media/filters/ffmpeg_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_FFMPEG_VIDEO_DECODER_H_
#define MEDIA_FILTERS_FFMPEG_VIDEO_DECODER_H_

#include <list>

#include "base/callback.h"
#include "base/memory/scoped_ptr.h"
#include "media/base/video_decoder.h"
#include "media/base/video_decoder_config.h"
#include "media/base/video_frame_pool.h"
#include "media/ffmpeg/ffmpeg_deleters.h"

struct AVCodecContext;
struct AVFrame;

namespace base {
class SingleThreadTaskRunner;
}

namespace media {

class DecoderBuffer;

class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
 public:
  explicit FFmpegVideoDecoder(
      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
  virtual ~FFmpegVideoDecoder();

  // VideoDecoder implementation.
  virtual void Initialize(const VideoDecoderConfig& config,
                          bool low_delay,
                          const PipelineStatusCB& status_cb) OVERRIDE;
  virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
                      const DecodeCB& decode_cb) OVERRIDE;
  virtual void Reset(const base::Closure& closure) OVERRIDE;
  virtual void Stop() OVERRIDE;

  // Callback called from within FFmpeg to allocate a buffer based on
  // the dimensions of |codec_context|. See AVCodecContext.get_buffer
  // documentation inside FFmpeg.
  int GetVideoBuffer(AVCodecContext *codec_context, AVFrame* frame);

 private:
  enum DecoderState {
    kUninitialized,
    kNormal,
    kFlushCodec,
    kDecodeFinished,
    kError
  };

  // Handles decoding an unencrypted encoded buffer.
  void DecodeBuffer(const scoped_refptr<DecoderBuffer>& buffer);
  bool FFmpegDecode(const scoped_refptr<DecoderBuffer>& buffer,
                    scoped_refptr<VideoFrame>* video_frame);

  // Handles (re-)initializing the decoder with a (new) config.
  // Returns true if initialization was successful.
  bool ConfigureDecoder(bool low_delay);

  // Releases resources associated with |codec_context_| and |av_frame_|
  // and resets them to NULL.
  void ReleaseFFmpegResources();

  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;

  DecoderState state_;

  // TODO(xhwang): Merge DecodeBuffer() into Decode() and remove this.
  DecodeCB decode_cb_;

  // FFmpeg structures owned by this object.
  scoped_ptr<AVCodecContext, ScopedPtrAVFreeContext> codec_context_;
  scoped_ptr<AVFrame, ScopedPtrAVFreeFrame> av_frame_;

  VideoDecoderConfig config_;

  VideoFramePool frame_pool_;

  DISALLOW_COPY_AND_ASSIGN(FFmpegVideoDecoder);
};

}  // namespace media

#endif  // MEDIA_FILTERS_FFMPEG_VIDEO_DECODER_H_