Bug 1270323: [ffmpeg] P3. Use the dts of the last sample input, not the dts of the last decoded sample. r=cpearce

Amendment to bug 1244410. If no frames had been output yet, last dts would have been INT64_MIN.

MozReview-Commit-ID: LOdWLpyuLYm

--HG--
extra : rebase_source : f842d2214b1e82f3b069e843157b95d87e62fa01

dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp

@@ -108,6 +108,7 @@ FFmpegVideoDecoder<LIBAV_VER>::FFmpegVideoDecoder(FFmpegLibWrapper* aLib,
   , mImageContainer(aImageContainer)
   , mInfo(aConfig)
   , mCodecParser(nullptr)
+  , mLastInputDts(INT64_MIN)
 {
   MOZ_COUNT_CTOR(FFmpegVideoDecoder);
   // Use a new MediaByteBuffer as the object will be modified during initialization.
@@ -210,7 +211,7 @@ FFmpegVideoDecoder<LIBAV_VER>::DoDecode(MediaRawData* aSample,
 
   packet.data = aData;
   packet.size = aSize;
-  packet.dts = aSample->mTimecode;
+  packet.dts = mLastInputDts = aSample->mTimecode;
   packet.pts = aSample->mTime;
   packet.flags = aSample->mKeyframe ? AV_PKT_FLAG_KEY : 0;
   packet.pos = aSample->mOffset;
@@ -312,7 +313,7 @@ void
 FFmpegVideoDecoder<LIBAV_VER>::ProcessDrain()
 {
   RefPtr<MediaRawData> empty(new MediaRawData());
-  empty->mTimecode = mPtsContext.LastDts();
+  empty->mTimecode = mLastInputDts;
   while (DoDecode(empty) == DecodeResult::DECODE_FRAME) {
   }
   mCallback->DrainComplete();

dom/media/platforms/ffmpeg/FFmpegVideoDecoder.h

@@ -82,6 +82,7 @@ private:
   };
 
   PtsCorrectionContext mPtsContext;
+  int64_t mLastInputDts;
 
   class DurationMap {
   public: