media: Add support for playback of VP8 Alpha video streams

media/filters/ffmpeg_demuxer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/filters/ffmpeg_demuxer.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/stl_util.h"
 #include "base/string_util.h"
 #include "base/task_runner_util.h"
 #include "base/time.h"
 #include "media/base/audio_decoder_config.h"
 #include "media/base/bind_to_loop.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/limits.h"
 #include "media/base/media_switches.h"
 #include "media/base/video_decoder_config.h"
 #include "media/ffmpeg/ffmpeg_common.h"
 #include "media/filters/ffmpeg_glue.h"
 #include "media/filters/ffmpeg_h264_to_annex_b_bitstream_converter.h"
 
+extern "C" {
+#include "third_party/ffmpeg/libavcodec/avcodec.h"

[scherkus (not reviewing), 2013/02/22 23:18:01]

this include should go inside ffmpeg_common.h

[vignesh, 2013/02/25 21:51:42]

Done.

+}
+
 namespace media {
 
 //
 // FFmpegDemuxerStream
 //
 FFmpegDemuxerStream::FFmpegDemuxerStream(
     FFmpegDemuxer* demuxer,
     AVStream* stream)
     : demuxer_(demuxer),
       message_loop_(base::MessageLoopProxy::current()),
@@ skipping 23 matching lines @@
   // Calculate the duration.
   duration_ = ConvertStreamTimestamp(stream->time_base, stream->duration);
 
   if (stream_->codec->codec_id == CODEC_ID_H264) {
     bitstream_converter_.reset(
         new FFmpegH264ToAnnexBBitstreamConverter(stream_->codec));
   }
 }
 
 void FFmpegDemuxerStream::EnqueuePacket(ScopedAVPacket packet) {
+

[scherkus (not reviewing), 2013/02/22 23:18:01]

remove extra blank line

[vignesh, 2013/02/25 21:51:42]

Done.

+  uint8_t* side_data;
+  int side_data_size = 0;
+  AVPacket* pkt;
+
   DCHECK(message_loop_->BelongsToCurrentThread());
 
   if (stopped_ || end_of_stream_) {
     NOTREACHED() << "Attempted to enqueue packet on a stopped stream";
     return;
   }
 
   // Convert the packet if there is a bitstream filter.
   if (packet->data && bitstream_converter_enabled_ &&
       !bitstream_converter_->ConvertPacket(packet.get())) {
     LOG(ERROR) << "Format conversion failed.";
   }
 
+  // Get the alpha data if any

[scherkus (not reviewing), 2013/02/22 23:18:01]

nit: I'm sure side data is used for more than just alpha -- I'd rephrase this to
talk about side data and include an example of VP8 alpha

[vignesh, 2013/02/25 21:51:42]

Done.

+  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);
+  buffer = DecoderBuffer::CopyFrom(pkt->data, pkt->size);
+  if (side_data_size) {
+    buffer->SetSideData(side_data, side_data_size);
+  }
   buffer->SetTimestamp(ConvertStreamTimestamp(
       stream_->time_base, packet->pts));
   buffer->SetDuration(ConvertStreamTimestamp(
       stream_->time_base, packet->duration));
   if (buffer->GetTimestamp() != kNoTimestamp() &&
       last_packet_timestamp_ != kNoTimestamp() &&
       last_packet_timestamp_ < buffer->GetTimestamp()) {
     buffered_ranges_.Add(last_packet_timestamp_, buffer->GetTimestamp());
     demuxer_->NotifyBufferingChanged();
   }
@@ skipping 577 matching lines @@
   }
   for (size_t i = 0; i < buffered.size(); ++i)
     host_->AddBufferedTimeRange(buffered.start(i), buffered.end(i));
 }
 
 void FFmpegDemuxer::OnDataSourceError() {
   host_->OnDemuxerError(PIPELINE_ERROR_READ);
 }
 
 }  // namespace media