoxProtoList>(
-        cc->InputSidePackets().Tag("INITIAL_POS").Get<std::string>());
+        cc->InputSidePackets().Tag(kInitialPosTag).Get<std::string>());
   }
 #endif  // !defined(__ANDROID__) && !defined(__APPLE__) &&
         // !defined(__EMSCRIPTEN__)
@@ -484,10 +500,11 @@ absl::Status BoxTrackerCalculator::Open(CalculatorContext* cc) {
   }
 
   visualize_tracking_data_ =
-      options_.visualize_tracking_data() && cc->Outputs().HasTag("VIZ");
+      options_.visualize_tracking_data() && cc->Outputs().HasTag(kVizTag);
-  visualize_state_ = options_.visualize_state() && cc->Outputs().HasTag("VIZ");
+  visualize_state_ =
+      options_.visualize_state() && cc->Outputs().HasTag(kVizTag);
   visualize_internal_state_ =
-      options_.visualize_internal_state() && cc->Outputs().HasTag("VIZ");
+      options_.visualize_internal_state() && cc->Outputs().HasTag(kVizTag);
 
   // Force recording of internal state for rendering.
   if (visualize_internal_state_) {
@@ -500,8 +517,8 @@ absl::Status BoxTrackerCalculator::Open(CalculatorContext* cc) {
     options_.mutable_tracker_options()->set_record_path_states(true);
   }
 
-  if (cc->InputSidePackets().HasTag("CACHE_DIR")) {
+  if (cc->InputSidePackets().HasTag(kCacheDirTag)) {
-    cache_dir_ = cc->InputSidePackets().Tag("CACHE_DIR").Get<std::string>();
+    cache_dir_ = cc->InputSidePackets().Tag(kCacheDirTag).Get<std::string>();
     RET_CHECK(!cache_dir_.empty());
     box_tracker_.reset(new BoxTracker(cache_dir_, options_.tracker_options()));
   } else {
@@ -511,7 +528,7 @@ absl::Status BoxTrackerCalculator::Open(CalculatorContext* cc) {
   }
 
   if (options_.streaming_track_data_cache_size() > 0) {
-    RET_CHECK(!cc->InputSidePackets().HasTag("CACHE_DIR"))
+    RET_CHECK(!cc->InputSidePackets().HasTag(kCacheDirTag))
         << "Streaming mode not compatible with cache dir.";
   }
 
@@ -533,11 +550,11 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
     return absl::OkStatus();
   }
 
-  InputStream* track_stream = cc->Inputs().HasTag("TRACKING")
+  InputStream* track_stream = cc->Inputs().HasTag(kTrackingTag)
-                                  ? &(cc->Inputs().Tag("TRACKING"))
+                                  ? &(cc->Inputs().Tag(kTrackingTag))
                                   : nullptr;
-  InputStream* track_time_stream = cc->Inputs().HasTag("TRACK_TIME")
+  InputStream* track_time_stream = cc->Inputs().HasTag(kTrackTimeTag)
-                                       ? &(cc->Inputs().Tag("TRACK_TIME"))
+                                       ? &(cc->Inputs().Tag(kTrackTimeTag))
                                        : nullptr;
 
   // Cache tracking data if possible.
@@ -562,8 +579,8 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
     }
   }
 
-  InputStream* start_pos_stream = cc->Inputs().HasTag("START_POS")
+  InputStream* start_pos_stream = cc->Inputs().HasTag(kStartPosTag)
-                                      ? &(cc->Inputs().Tag("START_POS"))
+                                      ? &(cc->Inputs().Tag(kStartPosTag))
                                       : nullptr;
 
   MotionBoxMap fast_forward_boxes;
@@ -575,8 +592,8 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
   }
 
   InputStream* start_pos_proto_string_stream =
-      cc->Inputs().HasTag("START_POS_PROTO_STRING")
+      cc->Inputs().HasTag(kStartPosProtoStringTag)
-          ? &(cc->Inputs().Tag("START_POS_PROTO_STRING"))
+          ? &(cc->Inputs().Tag(kStartPosProtoStringTag))
           : nullptr;
   if (start_pos_stream == nullptr || start_pos_stream->IsEmpty()) {
     if (start_pos_proto_string_stream &&
@@ -589,8 +606,8 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
     }
   }
 
-  InputStream* restart_pos_stream = cc->Inputs().HasTag("RESTART_POS")
+  InputStream* restart_pos_stream = cc->Inputs().HasTag(kRestartPosTag)
-                                        ? &(cc->Inputs().Tag("RESTART_POS"))
+                                        ? &(cc->Inputs().Tag(kRestartPosTag))
                                         : nullptr;
 
   if (restart_pos_stream && !restart_pos_stream->IsEmpty()) {
@@ -600,8 +617,8 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
   }
 
   InputStream* cancel_object_id_stream =
-      cc->Inputs().HasTag("CANCEL_OBJECT_ID")
+      cc->Inputs().HasTag(kCancelObjectIdTag)
-          ? &(cc->Inputs().Tag("CANCEL_OBJECT_ID"))
+          ? &(cc->Inputs().Tag(kCancelObjectIdTag))
           : nullptr;
   if (cancel_object_id_stream && !cancel_object_id_stream->IsEmpty()) {
     const int cancel_object_id = cancel_object_id_stream->Get<int>();
@@ -616,8 +633,8 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
 
   TrackingData track_data_to_render;
 
-  if (cc->Outputs().HasTag("VIZ")) {
+  if (cc->Outputs().HasTag(kVizTag)) {
-    InputStream* video_stream = &(cc->Inputs().Tag("VIDEO"));
+    InputStream* video_stream = &(cc->Inputs().Tag(kVideoTag));
     if (!video_stream->IsEmpty()) {
       input_view = formats::MatView(&video_stream->Get<ImageFrame>());
 
@@ -745,7 +762,7 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
       ++frame_num_since_reset_;
 
       // Generate results for queued up request.
-      if (cc->Outputs().HasTag("BOXES") && !queued_track_requests_.empty()) {
+      if (cc->Outputs().HasTag(kBoxesTag) && !queued_track_requests_.empty()) {
         for (int j = 0; j < queued_track_requests_.size(); ++j) {
           const Timestamp& past_time = queued_track_requests_[j];
           RET_CHECK(past_time.Value() < timestamp.Value())
@@ -770,7 +787,7 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
           }
 
           // Output for every time.
-          cc->Outputs().Tag("BOXES").Add(past_box_list.release(), past_time);
+          cc->Outputs().Tag(kBoxesTag).Add(past_box_list.release(), past_time);
         }
 
         queued_track_requests_.clear();
@@ -845,8 +862,8 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
   }
 
   // Handle random access track requests.
-  InputStream* ra_track_stream = cc->Inputs().HasTag("RA_TRACK")
+  InputStream* ra_track_stream = cc->Inputs().HasTag(kRaTrackTag)
-                                     ? &(cc->Inputs().Tag("RA_TRACK"))
+                                     ? &(cc->Inputs().Tag(kRaTrackTag))
                                      : nullptr;
 
   if (ra_track_stream && !ra_track_stream->IsEmpty()) {
@@ -861,8 +878,8 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
   }
 
   InputStream* ra_track_proto_string_stream =
-      cc->Inputs().HasTag("RA_TRACK_PROTO_STRING")
+      cc->Inputs().HasTag(kRaTrackProtoStringTag)
-          ? &(cc->Inputs().Tag("RA_TRACK_PROTO_STRING"))
+          ? &(cc->Inputs().Tag(kRaTrackProtoStringTag))
           : nullptr;
   if (ra_track_stream == nullptr || ra_track_stream->IsEmpty()) {
     if (ra_track_proto_string_stream &&
@@ -881,15 +898,15 @@ absl::Status BoxTrackerCalculator::Process(CalculatorContext* cc) {
 
   // Always output in batch, only output in streaming if tracking data
   // is present (might be in fast forward mode instead).
-  if (cc->Outputs().HasTag("BOXES") &&
+  if (cc->Outputs().HasTag(kBoxesTag) &&
       (box_tracker_ || !track_stream->IsEmpty())) {
     std::unique_ptr<TimedBoxProtoList> boxes(new TimedBoxProtoList());
     *boxes = std::move(box_track_list);
-    cc->Outputs().Tag("BOXES").Add(boxes.release(), timestamp);
+    cc->Outputs().Tag(kBoxesTag).Add(boxes.release(), timestamp);
   }
 
   if (viz_frame) {
-    cc->Outputs().Tag("VIZ").Add(viz_frame.release(), timestamp);
+    cc->Outputs().Tag(kVizTag).Add(viz_frame.release(), timestamp);
   }
 
   return absl::OkStatus();
@@ -1001,7 +1018,7 @@ void BoxTrackerCalculator::OutputRandomAccessTrack(
   }
 
   cc->Outputs()
-      .Tag("RA_BOXES")
+      .Tag(kRaBoxesTag)
       .Add(result_list.release(), cc->InputTimestamp());
 }
 

mediapipe/calculators/video/flow_packager_calculator.cc

@@ -29,6 +29,13 @@
 
 namespace mediapipe {
 
+constexpr char kCacheDirTag[] = "CACHE_DIR";
+constexpr char kCompleteTag[] = "COMPLETE";
+constexpr char kTrackingChunkTag[] = "TRACKING_CHUNK";
+constexpr char kTrackingTag[] = "TRACKING";
+constexpr char kCameraTag[] = "CAMERA";
+constexpr char kFlowTag[] = "FLOW";
+
 using mediapipe::CameraMotion;
 using mediapipe::FlowPackager;
 using mediapipe::RegionFlowFeatureList;
@@ -91,27 +98,27 @@ class FlowPackagerCalculator : public CalculatorBase {
 REGISTER_CALCULATOR(FlowPackagerCalculator);
 
 absl::Status FlowPackagerCalculator::GetContract(CalculatorContract* cc) {
-  if (!cc->Inputs().HasTag("FLOW")) {
+  if (!cc->Inputs().HasTag(kFlowTag)) {
     return tool::StatusFail("No input flow was specified.");
   }
 
-  cc->Inputs().Tag("FLOW").Set<RegionFlowFeatureList>();
+  cc->Inputs().Tag(kFlowTag).Set<RegionFlowFeatureList>();
 
-  if (cc->Inputs().HasTag("CAMERA")) {
+  if (cc->Inputs().HasTag(kCameraTag)) {
-    cc->Inputs().Tag("CAMERA").Set<CameraMotion>();
+    cc->Inputs().Tag(kCameraTag).Set<CameraMotion>();
   }
-  if (cc->Outputs().HasTag("TRACKING")) {
+  if (cc->Outputs().HasTag(kTrackingTag)) {
-    cc->Outputs().Tag("TRACKING").Set<TrackingData>();
+    cc->Outputs().Tag(kTrackingTag).Set<TrackingData>();
   }
-  if (cc->Outputs().HasTag("TRACKING_CHUNK")) {
+  if (cc->Outputs().HasTag(kTrackingChunkTag)) {
-    cc->Outputs().Tag("TRACKING_CHUNK").Set<TrackingDataChunk>();
+    cc->Outputs().Tag(kTrackingChunkTag).Set<TrackingDataChunk>();
   }
-  if (cc->Outputs().HasTag("COMPLETE")) {
+  if (cc->Outputs().HasTag(kCompleteTag)) {
-    cc->Outputs().Tag("COMPLETE").Set<bool>();
+    cc->Outputs().Tag(kCompleteTag).Set<bool>();
   }
 
-  if (cc->InputSidePackets().HasTag("CACHE_DIR")) {
+  if (cc->InputSidePackets().HasTag(kCacheDirTag)) {
-    cc->InputSidePackets().Tag("CACHE_DIR").Set<std::string>();
+    cc->InputSidePackets().Tag(kCacheDirTag).Set<std::string>();
   }
 
   return absl::OkStatus();
@@ -122,24 +129,24 @@ absl::Status FlowPackagerCalculator::Open(CalculatorContext* cc) {
 
   flow_packager_.reset(new FlowPackager(options_.flow_packager_options()));
 
