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"
+
+// Include libvpx header files.
+// VPX_CODEC_DISABLE_COMPAT excludes parts of the libvpx API that provide
+// backwards compatibility for legacy applications using the library.
+#define VPX_CODEC_DISABLE_COMPAT 1
+extern "C" {
+#include "third_party/libvpx/source/libvpx/vpx/vpx_decoder.h"
+#include "third_party/libvpx/source/libvpx/vpx/vp8dx.h"
+}
 
 struct vpx_codec_ctx;
 struct vpx_image;
 
 namespace base {
 class MessageLoopProxy;
 }
 
 namespace media {
 
+struct VpxDeleter {
+  inline void operator()(vpx_codec_ctx* ptr) const {
+    if (ptr) {
+      vpx_codec_destroy(ptr);
+      delete ptr;
+    }
+  }
+};
+
 class MEDIA_EXPORT VpxVideoDecoder : public VideoDecoder {
  public:
   explicit VpxVideoDecoder(
       const scoped_refptr<base::MessageLoopProxy>& message_loop);
 
   // VideoDecoder implementation.
   virtual void Initialize(const scoped_refptr<DemuxerStream>& stream,
                           const PipelineStatusCB& status_cb,
                           const StatisticsCB& statistics_cb) OVERRIDE;
   virtual void Read(const ReadCB& read_cb) OVERRIDE;
   virtual void Reset(const base::Closure& closure) OVERRIDE;
   virtual void Stop(const base::Closure& closure) OVERRIDE;
 
  protected:
   virtual ~VpxVideoDecoder();
 
  private:
   enum DecoderState {
     kUninitialized,
     kNormal,
     kFlushCodec,
     kDecodeFinished
   };
 
   // Handles (re-)initializing the decoder with a (new) config.
   // Returns true when initialization was successful.
   bool ConfigureDecoder();
 
-  void CloseDecoder();
   void ReadFromDemuxerStream();
 
   // Carries out the buffer processing operation scheduled by
   // DecryptOrDecodeBuffer().
   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_;
+  scoped_ptr<vpx_codec_ctx, VpxDeleter> vpx_codec_;
+  scoped_ptr<vpx_codec_ctx, VpxDeleter> vpx_codec_alpha_;
 
   DISALLOW_COPY_AND_ASSIGN(VpxVideoDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_VPX_VIDEO_DECODER_H_