--- a/dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp
+++ b/dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp
@@ -103,16 +103,17 @@ FFmpegVideoDecoder<LIBAV_VER>::PtsCorrec
 FFmpegVideoDecoder<LIBAV_VER>::FFmpegVideoDecoder(FFmpegLibWrapper* aLib,
   FlushableTaskQueue* aTaskQueue, MediaDataDecoderCallback* aCallback,
   const VideoInfo& aConfig,
   ImageContainer* aImageContainer)
   : FFmpegDataDecoder(aLib, aTaskQueue, aCallback, GetCodecId(aConfig.mMimeType))
   , 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.
   mExtraData = new MediaByteBuffer;
   mExtraData->AppendElements(*aConfig.mExtraData);
 }
 
 RefPtr<MediaDataDecoder::InitPromise>
@@ -205,17 +206,17 @@ FFmpegVideoDecoder<LIBAV_VER>::DecodeRes
 FFmpegVideoDecoder<LIBAV_VER>::DoDecode(MediaRawData* aSample,
                                         uint8_t* aData, int aSize)
 {
   AVPacket packet;
   mLib->av_init_packet(&packet);
 
   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;
 
   // LibAV provides no API to retrieve the decoded sample's duration.
   // (FFmpeg >= 1.0 provides av_frame_get_pkt_duration)
   // As such we instead use a map using the dts as key that we will retrieve
   // later.
@@ -307,17 +308,17 @@ FFmpegVideoDecoder<LIBAV_VER>::DoDecode(
   }
   return DecodeResult::DECODE_NO_FRAME;
 }
 
 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();
 }
 
 void
 FFmpegVideoDecoder<LIBAV_VER>::ProcessFlush()
 {

--- a/dom/media/platforms/ffmpeg/FFmpegVideoDecoder.h
+++ b/dom/media/platforms/ffmpeg/FFmpegVideoDecoder.h
@@ -77,16 +77,17 @@ private:
   private:
     int64_t mNumFaultyPts; /// Number of incorrect PTS values so far
     int64_t mNumFaultyDts; /// Number of incorrect DTS values so far
     int64_t mLastPts;       /// PTS of the last frame
     int64_t mLastDts;       /// DTS of the last frame
   };
 
   PtsCorrectionContext mPtsContext;
+  int64_t mLastInputDts;
 
   class DurationMap {
   public:
     typedef Pair<int64_t, int64_t> DurationElement;
 
     // Insert Key and Duration pair at the end of our map.
     void Insert(int64_t aKey, int64_t aDuration)
     {