-  use_caching_ = cc->InputSidePackets().HasTag("CACHE_DIR");
+  use_caching_ = cc->InputSidePackets().HasTag(kCacheDirTag);
-  build_chunk_ = use_caching_ || cc->Outputs().HasTag("TRACKING_CHUNK");
+  build_chunk_ = use_caching_ || cc->Outputs().HasTag(kTrackingChunkTag);
   if (use_caching_) {
-    cache_dir_ = cc->InputSidePackets().Tag("CACHE_DIR").Get<std::string>();
+    cache_dir_ = cc->InputSidePackets().Tag(kCacheDirTag).Get<std::string>();
   }
 
   return absl::OkStatus();
 }
 
 absl::Status FlowPackagerCalculator::Process(CalculatorContext* cc) {
-  InputStream* flow_stream = &(cc->Inputs().Tag("FLOW"));
+  InputStream* flow_stream = &(cc->Inputs().Tag(kFlowTag));
   const RegionFlowFeatureList& flow = flow_stream->Get<RegionFlowFeatureList>();
 
   const Timestamp timestamp = flow_stream->Value().Timestamp();
 
   const CameraMotion* camera_motion = nullptr;
-  if (cc->Inputs().HasTag("CAMERA")) {
+  if (cc->Inputs().HasTag(kCameraTag)) {
-    InputStream* camera_stream = &(cc->Inputs().Tag("CAMERA"));
+    InputStream* camera_stream = &(cc->Inputs().Tag(kCameraTag));
     camera_motion = &camera_stream->Get<CameraMotion>();
   }
 
@@ -161,7 +168,7 @@ absl::Status FlowPackagerCalculator::Process(CalculatorContext* cc) {
     if (frame_idx_ > 0) {
       item->set_prev_timestamp_usec(prev_timestamp_.Value());
     }
-    if (cc->Outputs().HasTag("TRACKING")) {
+    if (cc->Outputs().HasTag(kTrackingTag)) {
       // Need to copy as output is requested.
       *item->mutable_tracking_data() = *tracking_data;
     } else {
@@ -172,9 +179,9 @@ absl::Status FlowPackagerCalculator::Process(CalculatorContext* cc) {
         options_.caching_chunk_size_msec() * (chunk_idx_ + 1);
 
     if (timestamp.Value() / 1000 >= next_chunk_msec) {
-      if (cc->Outputs().HasTag("TRACKING_CHUNK")) {
+      if (cc->Outputs().HasTag(kTrackingChunkTag)) {
         cc->Outputs()
-            .Tag("TRACKING_CHUNK")
+            .Tag(kTrackingChunkTag)
             .Add(new TrackingDataChunk(tracking_chunk_),
                  Timestamp(tracking_chunk_.item(0).timestamp_usec()));
       }
@@ -185,9 +192,9 @@ absl::Status FlowPackagerCalculator::Process(CalculatorContext* cc) {
     }
   }
 
-  if (cc->Outputs().HasTag("TRACKING")) {
+  if (cc->Outputs().HasTag(kTrackingTag)) {
     cc->Outputs()
-        .Tag("TRACKING")
+        .Tag(kTrackingTag)
         .Add(tracking_data.release(), flow_stream->Value().Timestamp());
   }
 
@@ -199,9 +206,9 @@ absl::Status FlowPackagerCalculator::Process(CalculatorContext* cc) {
 absl::Status FlowPackagerCalculator::Close(CalculatorContext* cc) {
   if (frame_idx_ > 0) {
     tracking_chunk_.set_last_chunk(true);
-    if (cc->Outputs().HasTag("TRACKING_CHUNK")) {
+    if (cc->Outputs().HasTag(kTrackingChunkTag)) {
       cc->Outputs()
-          .Tag("TRACKING_CHUNK")
+          .Tag(kTrackingChunkTag)
           .Add(new TrackingDataChunk(tracking_chunk_),
                Timestamp(tracking_chunk_.item(0).timestamp_usec()));
     }
@@ -211,8 +218,8 @@ absl::Status FlowPackagerCalculator::Close(CalculatorContext* cc) {
     }
   }
 
-  if (cc->Outputs().HasTag("COMPLETE")) {
+  if (cc->Outputs().HasTag(kCompleteTag)) {
-    cc->Outputs().Tag("COMPLETE").Add(new bool(true), Timestamp::PreStream());
+    cc->Outputs().Tag(kCompleteTag).Add(new bool(true), Timestamp::PreStream());
   }
 
   return absl::OkStatus();

mediapipe/calculators/video/motion_analysis_calculator.cc

@@ -38,6 +38,18 @@
 
 namespace mediapipe {
 
+constexpr char kDownsampleTag[] = "DOWNSAMPLE";
+constexpr char kCsvFileTag[] = "CSV_FILE";
+constexpr char kGrayVideoOutTag[] = "GRAY_VIDEO_OUT";
+constexpr char kVideoOutTag[] = "VIDEO_OUT";
+constexpr char kDenseFgTag[] = "DENSE_FG";
+constexpr char kVizTag[] = "VIZ";
+constexpr char kSaliencyTag[] = "SALIENCY";
+constexpr char kCameraTag[] = "CAMERA";
+constexpr char kFlowTag[] = "FLOW";
+constexpr char kSelectionTag[] = "SELECTION";
+constexpr char kVideoTag[] = "VIDEO";
+
 using mediapipe::AffineAdapter;
 using mediapipe::CameraMotion;
 using mediapipe::FrameSelectionResult;
@@ -190,55 +202,56 @@ class MotionAnalysisCalculator : public CalculatorBase {
 REGISTER_CALCULATOR(MotionAnalysisCalculator);
 
 absl::Status MotionAnalysisCalculator::GetContract(CalculatorContract* cc) {
-  if (cc->Inputs().HasTag("VIDEO")) {
+  if (cc->Inputs().HasTag(kVideoTag)) {
-    cc->Inputs().Tag("VIDEO").Set<ImageFrame>();
+    cc->Inputs().Tag(kVideoTag).Set<ImageFrame>();
   }
 
   // Optional input stream from frame selection calculator.
-  if (cc->Inputs().HasTag("SELECTION")) {
+  if (cc->Inputs().HasTag(kSelectionTag)) {
-    cc->Inputs().Tag("SELECTION").Set<FrameSelectionResult>();
+    cc->Inputs().Tag(kSelectionTag).Set<FrameSelectionResult>();
   }
 
-  RET_CHECK(cc->Inputs().HasTag("VIDEO") || cc->Inputs().HasTag("SELECTION"))
+  RET_CHECK(cc->Inputs().HasTag(kVideoTag) ||
+            cc->Inputs().HasTag(kSelectionTag))
       << "Either VIDEO, SELECTION must be specified.";
 
-  if (cc->Outputs().HasTag("FLOW")) {
+  if (cc->Outputs().HasTag(kFlowTag)) {
-    cc->Outputs().Tag("FLOW").Set<RegionFlowFeatureList>();
+    cc->Outputs().Tag(kFlowTag).Set<RegionFlowFeatureList>();
   }
 
-  if (cc->Outputs().HasTag("CAMERA")) {
+  if (cc->Outputs().HasTag(kCameraTag)) {
-    cc->Outputs().Tag("CAMERA").Set<CameraMotion>();
+    cc->Outputs().Tag(kCameraTag).Set<CameraMotion>();
   }
 
-  if (cc->Outputs().HasTag("SALIENCY")) {
+  if (cc->Outputs().HasTag(kSaliencyTag)) {
-    cc->Outputs().Tag("SALIENCY").Set<SalientPointFrame>();
+    cc->Outputs().Tag(kSaliencyTag).Set<SalientPointFrame>();
   }
 
-  if (cc->Outputs().HasTag("VIZ")) {
+  if (cc->Outputs().HasTag(kVizTag)) {
-    cc->Outputs().Tag("VIZ").Set<ImageFrame>();
+    cc->Outputs().Tag(kVizTag).Set<ImageFrame>();
   }
 
-  if (cc->Outputs().HasTag("DENSE_FG")) {
+  if (cc->Outputs().HasTag(kDenseFgTag)) {
-    cc->Outputs().Tag("DENSE_FG").Set<ImageFrame>();
+    cc->Outputs().Tag(kDenseFgTag).Set<ImageFrame>();
   }
 
-  if (cc->Outputs().HasTag("VIDEO_OUT")) {
+  if (cc->Outputs().HasTag(kVideoOutTag)) {
-    cc->Outputs().Tag("VIDEO_OUT").Set<ImageFrame>();
+    cc->Outputs().Tag(kVideoOutTag).Set<ImageFrame>();
   }
 
-  if (cc->Outputs().HasTag("GRAY_VIDEO_OUT")) {
+  if (cc->Outputs().HasTag(kGrayVideoOutTag)) {
     // We only output grayscale video if we're actually performing full region-
     // flow analysis on the video.
-    RET_CHECK(cc->Inputs().HasTag("VIDEO") &&
+    RET_CHECK(cc->Inputs().HasTag(kVideoTag) &&
-              !cc->Inputs().HasTag("SELECTION"));
+              !cc->Inputs().HasTag(kSelectionTag));
-    cc->Outputs().Tag("GRAY_VIDEO_OUT").Set<ImageFrame>();
+    cc->Outputs().Tag(kGrayVideoOutTag).Set<ImageFrame>();
   }
 
-  if (cc->InputSidePackets().HasTag("CSV_FILE")) {
+  if (cc->InputSidePackets().HasTag(kCsvFileTag)) {
-    cc->InputSidePackets().Tag("CSV_FILE").Set<std::string>();
+    cc->InputSidePackets().Tag(kCsvFileTag).Set<std::string>();
   }
-  if (cc->InputSidePackets().HasTag("DOWNSAMPLE")) {
+  if (cc->InputSidePackets().HasTag(kDownsampleTag)) {
-    cc->InputSidePackets().Tag("DOWNSAMPLE").Set<float>();
+    cc->InputSidePackets().Tag(kDownsampleTag).Set<float>();
   }
 
   if (cc->InputSidePackets().HasTag(kOptionsTag)) {
@@ -253,16 +266,16 @@ absl::Status MotionAnalysisCalculator::Open(CalculatorContext* cc) {
       tool::RetrieveOptions(cc->Options<MotionAnalysisCalculatorOptions>(),
                             cc->InputSidePackets(), kOptionsTag);
 
-  video_input_ = cc->Inputs().HasTag("VIDEO");
+  video_input_ = cc->Inputs().HasTag(kVideoTag);
-  selection_input_ = cc->Inputs().HasTag("SELECTION");
+  selection_input_ = cc->Inputs().HasTag(kSelectionTag);
-  region_flow_feature_output_ = cc->Outputs().HasTag("FLOW");
+  region_flow_feature_output_ = cc->Outputs().HasTag(kFlowTag);
-  camera_motion_output_ = cc->Outputs().HasTag("CAMERA");
+  camera_motion_output_ = cc->Outputs().HasTag(kCameraTag);
-  saliency_output_ = cc->Outputs().HasTag("SALIENCY");
+  saliency_output_ = cc->Outputs().HasTag(kSaliencyTag);
-  visualize_output_ = cc->Outputs().HasTag("VIZ");
+  visualize_output_ = cc->Outputs().HasTag(kVizTag);
-  dense_foreground_output_ = cc->Outputs().HasTag("DENSE_FG");
+  dense_foreground_output_ = cc->Outputs().HasTag(kDenseFgTag);
-  video_output_ = cc->Outputs().HasTag("VIDEO_OUT");
+  video_output_ = cc->Outputs().HasTag(kVideoOutTag);
-  grayscale_output_ = cc->Outputs().HasTag("GRAY_VIDEO_OUT");
+  grayscale_output_ = cc->Outputs().HasTag(kGrayVideoOutTag);
-  csv_file_input_ = cc->InputSidePackets().HasTag("CSV_FILE");
+  csv_file_input_ = cc->InputSidePackets().HasTag(kCsvFileTag);
   hybrid_meta_analysis_ = options_.meta_analysis() ==
                           MotionAnalysisCalculatorOptions::META_ANALYSIS_HYBRID;
 
@@ -310,7 +323,7 @@ absl::Status MotionAnalysisCalculator::Open(CalculatorContext* cc) {
   if (csv_file_input_) {
     // Read from file and parse.
     const std::string filename =
-        cc->InputSidePackets().Tag("CSV_FILE").Get<std::string>();
+        cc->InputSidePackets().Tag(kCsvFileTag).Get<std::string>();
 
     std::string file_contents;
     std::ifstream input_file(filename, std::ios::in);
@@ -327,11 +340,12 @@ absl::Status MotionAnalysisCalculator::Open(CalculatorContext* cc) {
 
