From e15d5a797b08a9187bee0b803b9f04694a6d40ea Mon Sep 17 00:00:00 2001
From: MediaPipe Team <mediapipe-team@google.com>
Date: Thu, 29 Jun 2023 13:42:27 -0700
Subject: [PATCH] Do not send PreviousLoopback output packets to closed streams

PiperOrigin-RevId: 544449979
---
 mediapipe/calculators/core/previous_loopback_calculator.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mediapipe/calculators/core/previous_loopback_calculator.cc b/mediapipe/calculators/core/previous_loopback_calculator.cc
index d67e6c061..36ee0f2d7 100644
--- a/mediapipe/calculators/core/previous_loopback_calculator.cc
+++ b/mediapipe/calculators/core/previous_loopback_calculator.cc
@@ -123,7 +123,10 @@ class PreviousLoopbackCalculator : public Node {
           // However, LOOP packet is empty.
           kPrevLoop(cc).SetNextTimestampBound(main_spec.timestamp + 1);
         } else {
-          kPrevLoop(cc).Send(loop_candidate.At(main_spec.timestamp));
+          // Avoids sending leftovers to a stream that's already closed.
+          if (!kPrevLoop(cc).IsClosed()) {
+            kPrevLoop(cc).Send(loop_candidate.At(main_spec.timestamp));
+          }
         }
         loop_packets_.pop_front();
         main_packet_specs_.pop_front();