tor-browser

commit fa7d0e1257b3fb6b84a02978be0c25664b122766
parent 20ccceccb14fb410de75a67867434695600d314d
Author: Andreas Pehrson <apehrson@mozilla.com>
Date:   Fri,  5 Dec 2025 16:34:21 +0000

Bug 1992567 - Enforce a hard limit of 1 frame in flight in WebRTC GMP encoder. r=webrtc-reviewers,bwc

This avoids an ~unbounded memory leak when OpenH264 is not able to keep up with
encoding in real-time.

Also report frame drops from Encode() upwards.

Differential Revision: https://phabricator.services.mozilla.com/D272451

Diffstat:
M
dom/media/webrtc/libwebrtcglue/WebrtcGmpVideoCodec.cpp
 | 
32
++++++++++++++++++++++++++------

1 file changed, 26 insertions(+), 6 deletions(-)
diff --git a/dom/media/webrtc/libwebrtcglue/WebrtcGmpVideoCodec.cpp b/dom/media/webrtc/libwebrtcglue/WebrtcGmpVideoCodec.cpp
@@ -340,6 +340,14 @@ void WebrtcGmpVideoEncoder::RegetEncoderForResolutionChange(uint32_t aWidth,
 void WebrtcGmpVideoEncoder::Encode_g(
     const webrtc::VideoFrame& aInputImage,
     std::vector<webrtc::VideoFrameType> aFrameTypes) {
+  auto reportDroppedOnExit = MakeScopeExit([&] {
+    MutexAutoLock lock(mCallbackMutex);
+    if (mCallback) {
+      mCallback->OnDroppedFrame(
+          webrtc::EncodedImageCallback::DropReason::kDroppedByEncoder);
+    }
+  });
+
   if (!mGMP) {
     // destroyed via Terminate(), failed to init, or just not initted yet
     GMP_LOG_DEBUG("GMP Encode: not initted yet");
@@ -347,6 +355,13 @@ void WebrtcGmpVideoEncoder::Encode_g(
   }
   MOZ_ASSERT(mHost);
 
+  if (mInputImageMap.Length() >= kMaxImagesInFlight) {
+    GMP_LOG_WARNING(
+        "GMP Encode: Max number of frames already in flight. Dropping this "
+        "one.");
+    return;
+  }
+
   if (static_cast<uint32_t>(aInputImage.width()) != mCodecParams.mWidth ||
       static_cast<uint32_t>(aInputImage.height()) != mCodecParams.mHeight) {
     GMP_LOG_DEBUG("GMP Encode: resolution change from %ux%u to %dx%d",
@@ -423,18 +438,23 @@ void WebrtcGmpVideoEncoder::Encode_g(
   MOZ_RELEASE_ASSERT(mInputImageMap.IsEmpty() ||
                      mInputImageMap.LastElement().ntp_timestamp_ms <
                          aInputImage.ntp_time_ms());
-  mInputImageMap.AppendElement(
-      InputImageData{.gmp_timestamp_us = gmpTimestamp,
-                     .ntp_timestamp_ms = aInputImage.ntp_time_ms(),
-                     .timestamp_us = aInputImage.timestamp_us(),
-                     .rtp_timestamp = aInputImage.rtp_timestamp(),
-                     .frame_config = frameConfigs[0]});
 
   GMP_LOG_DEBUG("GMP Encode: %" PRIu64, (frame->Timestamp()));
   err = mGMP->Encode(std::move(frame), codecSpecificInfo, gmp_frame_types);
   if (err != GMPNoErr) {
     GMP_LOG_DEBUG("GMP Encode: failed to encode frame");
+    return;
   }
+
+  // Once in mInputImageMap, frame drops are reported by GMP callbacks
+  // (Encoded/Dropped).
+  reportDroppedOnExit.release();
+  mInputImageMap.AppendElement(
+      InputImageData{.gmp_timestamp_us = gmpTimestamp,
+                     .ntp_timestamp_ms = aInputImage.ntp_time_ms(),
+                     .timestamp_us = aInputImage.timestamp_us(),
+                     .rtp_timestamp = aInputImage.rtp_timestamp(),
+                     .frame_config = frameConfigs[0]});
 }
 
 int32_t WebrtcGmpVideoEncoder::RegisterEncodeCompleteCallback(