Bug 1043695 - Add a frame reorder queue. r=cpearce

This fixes the frame drops on test.mp4. For now it just
assumes a reorder depth of 3, but we need to plumb the
actual value through the demuxer.

Based on now-removed code from Edwin's FFmpegH264Decoder.

content/media/fmp4/apple/AppleVTDecoder.cpp

@@ -110,6 +110,7 @@ AppleVTDecoder::Input(mp4_demuxer::MP4Sample* aSample)
 nsresult
 AppleVTDecoder::Flush()
 {
+  mReorderQueue.Clear();
   return Drain();
 }
 
@@ -121,7 +122,7 @@ AppleVTDecoder::Drain()
     LOG("Error %d draining frames", rv);
     return NS_ERROR_FAILURE;
   }
-  return NS_OK;
+  return DrainReorderedFrames();
 }
 
 //
@@ -189,6 +190,15 @@ PlatformCallback(void* decompressionOutputRefCon,
   decoder->OutputFrame(image, frameRef);
 }
 
+nsresult
+AppleVTDecoder::DrainReorderedFrames()
+{
+  while (!mReorderQueue.IsEmpty()) {
+    mCallback->Output(mReorderQueue.Pop());
+  }
+  return NS_OK;
+}
+
 // Copy and return a decoded frame.
 nsresult
 AppleVTDecoder::OutputFrame(CVPixelBufferRef aImage,
@@ -270,7 +280,14 @@ AppleVTDecoder::OutputFrame(CVPixelBufferRef aImage,
   // Unlock the returned image data.
   CVPixelBufferUnlockBaseAddress(aImage, kCVPixelBufferLock_ReadOnly);
 
-  mCallback->Output(data.forget());
+  // Frames come out in DTS order but we need to output them
+  // in composition order.
+  mReorderQueue.Push(data.forget());
+  if (mReorderQueue.Length() > 2) {
+    VideoData* readyData = mReorderQueue.Pop();
+    mCallback->Output(readyData);
+  }
+
   return NS_OK;
 }
 

content/media/fmp4/apple/AppleVTDecoder.h

@@ -11,6 +11,8 @@
 #include "mozilla/RefPtr.h"
 #include "mozilla/ReentrantMonitor.h"
 #include "nsIThread.h"
+#include "ReorderQueue.h"
+
 #include "VideoToolbox/VideoToolbox.h"
 
 namespace mozilla {
@@ -44,11 +46,13 @@ private:
   layers::ImageContainer* mImageContainer;
   CMVideoFormatDescriptionRef mFormat;
   VTDecompressionSessionRef mSession;
+  ReorderQueue mReorderQueue;
 
   // Method to pass a frame to VideoToolbox for decoding.
   nsresult SubmitFrame(mp4_demuxer::MP4Sample* aSample);
   // Method to set up the decompression session.
   nsresult InitializeSession();
+  nsresult DrainReorderedFrames();
 };
 
 } // namespace mozilla

content/media/fmp4/apple/ReorderQueue.h

@@ -0,0 +1,29 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Queue for ordering decoded video frames by presentation time.
+// Decoders often return frames out of order, which we need to
+// buffer so we can forward them in correct presentation order.
+
+#ifndef mozilla_ReorderQueue_h
+#define mozilla_ReorderQueue_h
+
+#include <MediaData.h>
+#include <nsTPriorityQueue.h>
+
+namespace mozilla {
+
+struct ReorderQueueComparator
+{
+  bool LessThan(VideoData* const& a, VideoData* const& b) const
+  {
+    return a->mTime < b->mTime;
+  }
+};
+
+typedef nsTPriorityQueue<VideoData*, ReorderQueueComparator> ReorderQueue;
+
+} // namespace mozilla
+
+#endif // mozilla_ReorderQueue_h