   // Get video header from video or selection input if present.
   const VideoHeader* video_header = nullptr;
-  if (video_input_ && !cc->Inputs().Tag("VIDEO").Header().IsEmpty()) {
+  if (video_input_ && !cc->Inputs().Tag(kVideoTag).Header().IsEmpty()) {
-    video_header = &(cc->Inputs().Tag("VIDEO").Header().Get<VideoHeader>());
+    video_header = &(cc->Inputs().Tag(kVideoTag).Header().Get<VideoHeader>());
   } else if (selection_input_ &&
-             !cc->Inputs().Tag("SELECTION").Header().IsEmpty()) {
+             !cc->Inputs().Tag(kSelectionTag).Header().IsEmpty()) {
-    video_header = &(cc->Inputs().Tag("SELECTION").Header().Get<VideoHeader>());
+    video_header =
+        &(cc->Inputs().Tag(kSelectionTag).Header().Get<VideoHeader>());
   } else {
     LOG(WARNING) << "No input video header found. Downstream calculators "
                     "expecting video headers are likely to fail.";
@@ -339,7 +353,7 @@ absl::Status MotionAnalysisCalculator::Open(CalculatorContext* cc) {
 
   with_saliency_ = options_.analysis_options().compute_motion_saliency();
   // Force computation of saliency if requested as output.
-  if (cc->Outputs().HasTag("SALIENCY")) {
+  if (cc->Outputs().HasTag(kSaliencyTag)) {
     with_saliency_ = true;
     if (!options_.analysis_options().compute_motion_saliency()) {
       LOG(WARNING) << "Enable saliency computation. Set "
@@ -353,11 +367,11 @@ absl::Status MotionAnalysisCalculator::Open(CalculatorContext* cc) {
     cc->SetOffset(TimestampDiff(0));
   }
 
-  if (cc->InputSidePackets().HasTag("DOWNSAMPLE")) {
+  if (cc->InputSidePackets().HasTag(kDownsampleTag)) {
     options_.mutable_analysis_options()
         ->mutable_flow_options()
         ->set_downsample_factor(
-            cc->InputSidePackets().Tag("DOWNSAMPLE").Get<float>());
+            cc->InputSidePackets().Tag(kDownsampleTag).Get<float>());
   }
 
   // If no video header is provided, just return and initialize on the first
@@ -369,30 +383,33 @@ absl::Status MotionAnalysisCalculator::Open(CalculatorContext* cc) {
   ////////////// EARLY RETURN; ONLY HEADER OUTPUT SHOULD GO HERE ///////////////
 
   if (visualize_output_) {
-    cc->Outputs().Tag("VIZ").SetHeader(Adopt(new VideoHeader(*video_header)));
+    cc->Outputs().Tag(kVizTag).SetHeader(Adopt(new VideoHeader(*video_header)));
   }
 
   if (video_output_) {
     cc->Outputs()
-        .Tag("VIDEO_OUT")
+        .Tag(kVideoOutTag)
         .SetHeader(Adopt(new VideoHeader(*video_header)));
   }
 
-  if (cc->Outputs().HasTag("DENSE_FG")) {
+  if (cc->Outputs().HasTag(kDenseFgTag)) {
     std::unique_ptr<VideoHeader> foreground_header(
         new VideoHeader(*video_header));
     foreground_header->format = ImageFormat::GRAY8;
-    cc->Outputs().Tag("DENSE_FG").SetHeader(Adopt(foreground_header.release()));
-  }
-
-  if (cc->Outputs().HasTag("CAMERA")) {
-    cc->Outputs().Tag("CAMERA").SetHeader(
-        Adopt(new VideoHeader(*video_header)));
-  }
-
-  if (cc->Outputs().HasTag("SALIENCY")) {
     cc->Outputs()
-        .Tag("SALIENCY")
+        .Tag(kDenseFgTag)
+        .SetHeader(Adopt(foreground_header.release()));
+  }
+
+  if (cc->Outputs().HasTag(kCameraTag)) {
+    cc->Outputs()
+        .Tag(kCameraTag)
+        .SetHeader(Adopt(new VideoHeader(*video_header)));
+  }
+
+  if (cc->Outputs().HasTag(kSaliencyTag)) {
+    cc->Outputs()
+        .Tag(kSaliencyTag)
         .SetHeader(Adopt(new VideoHeader(*video_header)));
   }
 
@@ -405,9 +422,9 @@ absl::Status MotionAnalysisCalculator::Process(CalculatorContext* cc) {
   }
 
   InputStream* video_stream =
-      video_input_ ? &(cc->Inputs().Tag("VIDEO")) : nullptr;
+      video_input_ ? &(cc->Inputs().Tag(kVideoTag)) : nullptr;
   InputStream* selection_stream =
-      selection_input_ ? &(cc->Inputs().Tag("SELECTION")) : nullptr;
+      selection_input_ ? &(cc->Inputs().Tag(kSelectionTag)) : nullptr;
 
   // Checked on Open.
   CHECK(video_stream || selection_stream);
@@ -425,8 +442,9 @@ absl::Status MotionAnalysisCalculator::Process(CalculatorContext* cc) {
       CameraMotion output_motion = meta_motions_.front();
       meta_motions_.pop_front();
       output_motion.set_timestamp_usec(timestamp.Value());
-      cc->Outputs().Tag("CAMERA").Add(new CameraMotion(output_motion),
+      cc->Outputs()
-                                      timestamp);
+          .Tag(kCameraTag)
+          .Add(new CameraMotion(output_motion), timestamp);
     }
 
     if (region_flow_feature_output_) {
@@ -435,8 +453,8 @@ absl::Status MotionAnalysisCalculator::Process(CalculatorContext* cc) {
       meta_features_.pop_front();
 
       output_features.set_timestamp_usec(timestamp.Value());
-      cc->Outputs().Tag("FLOW").Add(new RegionFlowFeatureList(output_features),
+      cc->Outputs().Tag(kFlowTag).Add(
-                                    timestamp);
+          new RegionFlowFeatureList(output_features), timestamp);
     }
 
     ++frame_idx_;
@@ -478,16 +496,17 @@ absl::Status MotionAnalysisCalculator::Process(CalculatorContext* cc) {
           MotionAnalysisCalculatorOptions::NO_ANALYSIS_USE_SELECTION) {
     // Output concatenated results, nothing to compute here.
     if (camera_motion_output_) {
-      cc->Outputs().Tag("CAMERA").Add(
+      cc->Outputs()
-          frame_selection_result->release_camera_motion(), timestamp);
+          .Tag(kCameraTag)
+          .Add(frame_selection_result->release_camera_motion(), timestamp);
     }
     if (region_flow_feature_output_) {
-      cc->Outputs().Tag("FLOW").Add(frame_selection_result->release_features(),
+      cc->Outputs().Tag(kFlowTag).Add(
-                                    timestamp);
+          frame_selection_result->release_features(), timestamp);
     }
 
     if (video_output_) {
-      cc->Outputs().Tag("VIDEO_OUT").AddPacket(video_stream->Value());
+      cc->Outputs().Tag(kVideoOutTag).AddPacket(video_stream->Value());
     }
 
     return absl::OkStatus();
@@ -565,7 +584,7 @@ absl::Status MotionAnalysisCalculator::Process(CalculatorContext* cc) {
       grayscale_mat.copyTo(image_frame_mat);
 
       cc->Outputs()
-          .Tag("GRAY_VIDEO_OUT")
+          .Tag(kGrayVideoOutTag)
           .Add(grayscale_image.release(), timestamp);
     }
 
@@ -640,7 +659,7 @@ void MotionAnalysisCalculator::OutputMotionAnalyzedFrames(
           *feature_list, *camera_motion,
           with_saliency_ ? saliency[k].get() : nullptr, &visualization);
 
-      cc->Outputs().Tag("VIZ").Add(visualization_frame.release(), timestamp);
+      cc->Outputs().Tag(kVizTag).Add(visualization_frame.release(), timestamp);
     }
 
     // Output dense foreground mask.
@@ -650,26 +669,26 @@ void MotionAnalysisCalculator::OutputMotionAnalyzedFrames(
       cv::Mat foreground = formats::MatView(foreground_frame.get());
       motion_analysis_->ComputeDenseForeground(*feature_list, *camera_motion,
                                                &foreground);
-      cc->Outputs().Tag("DENSE_FG").Add(foreground_frame.release(), timestamp);
+      cc->Outputs().Tag(kDenseFgTag).Add(foreground_frame.release(), timestamp);
     }
 
     // Output flow features if requested.
     if (region_flow_feature_output_) {
-      cc->Outputs().Tag("FLOW").Add(feature_list.release(), timestamp);
+      cc->Outputs().Tag(kFlowTag).Add(feature_list.release(), timestamp);
     }
 
     // Output camera motion.
     if (camera_motion_output_) {
-      cc->Outputs().Tag("CAMERA").Add(camera_motion.release(), timestamp);
+      cc->Outputs().Tag(kCameraTag).Add(camera_motion.release(), timestamp);
     }
 
     if (video_output_) {
-      cc->Outputs().Tag("VIDEO_OUT").AddPacket(packet_buffer_[k]);
+      cc->Outputs().Tag(kVideoOutTag).AddPacket(packet_buffer_[k]);
     }
 
     // Output saliency.
     if (saliency_output_) {
-      cc->Outputs().Tag("SALIENCY").Add(saliency[k].release(), timestamp);
+      cc->Outputs().Tag(kSaliencyTag).Add(saliency[k].release(), timestamp);
     }
   }
 

mediapipe/calculators/video/opencv_video_decoder_calculator.cc

@@ -27,6 +27,12 @@
 namespace mediapipe {
 
 namespace {
+
+constexpr char kSavedAudioPathTag[] = "SAVED_AUDIO_PATH";
+constexpr char kVideoPrestreamTag[] = "VIDEO_PRESTREAM";
+constexpr char kVideoTag[] = "VIDEO";
+constexpr char kInputFilePathTag[] = "INPUT_FILE_PATH";
+
 // cv::VideoCapture set data type to unsigned char by default. Therefore, the
 // image format is only related to the number of channles the cv::Mat has.
 ImageFormat::Format GetImageFormat(int num_channels) {
@@ -87,20 +93,20 @@ ImageFormat::Format GetImageFormat(int num_channels) {
 class OpenCvVideoDecoderCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->InputSidePackets().Tag("INPUT_FILE_PATH").Set<std::string>();
+    cc->InputSidePackets().Tag(kInputFilePathTag).Set<std::string>();
-    cc->Outputs().Tag("VIDEO").Set<ImageFrame>();
+    cc->Outputs().Tag(kVideoTag).Set<ImageFrame>();
-    if (cc->Outputs().HasTag("VIDEO_PRESTREAM")) {
+    if (cc->Outputs().HasTag(kVideoPrestreamTag)) {
-      cc->Outputs().Tag("VIDEO_PRESTREAM").Set<VideoHeader>();
+      cc->Outputs().Tag(kVideoPrestreamTag).Set<VideoHeader>();
     }
-    if (cc->OutputSidePackets().HasTag("SAVED_AUDIO_PATH")) {
+    if (cc->OutputSidePackets().HasTag(kSavedAudioPathTag)) {
-      cc->OutputSidePackets().Tag("SAVED_AUDIO_PATH").Set<std::string>();
+      cc->OutputSidePackets().Tag(kSavedAudioPathTag).Set<std::string>();
     }
     return absl::OkStatus();
   }
 
   absl::Status Open(CalculatorContext* cc) override {
     const std::string& input_file_path =
-        cc->InputSidePackets().Tag("INPUT_FILE_PATH").Get<std::string>();
+        cc->InputSidePackets().Tag(kInputFilePathTag).Get<std::string>();
     cap_ = absl::make_unique<cv::VideoCapture>(input_file_path);
     if (!cap_->isOpened()) {
       return mediapipe::InvalidArgumentErrorBuilder(MEDIAPIPE_LOC)
@@ -140,16 +146,16 @@ class OpenCvVideoDecoderCalculator : public CalculatorBase {
     header->frame_rate = fps;
     header->duration = frame_count_ / fps;
 
-    if (cc->Outputs().HasTag("VIDEO_PRESTREAM")) {
+    if (cc->Outputs().HasTag(kVideoPrestreamTag)) {
       cc->Outputs()
-          .Tag("VIDEO_PRESTREAM")
+          .Tag(kVideoPrestreamTag)
           .Add(header.release(), Timestamp::PreStream());
-      cc->Outputs().Tag("VIDEO_PRESTREAM").Close();
+      cc->Outputs().Tag(kVideoPrestreamTag).Close();
     }
     // Rewind to the very first frame.
     cap_->set(cv::CAP_PROP_POS_AVI_RATIO, 0);
 
