Fix incorrect timestamp send to graph and make object tracking work in iOS.

mediapipe/examples/ios/objecttrackinggpu/BUILD

@@ -0,0 +1,70 @@
+# 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.
+
+load(
+    "@build_bazel_rules_apple//apple:ios.bzl",
+    "ios_application",
+)
+load(
+    "//mediapipe/examples/ios:bundle_id.bzl",
+    "BUNDLE_ID_PREFIX",
+    "example_provisioning",
+)
+
+licenses(["notice"])
+
+MIN_IOS_VERSION = "10.0"
+
+alias(
+    name = "objectrackinggpu",
+    actual = "ObjectTrackingGpuApp",
+)
+
+ios_application(
+    name = "ObjectTrackingGpuApp",
+    app_icons = ["//mediapipe/examples/ios/common:AppIcon"],
+    bundle_id = BUNDLE_ID_PREFIX + ".ObjectTrackingGpu",
+    families = [
+        "iphone",
+        "ipad",
+    ],
+    infoplists = [
+        "//mediapipe/examples/ios/common:Info.plist",
+        "Info.plist",
+    ],
+    minimum_os_version = MIN_IOS_VERSION,
+    provisioning_profile = example_provisioning(),
+    deps = [
+        ":ObjectTrackingGpuAppLibrary",
+        "@ios_opencv//:OpencvFramework",
+    ],
+)
+
+objc_library(
+    name = "ObjectTrackingGpuAppLibrary",
+    data = [
+        "//mediapipe/graphs/tracking:mobile_gpu.binarypb",
+        "//mediapipe/models:ssdlite_object_detection.tflite",
+        "//mediapipe/models:ssdlite_object_detection_labelmap.txt",
+    ],
+    deps = [
+        "//mediapipe/examples/ios/common:CommonMediaPipeAppLibrary",
+    ] + select({
+        "//mediapipe:ios_i386": [],
+        "//mediapipe:ios_x86_64": [],
+        "//conditions:default": [
+            "//mediapipe/graphs/tracking:mobile_calculators",
+        ],
+    }),
+)

mediapipe/examples/ios/objecttrackinggpu/Info.plist

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+  <key>CameraPosition</key>
+  <string>front</string>
+  <key>GraphOutputStream</key>
+  <string>output_video</string>
+  <key>GraphInputStream</key>
+  <string>input_video</string>
+  <key>GraphName</key>
+  <string>mobile_gpu</string>
+</dict>
+</plist>

mediapipe/objc/MPPGraph.mm

@@ -46,7 +46,6 @@
   /// Number of frames currently being processed by the graph.
   std::atomic<int32_t> _framesInFlight;
   /// Used as a sequential timestamp for MediaPipe.
-  mediapipe::Timestamp _frameTimestamp;
   int64 _frameNumber;
 
   // Graph config modified to expose requested output streams.
@@ -369,21 +368,16 @@ void CallFrameDelegate(void* wrapperVoid, const std::string& streamName,
                      timestamp:timestamp
                 allowOverwrite:NO];
 }
-
 - (BOOL)sendPixelBuffer:(CVPixelBufferRef)imageBuffer
              intoStream:(const std::string&)inputName
              packetType:(MPPPacketType)packetType {
-  _GTMDevAssert(_frameTimestamp < mediapipe::Timestamp::Done(),
-                @"Trying to send frame after stream is done.");
-  if (_frameTimestamp < mediapipe::Timestamp::Min()) {
-    _frameTimestamp = mediapipe::Timestamp::Min();
-  } else {
-    _frameTimestamp++;
-  }
+  uint64_t us = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::high_resolution_clock::
+                                                                      now().time_since_epoch()).count();
   return [self sendPixelBuffer:imageBuffer
                     intoStream:inputName
                     packetType:packetType
-                     timestamp:_frameTimestamp];
+                     timestamp:mediapipe::Timestamp(us)];
+
 }
 
 - (void)debugPrintGlInfo {