media: Add support for playback of VP8 Alpha video streams

media/filters/ffmpeg_demuxer.cc

Index: media/filters/ffmpeg_demuxer.cc
diff --git a/media/filters/ffmpeg_demuxer.cc b/media/filters/ffmpeg_demuxer.cc
index 56929bcf05172823e0aab9b2ba7d8fe64e4c81b2..9cba36a7a6cc5d113fa5272d2f8f588e693db6b5 100644
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -70,6 +70,10 @@ FFmpegDemuxerStream::FFmpegDemuxerStream(
 }
 
 void FFmpegDemuxerStream::EnqueuePacket(ScopedAVPacket packet) {
+  uint8_t* side_data;

[Tom Finegan, 2013/02/25 22:56:06]

uint8

[vignesh, 2013/02/25 23:33:14]

Done.

+  int side_data_size = 0;
+  AVPacket* pkt;
+
   DCHECK(message_loop_->BelongsToCurrentThread());
 
   if (stopped_ || end_of_stream_) {
@@ -83,11 +87,25 @@ void FFmpegDemuxerStream::EnqueuePacket(ScopedAVPacket packet) {
     LOG(ERROR) << "Format conversion failed.";
   }
 
+  // Get side data if any. For now, the only type of side_data is VP8 Alpha. We
+  // keep this generic so that other side_data types in the future can be
+  // handled the same way as well.
+  pkt = packet.get();
+  av_packet_split_side_data(pkt);
+  side_data = av_packet_get_side_data(pkt,
+                                      AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL,
+                                      &side_data_size);
+
   // If a packet is returned by FFmpeg's av_parser_parse2() the packet will
   // reference inner memory of FFmpeg.  As such we should transfer the packet
   // into memory we control.
   scoped_refptr<DecoderBuffer> buffer;
-  buffer = DecoderBuffer::CopyFrom(packet->data, packet->size);
+  if (side_data_size) {

[Tom Finegan, 2013/02/25 22:56:06]

side_data_size > 0 ?

[vignesh, 2013/02/25 23:33:14]

Done.

+    buffer = DecoderBuffer::CopyFrom(pkt->data, pkt->size, side_data,
+                                     side_data_size);

[Tom Finegan, 2013/02/25 22:56:06]

It would be nice if side_data and side_data_size were on the same line.

[vignesh, 2013/02/25 23:33:14]

Done.

+  } else {
+    buffer = DecoderBuffer::CopyFrom(pkt->data, pkt->size);
+  }
   buffer->SetTimestamp(ConvertStreamTimestamp(
       stream_->time_base, packet->pts));
   buffer->SetDuration(ConvertStreamTimestamp(