-    if (cc->OutputSidePackets().HasTag("SAVED_AUDIO_PATH")) {
+    if (cc->OutputSidePackets().HasTag(kSavedAudioPathTag)) {
 #ifdef HAVE_FFMPEG
       std::string saved_audio_path = std::tmpnam(nullptr);
       std::string ffmpeg_command =
@@ -159,14 +165,14 @@ class OpenCvVideoDecoderCalculator : public CalculatorBase {
       int status_code = system(absl::StrCat("ls ", saved_audio_path).c_str());
       if (status_code == 0) {
         cc->OutputSidePackets()
-            .Tag("SAVED_AUDIO_PATH")
+            .Tag(kSavedAudioPathTag)
             .Set(MakePacket<std::string>(saved_audio_path));
       } else {
         LOG(WARNING) << "FFmpeg can't extract audio from " << input_file_path
                      << " by executing the following command: "
                      << ffmpeg_command;
         cc->OutputSidePackets()
-            .Tag("SAVED_AUDIO_PATH")
+            .Tag(kSavedAudioPathTag)
             .Set(MakePacket<std::string>(std::string()));
       }
 #else
@@ -208,7 +214,7 @@ class OpenCvVideoDecoderCalculator : public CalculatorBase {
     // If the timestamp of the current frame is not greater than the one of the
     // previous frame, the new frame will be discarded.
     if (prev_timestamp_ < timestamp) {
-      cc->Outputs().Tag("VIDEO").Add(image_frame.release(), timestamp);
+      cc->Outputs().Tag(kVideoTag).Add(image_frame.release(), timestamp);
       prev_timestamp_ = timestamp;
       decoded_frames_++;
     }

mediapipe/calculators/video/opencv_video_decoder_calculator_test.cc

@@ -29,6 +29,10 @@ namespace mediapipe {
 
 namespace {
 
+constexpr char kVideoTag[] = "VIDEO";
+constexpr char kVideoPrestreamTag[] = "VIDEO_PRESTREAM";
+constexpr char kInputFilePathTag[] = "INPUT_FILE_PATH";
+
 TEST(OpenCvVideoDecoderCalculatorTest, TestMp4Avc720pVideo) {
   CalculatorGraphConfig::Node node_config =
       ParseTextProtoOrDie<CalculatorGraphConfig::Node>(R"pb(
@@ -37,19 +41,19 @@ TEST(OpenCvVideoDecoderCalculatorTest, TestMp4Avc720pVideo) {
         output_stream: "VIDEO:video"
         output_stream: "VIDEO_PRESTREAM:video_prestream")pb");
   CalculatorRunner runner(node_config);
-  runner.MutableSidePackets()->Tag("INPUT_FILE_PATH") = MakePacket<std::string>(
+  runner.MutableSidePackets()->Tag(kInputFilePathTag) = MakePacket<std::string>(
       file::JoinPath("./",
                      "/mediapipe/calculators/video/"
                      "testdata/format_MP4_AVC720P_AAC.video"));
   MP_EXPECT_OK(runner.Run());
 
-  EXPECT_EQ(runner.Outputs().Tag("VIDEO_PRESTREAM").packets.size(), 1);
+  EXPECT_EQ(runner.Outputs().Tag(kVideoPrestreamTag).packets.size(), 1);
   MP_EXPECT_OK(runner.Outputs()
-                   .Tag("VIDEO_PRESTREAM")
+                   .Tag(kVideoPrestreamTag)
                    .packets[0]
                    .ValidateAsType<VideoHeader>());
   const mediapipe::VideoHeader& header =
-      runner.Outputs().Tag("VIDEO_PRESTREAM").packets[0].Get<VideoHeader>();
+      runner.Outputs().Tag(kVideoPrestreamTag).packets[0].Get<VideoHeader>();
   EXPECT_EQ(ImageFormat::SRGB, header.format);
   EXPECT_EQ(1280, header.width);
   EXPECT_EQ(640, header.height);
@@ -58,10 +62,10 @@ TEST(OpenCvVideoDecoderCalculatorTest, TestMp4Avc720pVideo) {
   // The number of the output packets should be 180.
   // Some OpenCV version returns the first two frames with the same timestamp on
   // macos and we might miss one frame here.
-  int num_of_packets = runner.Outputs().Tag("VIDEO").packets.size();
+  int num_of_packets = runner.Outputs().Tag(kVideoTag).packets.size();
   EXPECT_GE(num_of_packets, 179);
   for (int i = 0; i < num_of_packets; ++i) {
-    Packet image_frame_packet = runner.Outputs().Tag("VIDEO").packets[i];
+    Packet image_frame_packet = runner.Outputs().Tag(kVideoTag).packets[i];
     cv::Mat output_mat =
         formats::MatView(&(image_frame_packet.Get<ImageFrame>()));
     EXPECT_EQ(1280, output_mat.size().width);
@@ -83,19 +87,19 @@ TEST(OpenCvVideoDecoderCalculatorTest, TestFlvH264Video) {
         output_stream: "VIDEO:video"
         output_stream: "VIDEO_PRESTREAM:video_prestream")pb");
   CalculatorRunner runner(node_config);
-  runner.MutableSidePackets()->Tag("INPUT_FILE_PATH") = MakePacket<std::string>(
+  runner.MutableSidePackets()->Tag(kInputFilePathTag) = MakePacket<std::string>(
       file::JoinPath("./",
                      "/mediapipe/calculators/video/"
                      "testdata/format_FLV_H264_AAC.video"));
   MP_EXPECT_OK(runner.Run());
 
-  EXPECT_EQ(runner.Outputs().Tag("VIDEO_PRESTREAM").packets.size(), 1);
+  EXPECT_EQ(runner.Outputs().Tag(kVideoPrestreamTag).packets.size(), 1);
   MP_EXPECT_OK(runner.Outputs()
-                   .Tag("VIDEO_PRESTREAM")
+                   .Tag(kVideoPrestreamTag)
                    .packets[0]
                    .ValidateAsType<VideoHeader>());
   const mediapipe::VideoHeader& header =
-      runner.Outputs().Tag("VIDEO_PRESTREAM").packets[0].Get<VideoHeader>();
+      runner.Outputs().Tag(kVideoPrestreamTag).packets[0].Get<VideoHeader>();
   EXPECT_EQ(ImageFormat::SRGB, header.format);
   EXPECT_EQ(640, header.width);
   EXPECT_EQ(320, header.height);
@@ -103,9 +107,9 @@ TEST(OpenCvVideoDecoderCalculatorTest, TestFlvH264Video) {
   // can be either 30.30303f (with opencv2) or 30f (with opencv3 and opencv4).
   // EXPECT_FLOAT_EQ(6.0f, header.duration);
   // EXPECT_FLOAT_EQ(30.0f, header.frame_rate);
-  EXPECT_EQ(180, runner.Outputs().Tag("VIDEO").packets.size());
+  EXPECT_EQ(180, runner.Outputs().Tag(kVideoTag).packets.size());
   for (int i = 0; i < 180; ++i) {
-    Packet image_frame_packet = runner.Outputs().Tag("VIDEO").packets[i];
+    Packet image_frame_packet = runner.Outputs().Tag(kVideoTag).packets[i];
     cv::Mat output_mat =
         formats::MatView(&(image_frame_packet.Get<ImageFrame>()));
     EXPECT_EQ(640, output_mat.size().width);
@@ -127,19 +131,19 @@ TEST(OpenCvVideoDecoderCalculatorTest, TestMkvVp8Video) {
         output_stream: "VIDEO:video"
         output_stream: "VIDEO_PRESTREAM:video_prestream")pb");
   CalculatorRunner runner(node_config);
-  runner.MutableSidePackets()->Tag("INPUT_FILE_PATH") = MakePacket<std::string>(
+  runner.MutableSidePackets()->Tag(kInputFilePathTag) = MakePacket<std::string>(
       file::JoinPath("./",
                      "/mediapipe/calculators/video/"
                      "testdata/format_MKV_VP8_VORBIS.video"));
   MP_EXPECT_OK(runner.Run());
 
-  EXPECT_EQ(runner.Outputs().Tag("VIDEO_PRESTREAM").packets.size(), 1);
+  EXPECT_EQ(runner.Outputs().Tag(kVideoPrestreamTag).packets.size(), 1);
   MP_EXPECT_OK(runner.Outputs()
-                   .Tag("VIDEO_PRESTREAM")
+                   .Tag(kVideoPrestreamTag)
                    .packets[0]
                    .ValidateAsType<VideoHeader>());
   const mediapipe::VideoHeader& header =
-      runner.Outputs().Tag("VIDEO_PRESTREAM").packets[0].Get<VideoHeader>();
+      runner.Outputs().Tag(kVideoPrestreamTag).packets[0].Get<VideoHeader>();
   EXPECT_EQ(ImageFormat::SRGB, header.format);
   EXPECT_EQ(640, header.width);
   EXPECT_EQ(320, header.height);
@@ -148,10 +152,10 @@ TEST(OpenCvVideoDecoderCalculatorTest, TestMkvVp8Video) {
   // The number of the output packets should be 180.
   // Some OpenCV version returns the first two frames with the same timestamp on
   // macos and we might miss one frame here.
-  int num_of_packets = runner.Outputs().Tag("VIDEO").packets.size();
+  int num_of_packets = runner.Outputs().Tag(kVideoTag).packets.size();
   EXPECT_GE(num_of_packets, 179);
   for (int i = 0; i < num_of_packets; ++i) {
-    Packet image_frame_packet = runner.Outputs().Tag("VIDEO").packets[i];
+    Packet image_frame_packet = runner.Outputs().Tag(kVideoTag).packets[i];
     cv::Mat output_mat =
         formats::MatView(&(image_frame_packet.Get<ImageFrame>()));
     EXPECT_EQ(640, output_mat.size().width);

mediapipe/calculators/video/opencv_video_encoder_calculator.cc

@@ -36,6 +36,11 @@
 
 namespace mediapipe {
 
+constexpr char kAudioFilePathTag[] = "AUDIO_FILE_PATH";
+constexpr char kOutputFilePathTag[] = "OUTPUT_FILE_PATH";
+constexpr char kVideoPrestreamTag[] = "VIDEO_PRESTREAM";
+constexpr char kVideoTag[] = "VIDEO";
+
 // Encodes the input video stream and produces a media file.
 // The media file can be output to the output_file_path specified as a side
 // packet. Currently, the calculator only supports one video stream (in
@@ -90,15 +95,15 @@ class OpenCvVideoEncoderCalculator : public CalculatorBase {
 };
 
 absl::Status OpenCvVideoEncoderCalculator::GetContract(CalculatorContract* cc) {
-  RET_CHECK(cc->Inputs().HasTag("VIDEO"));
+  RET_CHECK(cc->Inputs().HasTag(kVideoTag));
-  cc->Inputs().Tag("VIDEO").Set<ImageFrame>();
+  cc->Inputs().Tag(kVideoTag).Set<ImageFrame>();
-  if (cc->Inputs().HasTag("VIDEO_PRESTREAM")) {
+  if (cc->Inputs().HasTag(kVideoPrestreamTag)) {
-    cc->Inputs().Tag("VIDEO_PRESTREAM").Set<VideoHeader>();
+    cc->Inputs().Tag(kVideoPrestreamTag).Set<VideoHeader>();
   }
-  RET_CHECK(cc->InputSidePackets().HasTag("OUTPUT_FILE_PATH"));
+  RET_CHECK(cc->InputSidePackets().HasTag(kOutputFilePathTag));
-  cc->InputSidePackets().Tag("OUTPUT_FILE_PATH").Set<std::string>();
+  cc->InputSidePackets().Tag(kOutputFilePathTag).Set<std::string>();
-  if (cc->InputSidePackets().HasTag("AUDIO_FILE_PATH")) {
+  if (cc->InputSidePackets().HasTag(kAudioFilePathTag)) {
-    cc->InputSidePackets().Tag("AUDIO_FILE_PATH").Set<std::string>();
+    cc->InputSidePackets().Tag(kAudioFilePathTag).Set<std::string>();
   }
   return absl::OkStatus();
 }
@@ -116,7 +121,7 @@ absl::Status OpenCvVideoEncoderCalculator::Open(CalculatorContext* cc) {
       << "Video format must be specified in "
          "OpenCvVideoEncoderCalculatorOptions";
   output_file_path_ =
-      cc->InputSidePackets().Tag("OUTPUT_FILE_PATH").Get<std::string>();
+      cc->InputSidePackets().Tag(kOutputFilePathTag).Get<std::string>();
   std::vector<std::string> splited_file_path =
       absl::StrSplit(output_file_path_, '.');
   RET_CHECK(splited_file_path.size() >= 2 &&
@@ -126,7 +131,7 @@ absl::Status OpenCvVideoEncoderCalculator::Open(CalculatorContext* cc) {
   // If the video header will be available, the video metadata will be fetched
   // from the video header directly. The calculator will receive the video
   // header packet at timestamp prestream.
-  if (cc->Inputs().HasTag("VIDEO_PRESTREAM")) {
+  if (cc->Inputs().HasTag(kVideoPrestreamTag)) {
     return absl::OkStatus();
   }
   return SetUpVideoWriter(options.fps(), options.width(), options.height());
@@ -135,13 +140,13 @@ absl::Status OpenCvVideoEncoderCalculator::Open(CalculatorContext* cc) {
 absl::Status OpenCvVideoEncoderCalculator::Process(CalculatorContext* cc) {
   if (cc->InputTimestamp() == Timestamp::PreStream()) {
     const VideoHeader& video_header =
-        cc->Inputs().Tag("VIDEO_PRESTREAM").Get<VideoHeader>();
+        cc->Inputs().Tag(kVideoPrestreamTag).Get<VideoHeader>();
     return SetUpVideoWriter(video_header.frame_rate, video_header.width,
                             video_header.height);
   }
 
