media: Add support for playback of VP8 Alpha video streams

media/filters/vpx_video_decoder.h

 // 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.
 
 #ifndef MEDIA_FILTERS_VPX_VIDEO_DECODER_H_
 #define MEDIA_FILTERS_VPX_VIDEO_DECODER_H_
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "media/base/demuxer_stream.h"
 #include "media/base/video_decoder.h"
+#include "media/base/video_frame.h"
 
 struct vpx_codec_ctx;
 struct vpx_image;
 
 namespace base {
 class MessageLoopProxy;
 }
 
 namespace media {
 
@@ skipping 33 matching lines @@
   void DoDecryptOrDecodeBuffer(DemuxerStream::Status status,
                                const scoped_refptr<DecoderBuffer>& buffer);
 
   void DecodeBuffer(const scoped_refptr<DecoderBuffer>& buffer);
   bool Decode(const scoped_refptr<DecoderBuffer>& buffer,
               scoped_refptr<VideoFrame>* video_frame);
 
   // Reset decoder and call |reset_cb_|.
   void DoReset();
 
-  void CopyVpxImageTo(const vpx_image* vpx_image,
+  void CopyVpxImageTo(const struct vpx_image* vpx_image,
+                      const struct vpx_image* vpx_image_alpha,
                       scoped_refptr<VideoFrame>* video_frame);
 
   scoped_refptr<base::MessageLoopProxy> message_loop_;
 
   DecoderState state_;
 
   StatisticsCB statistics_cb_;
   ReadCB read_cb_;
   base::Closure reset_cb_;
 
   // Pointer to the demuxer stream that will feed us compressed buffers.
   scoped_refptr<DemuxerStream> demuxer_stream_;
 
   vpx_codec_ctx* vpx_codec_;

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

hmm.. it looks like both of these can use scoped_ptr<T>

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

To do this, the libvpx includes should be moved from to this file from the .cc
file, thereby exposing the libvpx files in the global namespace (this is needed
because the exact type is required at compile time for template expansion). Will
this be fine?

+  vpx_codec_ctx* vpx_codec_alpha_;
+  VideoFrame::Format format_;
 
   DISALLOW_COPY_AND_ASSIGN(VpxVideoDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_VPX_VIDEO_DECODER_H_