   const ImageFrame& image_frame =
-      cc->Inputs().Tag("VIDEO").Value().Get<ImageFrame>();
+      cc->Inputs().Tag(kVideoTag).Value().Get<ImageFrame>();
   ImageFormat::Format format = image_frame.Format();
   cv::Mat frame;
   if (format == ImageFormat::GRAY8) {
@@ -149,7 +154,7 @@ absl::Status OpenCvVideoEncoderCalculator::Process(CalculatorContext* cc) {
     if (frame.empty()) {
       return mediapipe::InvalidArgumentErrorBuilder(MEDIAPIPE_LOC)
              << "Receive empty frame at timestamp "
-             << cc->Inputs().Tag("VIDEO").Value().Timestamp()
+             << cc->Inputs().Tag(kVideoTag).Value().Timestamp()
              << " in OpenCvVideoEncoderCalculator::Process()";
     }
   } else {
@@ -157,7 +162,7 @@ absl::Status OpenCvVideoEncoderCalculator::Process(CalculatorContext* cc) {
     if (tmp_frame.empty()) {
       return mediapipe::InvalidArgumentErrorBuilder(MEDIAPIPE_LOC)
              << "Receive empty frame at timestamp "
-             << cc->Inputs().Tag("VIDEO").Value().Timestamp()
+             << cc->Inputs().Tag(kVideoTag).Value().Timestamp()
              << " in OpenCvVideoEncoderCalculator::Process()";
     }
     if (format == ImageFormat::SRGB) {
@@ -177,10 +182,10 @@ absl::Status OpenCvVideoEncoderCalculator::Close(CalculatorContext* cc) {
   if (writer_ && writer_->isOpened()) {
     writer_->release();
   }
-  if (cc->InputSidePackets().HasTag("AUDIO_FILE_PATH")) {
+  if (cc->InputSidePackets().HasTag(kAudioFilePathTag)) {
 #ifdef HAVE_FFMPEG
     const std::string& audio_file_path =
-        cc->InputSidePackets().Tag("AUDIO_FILE_PATH").Get<std::string>();
+        cc->InputSidePackets().Tag(kAudioFilePathTag).Get<std::string>();
     if (audio_file_path.empty()) {
       LOG(WARNING) << "OpenCvVideoEncoderCalculator isn't able to attach the "
                       "audio tracks to the generated video because the audio "

mediapipe/calculators/video/tvl1_optical_flow_calculator.cc

@@ -23,6 +23,11 @@
 namespace mediapipe {
 namespace {
 
+constexpr char kBackwardFlowTag[] = "BACKWARD_FLOW";
+constexpr char kForwardFlowTag[] = "FORWARD_FLOW";
+constexpr char kSecondFrameTag[] = "SECOND_FRAME";
+constexpr char kFirstFrameTag[] = "FIRST_FRAME";
+
 // Checks that img1 and img2 have the same dimensions.
 bool ImageSizesMatch(const ImageFrame& img1, const ImageFrame& img2) {
   return (img1.Width() == img2.Width()) && (img1.Height() == img2.Height());
@@ -94,19 +99,19 @@ class Tvl1OpticalFlowCalculator : public CalculatorBase {
 };
 
 absl::Status Tvl1OpticalFlowCalculator::GetContract(CalculatorContract* cc) {
-  if (!cc->Inputs().HasTag("FIRST_FRAME") ||
+  if (!cc->Inputs().HasTag(kFirstFrameTag) ||
-      !cc->Inputs().HasTag("SECOND_FRAME")) {
+      !cc->Inputs().HasTag(kSecondFrameTag)) {
     return absl::InvalidArgumentError(
         "Missing required input streams. Both FIRST_FRAME and SECOND_FRAME "
         "must be specified.");
   }
-  cc->Inputs().Tag("FIRST_FRAME").Set<ImageFrame>();
+  cc->Inputs().Tag(kFirstFrameTag).Set<ImageFrame>();
-  cc->Inputs().Tag("SECOND_FRAME").Set<ImageFrame>();
+  cc->Inputs().Tag(kSecondFrameTag).Set<ImageFrame>();
-  if (cc->Outputs().HasTag("FORWARD_FLOW")) {
+  if (cc->Outputs().HasTag(kForwardFlowTag)) {
-    cc->Outputs().Tag("FORWARD_FLOW").Set<OpticalFlowField>();
+    cc->Outputs().Tag(kForwardFlowTag).Set<OpticalFlowField>();
   }
-  if (cc->Outputs().HasTag("BACKWARD_FLOW")) {
+  if (cc->Outputs().HasTag(kBackwardFlowTag)) {
-    cc->Outputs().Tag("BACKWARD_FLOW").Set<OpticalFlowField>();
+    cc->Outputs().Tag(kBackwardFlowTag).Set<OpticalFlowField>();
   }
   return absl::OkStatus();
 }
@@ -116,10 +121,10 @@ absl::Status Tvl1OpticalFlowCalculator::Open(CalculatorContext* cc) {
     absl::MutexLock lock(&mutex_);
     tvl1_computers_.emplace_back(cv::createOptFlow_DualTVL1());
   }
-  if (cc->Outputs().HasTag("FORWARD_FLOW")) {
+  if (cc->Outputs().HasTag(kForwardFlowTag)) {
     forward_requested_ = true;
   }
-  if (cc->Outputs().HasTag("BACKWARD_FLOW")) {
+  if (cc->Outputs().HasTag(kBackwardFlowTag)) {
     backward_requested_ = true;
   }
 
@@ -128,15 +133,15 @@ absl::Status Tvl1OpticalFlowCalculator::Open(CalculatorContext* cc) {
 
 absl::Status Tvl1OpticalFlowCalculator::Process(CalculatorContext* cc) {
   const ImageFrame& first_frame =
-      cc->Inputs().Tag("FIRST_FRAME").Value().Get<ImageFrame>();
+      cc->Inputs().Tag(kFirstFrameTag).Value().Get<ImageFrame>();
   const ImageFrame& second_frame =
-      cc->Inputs().Tag("SECOND_FRAME").Value().Get<ImageFrame>();
+      cc->Inputs().Tag(kSecondFrameTag).Value().Get<ImageFrame>();
   if (forward_requested_) {
     auto forward_optical_flow_field = absl::make_unique<OpticalFlowField>();
     MP_RETURN_IF_ERROR(CalculateOpticalFlow(first_frame, second_frame,
                                             forward_optical_flow_field.get()));
     cc->Outputs()
-        .Tag("FORWARD_FLOW")
+        .Tag(kForwardFlowTag)
         .Add(forward_optical_flow_field.release(), cc->InputTimestamp());
   }
   if (backward_requested_) {
@@ -144,7 +149,7 @@ absl::Status Tvl1OpticalFlowCalculator::Process(CalculatorContext* cc) {
     MP_RETURN_IF_ERROR(CalculateOpticalFlow(second_frame, first_frame,
                                             backward_optical_flow_field.get()));
     cc->Outputs()
-        .Tag("BACKWARD_FLOW")
+        .Tag(kBackwardFlowTag)
         .Add(backward_optical_flow_field.release(), cc->InputTimestamp());
   }
   return absl::OkStatus();

mediapipe/calculators/video/video_pre_stream_calculator.cc

@@ -19,6 +19,9 @@
 
 namespace mediapipe {
 
+constexpr char kVideoPrestreamTag[] = "VIDEO_PRESTREAM";
+constexpr char kFrameTag[] = "FRAME";
+
 // Sets up VideoHeader based on the 1st ImageFrame and emits it with timestamp
 // PreStream. Note that this calculator only fills in format, width, and height,
 // i.e. frame_rate and duration will not be filled, unless:
@@ -64,8 +67,8 @@ absl::Status VideoPreStreamCalculator::GetContract(CalculatorContract* cc) {
   if (!cc->Inputs().UsesTags()) {
     cc->Inputs().Index(0).Set<ImageFrame>();
   } else {
-    cc->Inputs().Tag("FRAME").Set<ImageFrame>();
+    cc->Inputs().Tag(kFrameTag).Set<ImageFrame>();
-    cc->Inputs().Tag("VIDEO_PRESTREAM").Set<VideoHeader>();
+    cc->Inputs().Tag(kVideoPrestreamTag).Set<VideoHeader>();
   }
   cc->Outputs().Index(0).Set<VideoHeader>();
   return absl::OkStatus();
@@ -73,8 +76,8 @@ absl::Status VideoPreStreamCalculator::GetContract(CalculatorContract* cc) {
 
 absl::Status VideoPreStreamCalculator::Open(CalculatorContext* cc) {
   frame_rate_in_prestream_ = cc->Inputs().UsesTags() &&
-                             cc->Inputs().HasTag("FRAME") &&
+                             cc->Inputs().HasTag(kFrameTag) &&
-                             cc->Inputs().HasTag("VIDEO_PRESTREAM");
+                             cc->Inputs().HasTag(kVideoPrestreamTag);
   header_ = absl::make_unique<VideoHeader>();
   return absl::OkStatus();
 }
@@ -82,15 +85,15 @@ absl::Status VideoPreStreamCalculator::ProcessWithFrameRateInPreStream(
     CalculatorContext* cc) {
   cc->GetCounter("ProcessWithFrameRateInPreStream")->Increment();
   if (cc->InputTimestamp() == Timestamp::PreStream()) {
-    RET_CHECK(cc->Inputs().Tag("FRAME").IsEmpty());
+    RET_CHECK(cc->Inputs().Tag(kFrameTag).IsEmpty());
-    RET_CHECK(!cc->Inputs().Tag("VIDEO_PRESTREAM").IsEmpty());
+    RET_CHECK(!cc->Inputs().Tag(kVideoPrestreamTag).IsEmpty());
-    *header_ = cc->Inputs().Tag("VIDEO_PRESTREAM").Get<VideoHeader>();
+    *header_ = cc->Inputs().Tag(kVideoPrestreamTag).Get<VideoHeader>();
     RET_CHECK_NE(header_->frame_rate, 0.0) << "frame rate should be non-zero";
   } else {
-    RET_CHECK(cc->Inputs().Tag("VIDEO_PRESTREAM").IsEmpty())
+    RET_CHECK(cc->Inputs().Tag(kVideoPrestreamTag).IsEmpty())
         << "Packet on VIDEO_PRESTREAM must come in at Timestamp::PreStream().";
-    RET_CHECK(!cc->Inputs().Tag("FRAME").IsEmpty());
+    RET_CHECK(!cc->Inputs().Tag(kFrameTag).IsEmpty());
-    const auto& frame = cc->Inputs().Tag("FRAME").Get<ImageFrame>();
+    const auto& frame = cc->Inputs().Tag(kFrameTag).Get<ImageFrame>();
     header_->format = frame.Format();
     header_->width = frame.Width();
     header_->height = frame.Height();

mediapipe/framework/calculator_graph_stopping_test.cc

@@ -44,28 +44,32 @@ using mediapipe::MakePacket;
 using mediapipe::OutputStreamShardSet;
 using mediapipe::Timestamp;
 namespace proto_ns = mediapipe::proto_ns;
+
+constexpr char kEventTag[] = "EVENT";
+constexpr char kOutTag[] = "OUT";
+
 using mediapipe::CalculatorGraph;
 using mediapipe::Packet;
 
 class InfiniteSequenceCalculator : public mediapipe::CalculatorBase {
  public:
   static absl::Status GetContract(mediapipe::CalculatorContract* cc) {
-    cc->Outputs().Tag("OUT").Set<int>();
+    cc->Outputs().Tag(kOutTag).Set<int>();
-    cc->Outputs().Tag("EVENT").Set<int>();
+    cc->Outputs().Tag(kEventTag).Set<int>();
     return absl::OkStatus();
   }
   absl::Status Open(CalculatorContext* cc) override {
-    cc->Outputs().Tag("EVENT").AddPacket(MakePacket<int>(1).At(Timestamp(1)));
+    cc->Outputs().Tag(kEventTag).AddPacket(MakePacket<int>(1).At(Timestamp(1)));
     return absl::OkStatus();
   }
   absl::Status Process(CalculatorContext* cc) override {
-    cc->Outputs().Tag("OUT").AddPacket(
+    cc->Outputs().Tag(kOutTag).AddPacket(
         MakePacket<int>(count_).At(Timestamp(count_)));
     count_++;
     return absl::OkStatus();
   }
   absl::Status Close(CalculatorContext* cc) override {
-    cc->Outputs().Tag("EVENT").AddPacket(MakePacket<int>(2).At(Timestamp(2)));
+    cc->Outputs().Tag(kEventTag).AddPacket(MakePacket<int>(2).At(Timestamp(2)));
     return absl::OkStatus();
   }
 
@@ -81,11 +85,11 @@ class StoppingPassThroughCalculator : public mediapipe::CalculatorBase {
       cc->Inputs().Get("", i).SetAny();
       cc->Outputs().Get("", i).SetSameAs(&cc->Inputs().Get("", i));
     }
-    cc->Outputs().Tag("EVENT").Set<int>();
+    cc->Outputs().Tag(kEventTag).Set<int>();
     return absl::OkStatus();
   }
   absl::Status Open(CalculatorContext* cc) override {
-    cc->Outputs().Tag("EVENT").AddPacket(MakePacket<int>(1).At(Timestamp(1)));
+    cc->Outputs().Tag(kEventTag).AddPacket(MakePacket<int>(1).At(Timestamp(1)));
     return absl::OkStatus();
   }
   absl::Status Process(CalculatorContext* cc) override {
@@ -98,7 +102,7 @@ class StoppingPassThroughCalculator : public mediapipe::CalculatorBase {
                                     : mediapipe::tool::StatusStop();
   }
   absl::Status Close(CalculatorContext* cc) override {
-    cc->Outputs().Tag("EVENT").AddPacket(MakePacket<int>(2).At(Timestamp(2)));
+    cc->Outputs().Tag(kEventTag).AddPacket(MakePacket<int>(2).At(Timestamp(2)));
     return absl::OkStatus();
   }
 

mediapipe/framework/calculator_graph_test.cc

@@ -65,6 +65,16 @@ namespace mediapipe {
 
 namespace {
 
+constexpr char kCounter2Tag[] = "COUNTER2";
+constexpr char kCounter1Tag[] = "COUNTER1";
+constexpr char kExtraTag[] = "EXTRA";
+constexpr char kWaitSemTag[] = "WAIT_SEM";
+constexpr char kPostSemTag[] = "POST_SEM";
+constexpr char kErrorOnOpenTag[] = "ERROR_ON_OPEN";
+constexpr char kOutputTag[] = "OUTPUT";
+constexpr char kInputTag[] = "INPUT";
+constexpr char kSelectTag[] = "SELECT";
+
 using testing::ElementsAre;
 using testing::HasSubstr;
 
@@ -125,8 +135,8 @@ class DemuxTimedCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
     RET_CHECK_EQ(cc->Inputs().NumEntries(), 2);
-    cc->Inputs().Tag("SELECT").Set<int>();
+    cc->Inputs().Tag(kSelectTag).Set<int>();
-    PacketType* data_input = &cc->Inputs().Tag("INPUT");
+    PacketType* data_input = &cc->Inputs().Tag(kInputTag);
     data_input->SetAny();
     for (CollectionItemId id = cc->Outputs().BeginId("OUTPUT");
          id < cc->Outputs().EndId("OUTPUT"); ++id) {
@@ -182,7 +192,7 @@ REGISTER_CALCULATOR(DemuxTimedCalculator);
 class MuxTimedCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->Inputs().Tag("SELECT").Set<int>();
+    cc->Inputs().Tag(kSelectTag).Set<int>();
     CollectionItemId data_input_id = cc->Inputs().BeginId("INPUT");
     PacketType* data_input0 = &cc->Inputs().Get(data_input_id);
     data_input0->SetAny();
@@ -191,7 +201,7 @@ class MuxTimedCalculator : public CalculatorBase {
       cc->Inputs().Get(data_input_id).SetSameAs(data_input0);
     }
     RET_CHECK_EQ(cc->Outputs().NumEntries(), 1);
-    cc->Outputs().Tag("OUTPUT").SetSameAs(data_input0);
+    cc->Outputs().Tag(kOutputTag).SetSameAs(data_input0);
     cc->SetTimestampOffset(TimestampDiff(0));
     return absl::OkStatus();
   }
@@ -598,12 +608,12 @@ class ErrorOnOpenCalculator : public CalculatorBase {
   static absl::Status GetContract(CalculatorContract* cc) {
     cc->Inputs().Index(0).SetAny();
     cc->Outputs().Index(0).SetSameAs(&cc->Inputs().Index(0));
-    cc->InputSidePackets().Tag("ERROR_ON_OPEN").Set<bool>();
+    cc->InputSidePackets().Tag(kErrorOnOpenTag).Set<bool>();
     return absl::OkStatus();
   }
 
   absl::Status Open(CalculatorContext* cc) final {
-    if (cc->InputSidePackets().Tag("ERROR_ON_OPEN").Get<bool>()) {
+    if (cc->InputSidePackets().Tag(kErrorOnOpenTag).Get<bool>()) {
       return absl::NotFoundError("expected error");
     }
     return absl::OkStatus();
@@ -920,8 +930,8 @@ class SemaphoreCalculator : public CalculatorBase {
   static absl::Status GetContract(CalculatorContract* cc) {
     cc->Inputs().Index(0).SetAny();
     cc->Outputs().Index(0).SetSameAs(&cc->Inputs().Index(0));
-    cc->InputSidePackets().Tag("POST_SEM").Set<Semaphore*>();
+    cc->InputSidePackets().Tag(kPostSemTag).Set<Semaphore*>();
-    cc->InputSidePackets().Tag("WAIT_SEM").Set<Semaphore*>();
+    cc->InputSidePackets().Tag(kWaitSemTag).Set<Semaphore*>();
     cc->SetTimestampOffset(TimestampDiff(0));
     return absl::OkStatus();
   }
@@ -929,8 +939,8 @@ class SemaphoreCalculator : public CalculatorBase {
   absl::Status Open(CalculatorContext* cc) override { return absl::OkStatus(); }
 
   absl::Status Process(CalculatorContext* cc) override {
-    cc->InputSidePackets().Tag("POST_SEM").Get<Semaphore*>()->Release(1);
+    cc->InputSidePackets().Tag(kPostSemTag).Get<Semaphore*>()->Release(1);
-    cc->InputSidePackets().Tag("WAIT_SEM").Get<Semaphore*>()->Acquire(1);
+    cc->InputSidePackets().Tag(kWaitSemTag).Get<Semaphore*>()->Acquire(1);
     cc->Outputs().Index(0).AddPacket(cc->Inputs().Index(0).Value());
     return absl::OkStatus();
   }
@@ -1177,9 +1187,9 @@ class IncrementingStatusHandler : public StatusHandler {
   static absl::Status FillExpectations(
       const MediaPipeOptions& extendable_options,
       PacketTypeSet* input_side_packets) {
-    input_side_packets->Tag("EXTRA").SetAny().Optional();
+    input_side_packets->Tag(kExtraTag).SetAny().Optional();
-    input_side_packets->Tag("COUNTER1").Set<std::unique_ptr<int>>();
+    input_side_packets->Tag(kCounter1Tag).Set<std::unique_ptr<int>>();
-    input_side_packets->Tag("COUNTER2").Set<std::unique_ptr<int>>();
+    input_side_packets->Tag(kCounter2Tag).Set<std::unique_ptr<int>>();
     return absl::OkStatus();
   }
 
@@ -1187,7 +1197,7 @@ class IncrementingStatusHandler : public StatusHandler {
       const MediaPipeOptions& extendable_options,
       const PacketSet& input_side_packets,  //
       const absl::Status& pre_run_status) {
-    int* counter = GetFromUniquePtr<int>(input_side_packets.Tag("COUNTER1"));
+    int* counter = GetFromUniquePtr<int>(input_side_packets.Tag(kCounter1Tag));
     (*counter)++;
     return pre_run_status_result_;
   }
@@ -1195,7 +1205,7 @@ class IncrementingStatusHandler : public StatusHandler {
   static absl::Status HandleStatus(const MediaPipeOptions& extendable_options,
                                    const PacketSet& input_side_packets,  //
                                    const absl::Status& run_status) {
-    int* counter = GetFromUniquePtr<int>(input_side_packets.Tag("COUNTER2"));
+    int* counter = GetFromUniquePtr<int>(input_side_packets.Tag(kCounter2Tag));
     (*counter)++;
     return post_run_status_result_;
   }
@@ -2228,20 +2238,20 @@ class DemuxUntimedCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
     RET_CHECK_EQ(cc->Inputs().NumEntries(), 2);
-    cc->Inputs().Tag("INPUT").SetAny();
+    cc->Inputs().Tag(kInputTag).SetAny();
-    cc->Inputs().Tag("SELECT").Set<int>();
+    cc->Inputs().Tag(kSelectTag).Set<int>();
     for (CollectionItemId id = cc->Outputs().BeginId("OUTPUT");
          id < cc->Outputs().EndId("OUTPUT"); ++id) {
-      cc->Outputs().Get(id).SetSameAs(&cc->Inputs().Tag("INPUT"));
+      cc->Outputs().Get(id).SetSameAs(&cc->Inputs().Tag(kInputTag));
     }
     return absl::OkStatus();
   }
   absl::Status Process(CalculatorContext* cc) final {
-    int index = cc->Inputs().Tag("SELECT").Get<int>();
+    int index = cc->Inputs().Tag(kSelectTag).Get<int>();
-    if (!cc->Inputs().Tag("INPUT").IsEmpty()) {
+    if (!cc->Inputs().Tag(kInputTag).IsEmpty()) {
       cc->Outputs()
           .Get("OUTPUT", index)
-          .AddPacket(cc->Inputs().Tag("INPUT").Value());
+          .AddPacket(cc->Inputs().Tag(kInputTag).Value());
     } else {
       cc->Outputs()
           .Get("OUTPUT", index)

mediapipe/framework/calculator_runner_test.cc

@@ -32,6 +32,11 @@
 namespace mediapipe {
 namespace {
 
+constexpr char kTag[] = "";
+constexpr char kBTag[] = "B";
+constexpr char kATag[] = "A";
+constexpr char kSideOutputTag[] = "SIDE_OUTPUT";
+
 // Inputs: 2 streams with ints. Headers are strings.
 // Input side packets: 1.
 // Outputs: 3 streams with ints. #0 and #1 will contain the negated values from
@@ -48,7 +53,7 @@ class CalculatorRunnerTestCalculator : public CalculatorBase {
     cc->Outputs().Index(2).SetSameAs(&cc->InputSidePackets().Index(0));
     cc->InputSidePackets().Index(0).SetAny();
     cc->OutputSidePackets()
-        .Tag("SIDE_OUTPUT")
+        .Tag(kSideOutputTag)
         .SetSameAs(&cc->InputSidePackets().Index(0));
     return absl::OkStatus();
   }
@@ -64,7 +69,7 @@ class CalculatorRunnerTestCalculator : public CalculatorBase {
           Adopt(new std::string(absl::StrCat(input_header_string, i))));
     }
     cc->OutputSidePackets()
-        .Tag("SIDE_OUTPUT")
+        .Tag(kSideOutputTag)
         .Set(cc->InputSidePackets().Index(0));
     return absl::OkStatus();
   }
@@ -152,7 +157,7 @@ TEST(CalculatorRunner, RunsCalculator) {
         Adopt(new int(input_side_packet_content));
     MP_ASSERT_OK(runner.Run());
     EXPECT_EQ(input_side_packet_content,
-              runner.OutputSidePackets().Tag("SIDE_OUTPUT").Get<int>());
+              runner.OutputSidePackets().Tag(kSideOutputTag).Get<int>());
     const auto& outputs = runner.Outputs();
     ASSERT_EQ(3, outputs.NumEntries());
 
@@ -209,9 +214,9 @@ TEST(CalculatorRunner, MultiTagTestCalculatorOk) {
   const auto& outputs = runner.Outputs();
   ASSERT_EQ(3, outputs.NumEntries());
   for (int ts = 0; ts < 5; ++ts) {
-    const std::vector<Packet>& a_packets = outputs.Tag("A").packets;
+    const std::vector<Packet>& a_packets = outputs.Tag(kATag).packets;
-    const std::vector<Packet>& b_packets = outputs.Tag("B").packets;
+    const std::vector<Packet>& b_packets = outputs.Tag(kBTag).packets;
-    const std::vector<Packet>& c_packets = outputs.Tag("").packets;
+    const std::vector<Packet>& c_packets = outputs.Tag(kTag).packets;
     EXPECT_EQ(Timestamp(ts), a_packets[ts].Timestamp());
     EXPECT_EQ(Timestamp(ts), b_packets[ts].Timestamp());
     EXPECT_EQ(Timestamp(ts), c_packets[ts].Timestamp());

mediapipe/framework/collection_test.cc

@@ -24,6 +24,10 @@
 namespace mediapipe {
 namespace {
 
+constexpr char kTag2Tag[] = "TAG_2";
+constexpr char kTag0Tag[] = "TAG_0";
+constexpr char kTag1Tag[] = "TAG_1";
+
 TEST(CollectionTest, BasicByIndex) {
   tool::TagAndNameInfo info;
   info.names.push_back("name_1");
@@ -55,14 +59,14 @@ TEST(CollectionTest, BasicByTag) {
   info.names.push_back("name_2");
   info.tags.push_back("TAG_2");
   internal::Collection<int> collection(info);
-  collection.Tag("TAG_1") = 101;
+  collection.Tag(kTag1Tag) = 101;
-  collection.Tag("TAG_0") = 100;
+  collection.Tag(kTag0Tag) = 100;
-  collection.Tag("TAG_2") = 102;
+  collection.Tag(kTag2Tag) = 102;
 
   // Test the stored values.
-  EXPECT_EQ(100, collection.Tag("TAG_0"));
+  EXPECT_EQ(100, collection.Tag(kTag0Tag));
-  EXPECT_EQ(101, collection.Tag("TAG_1"));
+  EXPECT_EQ(101, collection.Tag(kTag1Tag));
-  EXPECT_EQ(102, collection.Tag("TAG_2"));
+  EXPECT_EQ(102, collection.Tag(kTag2Tag));
   // Test access using a range based for.
   int i = 0;
   for (int num : collection) {

mediapipe/framework/formats/tensor.cc

@@ -134,6 +134,21 @@ void Tensor::AllocateMtlBuffer(id<MTLDevice> device) const {
 #endif  // MEDIAPIPE_METAL_ENABLED
 
 #if MEDIAPIPE_OPENGL_ES_VERSION >= MEDIAPIPE_OPENGL_ES_30
+bool Tensor::NeedsHalfFloatRenderTarget() const {
+  static bool has_color_buffer_float =
+      gl_context_->HasGlExtension("WEBGL_color_buffer_float") ||
+      gl_context_->HasGlExtension("EXT_color_buffer_float");
+  if (!has_color_buffer_float) {
+    static bool has_color_buffer_half_float =
+        gl_context_->HasGlExtension("EXT_color_buffer_half_float");
+    LOG_IF(FATAL, !has_color_buffer_half_float)
+        << "EXT_color_buffer_half_float or WEBGL_color_buffer_float "
+        << "required on web to use MP tensor";
+    return true;
+  }
+  return false;
+}
+
 Tensor::OpenGlTexture2dView Tensor::GetOpenGlTexture2dReadView() const {
   LOG_IF(FATAL, valid_ == kValidNone)
       << "Tensor must be written prior to read from.";
@@ -164,8 +179,24 @@ Tensor::OpenGlTexture2dView Tensor::GetOpenGlTexture2dReadView() const {
     // Set alignment for the proper value (default) to avoid address sanitizer
     // error "out of boundary reading".
     glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
+#ifdef __EMSCRIPTEN__
+    // Under WebGL1, format must match in order to use glTexSubImage2D, so if we
+    // have a half-float texture, then uploading from GL_FLOAT here would fail.
+    // We change the texture's data type to float here to accommodate.
+    // Furthermore, for a full-image replacement operation, glTexImage2D is
+    // expected to be more performant than glTexSubImage2D. Note that for WebGL2
+    // we cannot use glTexImage2D, because we allocate using glTexStorage2D in
+    // that case, which is incompatible.
+    if (gl_context_->GetGlVersion() == mediapipe::GlVersion::kGLES2) {
+      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texture_width_, texture_height_,
+                   0, GL_RGBA, GL_FLOAT, temp_buffer.get());
+      texture_is_half_float_ = false;
+    } else
+#endif  // __EMSCRIPTEN__
+    {
       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, texture_width_, texture_height_,
                       GL_RGBA, GL_FLOAT, temp_buffer.get());
+    }
     glBindTexture(GL_TEXTURE_2D, 0);
     valid_ |= kValidOpenGlTexture2d;
   }
@@ -175,6 +206,16 @@ Tensor::OpenGlTexture2dView Tensor::GetOpenGlTexture2dReadView() const {
 Tensor::OpenGlTexture2dView Tensor::GetOpenGlTexture2dWriteView() const {
   auto lock = absl::make_unique<absl::MutexLock>(&view_mutex_);
   AllocateOpenGlTexture2d();
+#ifdef __EMSCRIPTEN__
+  // On web, we may have to change type from float to half-float
+  if (!texture_is_half_float_ && NeedsHalfFloatRenderTarget()) {
+    glBindTexture(GL_TEXTURE_2D, opengl_texture2d_);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texture_width_, texture_height_, 0,
+                 GL_RGBA, GL_HALF_FLOAT_OES, 0 /* data */);
+    glBindTexture(GL_TEXTURE_2D, 0);
+    texture_is_half_float_ = true;
+  }
+#endif
   valid_ = kValidOpenGlTexture2d;
   return {opengl_texture2d_, std::move(lock)};
 }
@@ -255,8 +296,18 @@ void Tensor::AllocateOpenGlTexture2d() const {
           << "with GLES 2.0";
       // Allocate the image data; note that it's no longer RGBA32F, so will be
       // lower precision.
+      auto type = GL_FLOAT;
+      // On web, we might need to change type to half-float (e.g. for iOS-
+      // Safari) in order to have a valid framebuffer. See b/194442743 for more
+      // details.
+#ifdef __EMSCRIPTEN__
+      if (NeedsHalfFloatRenderTarget()) {
+        type = GL_HALF_FLOAT_OES;
+        texture_is_half_float_ = true;
+      }
+#endif  // __EMSCRIPTEN
       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texture_width_, texture_height_,
-                   0, GL_RGBA, GL_FLOAT, 0 /* data */);
+                   0, GL_RGBA, type, 0 /* data */);
     }
     glBindTexture(GL_TEXTURE_2D, 0);
     glGenFramebuffers(1, &frame_buffer_);
@@ -443,7 +494,6 @@ Tensor::CpuReadView Tensor::GetCpuReadView() const {
           glPixelStorei(GL_PACK_ALIGNMENT, 4);
           glReadPixels(0, 0, texture_width_, texture_height_, GL_RGBA, GL_FLOAT,
                        buffer);
-
           uint8_t* dest_buffer = reinterpret_cast<uint8_t*>(cpu_buffer_);
           const int actual_depth_size =
               BhwcDepthFromShape(shape_) * element_size();

mediapipe/framework/formats/tensor.h

@@ -266,11 +266,15 @@ class Tensor {
   mutable GLuint frame_buffer_ = GL_INVALID_INDEX;
   mutable int texture_width_;
   mutable int texture_height_;
+#ifdef __EMSCRIPTEN__
+  mutable bool texture_is_half_float_ = false;
+#endif  // __EMSCRIPTEN__
   void AllocateOpenGlTexture2d() const;
 #if MEDIAPIPE_OPENGL_ES_VERSION >= MEDIAPIPE_OPENGL_ES_31
   mutable GLuint opengl_buffer_ = GL_INVALID_INDEX;
   void AllocateOpenGlBuffer() const;
 #endif  // MEDIAPIPE_OPENGL_ES_VERSION >= MEDIAPIPE_OPENGL_ES_31
+  bool NeedsHalfFloatRenderTarget() const;
 #endif  // MEDIAPIPE_OPENGL_ES_VERSION >= MEDIAPIPE_OPENGL_ES_30
 };
 

mediapipe/framework/graph_validation_test.cc

@@ -31,6 +31,11 @@ namespace mediapipe {
 
 namespace {
 
+constexpr char kOutputTag[] = "OUTPUT";
+constexpr char kEnableTag[] = "ENABLE";
+constexpr char kSelectTag[] = "SELECT";
+constexpr char kSideinputTag[] = "SIDEINPUT";
+
 // Shows validation success for a graph and a subgraph.
 TEST(GraphValidationTest, InitializeGraphFromProtos) {
   auto config_1 = ParseTextProtoOrDie<CalculatorGraphConfig>(R"pb(
@@ -323,20 +328,21 @@ TEST(GraphValidationTest, OptionalSubgraphStreamsMismatched) {
 class OptionalSideInputTestCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->InputSidePackets().Tag("SIDEINPUT").Set<std::string>().Optional();
+    cc->InputSidePackets().Tag(kSideinputTag).Set<std::string>().Optional();
-    cc->Inputs().Tag("SELECT").Set<int>().Optional();
+    cc->Inputs().Tag(kSelectTag).Set<int>().Optional();
-    cc->Inputs().Tag("ENABLE").Set<bool>().Optional();
+    cc->Inputs().Tag(kEnableTag).Set<bool>().Optional();
-    cc->Outputs().Tag("OUTPUT").Set<std::string>();
+    cc->Outputs().Tag(kOutputTag).Set<std::string>();
     return absl::OkStatus();
   }
 
   absl::Status Process(CalculatorContext* cc) final {
     std::string value("default");
-    if (cc->InputSidePackets().HasTag("SIDEINPUT")) {
+    if (cc->InputSidePackets().HasTag(kSideinputTag)) {
-      value = cc->InputSidePackets().Tag("SIDEINPUT").Get<std::string>();
+      value = cc->InputSidePackets().Tag(kSideinputTag).Get<std::string>();
     }
-    cc->Outputs().Tag("OUTPUT").Add(new std::string(value),
+    cc->Outputs()
-                                    cc->InputTimestamp());
+        .Tag(kOutputTag)
+        .Add(new std::string(value), cc->InputTimestamp());
     return absl::OkStatus();
   }
 };

mediapipe/framework/packet_registration_test.cc

@@ -26,17 +26,20 @@ namespace {
 
 namespace test_ns {
 
+constexpr char kOutTag[] = "OUT";
+constexpr char kInTag[] = "IN";
+
 class TestSinkCalculator : public CalculatorBase {
  public:
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->Inputs().Tag("IN").Set<mediapipe::InputOnlyProto>();
+    cc->Inputs().Tag(kInTag).Set<mediapipe::InputOnlyProto>();
-    cc->Outputs().Tag("OUT").Set<int>();
+    cc->Outputs().Tag(kOutTag).Set<int>();
     return absl::OkStatus();
   }
 
   absl::Status Process(CalculatorContext* cc) override {
-    int x = cc->Inputs().Tag("IN").Get<mediapipe::InputOnlyProto>().x();
+    int x = cc->Inputs().Tag(kInTag).Get<mediapipe::InputOnlyProto>().x();
-    cc->Outputs().Tag("OUT").AddPacket(
+    cc->Outputs().Tag(kOutTag).AddPacket(
         MakePacket<int>(x).At(cc->InputTimestamp()));
     return absl::OkStatus();
   }

mediapipe/framework/test_calculators.cc

@@ -34,6 +34,19 @@
 
 namespace mediapipe {
 
+constexpr char kOutTag[] = "OUT";
+constexpr char kClockTag[] = "CLOCK";
+constexpr char kSleepMicrosTag[] = "SLEEP_MICROS";
+constexpr char kCloseTag[] = "CLOSE";
+constexpr char kProcessTag[] = "PROCESS";
+constexpr char kOpenTag[] = "OPEN";
+constexpr char kTag[] = "";
+constexpr char kMeanTag[] = "MEAN";
+constexpr char kDataTag[] = "DATA";
+constexpr char kPairTag[] = "PAIR";
+constexpr char kLowTag[] = "LOW";
+constexpr char kHighTag[] = "HIGH";
+
 using RandomEngine = std::mt19937_64;
 
 // A Calculator that outputs twice the value of its input packet (an int).
@@ -95,9 +108,9 @@ class TaggedIntSplitterPacketGenerator : public PacketGenerator {
       PacketTypeSet* input_side_packets,                 //
       PacketTypeSet* output_side_packets) {
     input_side_packets->Index(0).Set<uint64>();
-    output_side_packets->Tag("HIGH").Set<uint32>();
+    output_side_packets->Tag(kHighTag).Set<uint32>();
-    output_side_packets->Tag("LOW").Set<uint32>();
+    output_side_packets->Tag(kLowTag).Set<uint32>();
-    output_side_packets->Tag("PAIR").Set<std::pair<uint32, uint32>>();
+    output_side_packets->Tag(kPairTag).Set<std::pair<uint32, uint32>>();
     return absl::OkStatus();
   }
 
@@ -108,9 +121,9 @@ class TaggedIntSplitterPacketGenerator : public PacketGenerator {
     uint64 value = input_side_packets.Index(0).Get<uint64>();
     uint32 high = value >> 32;
     uint32 low = value & 0xFFFFFFFF;
-    output_side_packets->Tag("HIGH") = Adopt(new uint32(high));
+    output_side_packets->Tag(kHighTag) = Adopt(new uint32(high));
-    output_side_packets->Tag("LOW") = Adopt(new uint32(low));
+    output_side_packets->Tag(kLowTag) = Adopt(new uint32(low));
-    output_side_packets->Tag("PAIR") =
+    output_side_packets->Tag(kPairTag) =
         Adopt(new std::pair<uint32, uint32>(high, low));
     return absl::OkStatus();
   }
@@ -221,8 +234,8 @@ class StdDevCalculator : public CalculatorBase {
   StdDevCalculator() {}
 
   static absl::Status GetContract(CalculatorContract* cc) {
-    cc->Inputs().Tag("DATA").Set<int>();
+    cc->Inputs().Tag(kDataTag).Set<int>();
-    cc->Inputs().Tag("MEAN").Set<double>();
+    cc->Inputs().Tag(kMeanTag).Set<double>();
     cc->Outputs().Index(0).Set<int>();
     return absl::OkStatus();
   }
@@ -234,15 +247,15 @@ class StdDevCalculator : public CalculatorBase {
 
   absl::Status Process(CalculatorContext* cc) final {
     if (cc->InputTimestamp() == Timestamp::PreStream()) {
-      RET_CHECK(cc->Inputs().Tag("DATA").Value().IsEmpty());
+      RET_CHECK(cc->Inputs().Tag(kDataTag).Value().IsEmpty());
-      RET_CHECK(!cc->Inputs().Tag("MEAN").Value().IsEmpty());
+      RET_CHECK(!cc->Inputs().Tag(kMeanTag).Value().IsEmpty());
-      mean_ = cc->Inputs().Tag("MEAN").Get<double>();
+      mean_ = cc->Inputs().Tag(kMeanTag).Get<double>();
       initialized_ = true;
     } else {
       RET_CHECK(initialized_);
-      RET_CHECK(!cc->Inputs().Tag("DATA").Value().IsEmpty());
+      RET_CHECK(!cc->Inputs().Tag(kDataTag).Value().IsEmpty());
-      RET_CHECK(cc->Inputs().Tag("MEAN").Value().IsEmpty());
+      RET_CHECK(cc->Inputs().Tag(kMeanTag).Value().IsEmpty());
-      double diff = cc->Inputs().Tag("DATA").Get<int>() - mean_;
+      double diff = cc->Inputs().Tag(kDataTag).Get<int>() - mean_;
       cummulative_variance_ += diff * diff;
       ++count_;
     }
@@ -564,8 +577,8 @@ class LambdaCalculator : public CalculatorBase {
          id < cc->Outputs().EndId(); ++id) {
       cc->Outputs().Get(id).SetAny();
     }
-    if (cc->InputSidePackets().HasTag("") > 0) {
+    if (cc->InputSidePackets().HasTag(kTag) > 0) {
-      cc->InputSidePackets().Tag("").Set<ProcessFunction>();
+      cc->InputSidePackets().Tag(kTag).Set<ProcessFunction>();
     }
     for (const std::string& tag : {"OPEN", "PROCESS", "CLOSE"}) {
       if (cc->InputSidePackets().HasTag(tag)) {
@@ -576,24 +589,24 @@ class LambdaCalculator : public CalculatorBase {
   }
 
   absl::Status Open(CalculatorContext* cc) final {
-    if (cc->InputSidePackets().HasTag("OPEN")) {
+    if (cc->InputSidePackets().HasTag(kOpenTag)) {
       return GetContextFn(cc, "OPEN")(cc);
     }
     return absl::OkStatus();
   }
 
   absl::Status Process(CalculatorContext* cc) final {
-    if (cc->InputSidePackets().HasTag("PROCESS")) {
+    if (cc->InputSidePackets().HasTag(kProcessTag)) {
       return GetContextFn(cc, "PROCESS")(cc);
     }
-    if (cc->InputSidePackets().HasTag("") > 0) {
+    if (cc->InputSidePackets().HasTag(kTag) > 0) {
       return GetProcessFn(cc, "")(cc->Inputs(), &cc->Outputs());
     }
     return absl::OkStatus();
   }
 
   absl::Status Close(CalculatorContext* cc) final {
-    if (cc->InputSidePackets().HasTag("CLOSE")) {
+    if (cc->InputSidePackets().HasTag(kCloseTag)) {
       return GetContextFn(cc, "CLOSE")(cc);
     }
     return absl::OkStatus();
@@ -645,17 +658,18 @@ class PassThroughWithSleepCalculator : public CalculatorBase {
   static absl::Status GetContract(CalculatorContract* cc) {
     cc->Inputs().Index(0).Set<int>();
     cc->Outputs().Index(0).SetSameAs(&cc->Inputs().Index(0));
-    cc->InputSidePackets().Tag("SLEEP_MICROS").Set<int>();
+    cc->InputSidePackets().Tag(kSleepMicrosTag).Set<int>();
-    cc->InputSidePackets().Tag("CLOCK").Set<std::shared_ptr<Clock>>();
+    cc->InputSidePackets().Tag(kClockTag).Set<std::shared_ptr<Clock>>();
     return absl::OkStatus();
   }
   absl::Status Open(CalculatorContext* cc) final {
     cc->SetOffset(TimestampDiff(0));
-    sleep_micros_ = cc->InputSidePackets().Tag("SLEEP_MICROS").Get<int>();
+    sleep_micros_ = cc->InputSidePackets().Tag(kSleepMicrosTag).Get<int>();
     if (sleep_micros_ < 0) {
       return absl::InternalError("SLEEP_MICROS should be >= 0");
     }
-    clock_ = cc->InputSidePackets().Tag("CLOCK").Get<std::shared_ptr<Clock>>();
+    clock_ =
+        cc->InputSidePackets().Tag(kClockTag).Get<std::shared_ptr<Clock>>();
     return absl::OkStatus();
   }
   absl::Status Process(CalculatorContext* cc) final {
@@ -678,8 +692,8 @@ class MultiplyIntCalculator : public CalculatorBase {
     cc->Inputs().Index(0).Set<int>();
     cc->Inputs().Index(1).SetSameAs(&cc->Inputs().Index(0));
     // cc->Outputs().Index(0).SetSameAs(&cc->Inputs().Index(0));
-    RET_CHECK(cc->Outputs().HasTag("OUT"));
+    RET_CHECK(cc->Outputs().HasTag(kOutTag));
-    cc->Outputs().Tag("OUT").SetSameAs(&cc->Inputs().Index(0));
+    cc->Outputs().Tag(kOutTag).SetSameAs(&cc->Inputs().Index(0));
     return absl::OkStatus();
   }
   absl::Status Open(CalculatorContext* cc) final {
@@ -689,7 +703,7 @@ class MultiplyIntCalculator : public CalculatorBase {
   absl::Status Process(CalculatorContext* cc) final {
     int x = cc->Inputs().Index(0).Value().Get<int>();
     int y = cc->Inputs().Index(1).Value().Get<int>();
-    cc->Outputs().Tag("OUT").Add(new int(x * y), cc->InputTimestamp());
+    cc->Outputs().Tag(kOutTag).Add(new int(x * y), cc->InputTimestamp());
     return absl::OkStatus();
   }
 };

mediapipe/java/com/google/mediapipe/mediapipe_aar.bzl

@@ -60,6 +60,18 @@ def mediapipe_aar(
       assets: additional assets to be included into the archive.
       assets_dir: path where the assets will the packaged.
     """
+
+    # When "--define EXCLUDE_OPENCV_SO_LIB=1" is set in the build command,
+    # the OpenCV so libraries will be excluded from the AAR package to
+    # save the package size.
+    native.config_setting(
+        name = "exclude_opencv_so_lib",
+        define_values = {
+            "EXCLUDE_OPENCV_SO_LIB": "1",
+        },
+        visibility = ["//visibility:public"],
+    )
+
     _mediapipe_jni(
         name = name + "_jni",
         gen_libmediapipe = gen_libmediapipe,
@@ -133,6 +145,7 @@ EOF
         ] + select({
             "//conditions:default": [":" + name + "_jni_opencv_cc_lib"],
             "//mediapipe/framework/port:disable_opencv": [],
+            "exclude_opencv_so_lib": [],
         }),
         assets = assets,
         assets_dir = assets_dir,

mediapipe/modules/objectron/calculators/box.cc

@@ -245,14 +245,6 @@ void Box::Fit(const std::vector<T>& vertices) {
   auto system_g = system_h.colPivHouseholderQr();
   auto solution = system_g.solve(v).eval();
   transformation_.topLeftCorner<3, 4>() = solution.transpose();
-
-  // Adjust rotation matrix to its nearest orthogonal matrix.
-  const auto rotation = transformation_.topLeftCorner<3, 3>();
-  Eigen::JacobiSVD<Eigen::Matrix3f> svd(
-      rotation, Eigen::ComputeFullV | Eigen::ComputeFullU);
-  const Eigen::Matrix3f matrix_u = svd.matrixU();
-  const Eigen::Matrix3f matrix_v = svd.matrixV();
-  transformation_.topLeftCorner<3, 3>() = matrix_u * matrix_v.transpose();
   Update();
 }
 

mediapipe/python/solution_base.py

@@ -254,11 +254,11 @@ class SolutionBase:
     for stream_name in self._output_stream_type_info.keys():
       self._graph.observe_output_stream(stream_name, callback, True)
 
-    input_side_packets = {
+    self._input_side_packets = {
         name: self._make_packet(self._side_input_type_info[name], data)
         for name, data in (side_inputs or {}).items()
     }
-    self._graph.start_run(input_side_packets)
+    self._graph.start_run(self._input_side_packets)
 
   # TODO: Use "inspect.Parameter" to fetch the input argument names and
   # types from "_input_stream_type_info" and then auto generate the process
@@ -353,6 +353,12 @@ class SolutionBase:
     self._input_stream_type_info = None
     self._output_stream_type_info = None
 
+  def reset(self) -> None:
+    """Resets the graph for another run."""
+    if self._graph:
+      self._graph.close()
+      self._graph.start_run(self._input_side_packets)
+
   def _initialize_graph_interface(
       self,
       validated_graph: validated_graph_config.ValidatedGraphConfig,

mediapipe/python/solution_base_test.py

@@ -298,6 +298,56 @@ class SolutionBaseTest(parameterized.TestCase):
             'ImageTransformation.output_height': 0
         })
 
+  @parameterized.named_parameters(('graph_without_side_packets', """
+      input_stream: 'image_in'
+      output_stream: 'image_out'
+      node {
+        calculator: 'ImageTransformationCalculator'
+        input_stream: 'IMAGE:image_in'
+        output_stream: 'IMAGE:transformed_image_in'
+      }
+      node {
+        calculator: 'ImageTransformationCalculator'
+        input_stream: 'IMAGE:transformed_image_in'
+        output_stream: 'IMAGE:image_out'
+      }
+      """, None), ('graph_with_side_packets', """
+      input_stream: 'image_in'
+      input_side_packet: 'allow_signal'
+      input_side_packet: 'rotation_degrees'
+      output_stream: 'image_out'
+      node {
+        calculator: 'ImageTransformationCalculator'
+        input_stream: 'IMAGE:image_in'
+        input_side_packet: 'ROTATION_DEGREES:rotation_degrees'
+        output_stream: 'IMAGE:transformed_image_in'
+      }
+      node {
+        calculator: 'GateCalculator'
+        input_stream: 'transformed_image_in'
+        input_side_packet: 'ALLOW:allow_signal'
+        output_stream: 'image_out_to_transform'
+      }
+      node {
+        calculator: 'ImageTransformationCalculator'
+        input_stream: 'IMAGE:image_out_to_transform'
+        input_side_packet: 'ROTATION_DEGREES:rotation_degrees'
+        output_stream: 'IMAGE:image_out'
+      }""", {
+          'allow_signal': True,
+          'rotation_degrees': 0
+      }))
+  def test_solution_reset(self, text_config, side_inputs):
+    config_proto = text_format.Parse(text_config,
+                                     calculator_pb2.CalculatorGraphConfig())
+    input_image = np.arange(27, dtype=np.uint8).reshape(3, 3, 3)
+    with solution_base.SolutionBase(
+        graph_config=config_proto, side_inputs=side_inputs) as solution:
+      for _ in range(20):
+        outputs = solution.process(input_image)
+        self.assertTrue(np.array_equal(input_image, outputs.image_out))
+        solution.reset()
+
   def _process_and_verify(self,
                           config_proto,
                           side_inputs=None,

mediapipe/python/solutions/objectron_test.py

@@ -26,7 +26,7 @@ import numpy.testing as npt
 from mediapipe.python.solutions import objectron as mp_objectron
 
 TEST_IMAGE_PATH = 'mediapipe/python/solutions/testdata'
-DIFF_THRESHOLD = 35  # pixels
+DIFF_THRESHOLD = 30  # pixels
 EXPECTED_BOX_COORDINATES_PREDICTION = [[[236, 413], [408, 474], [135, 457],
                                         [383, 505], [80, 478], [408, 345],
                                         [130, 347], [384, 355], [72, 353]],