Introduce VideoFrameStream, the video frame provider in media pipeline.

media/filters/video_frame_stream.h

+// Copyright (c) 2013 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_VIDEO_FRAME_STREAM_H_
+#define MEDIA_FILTERS_VIDEO_FRAME_STREAM_H_
+
+#include <list>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "media/base/decryptor.h"
+#include "media/base/media_export.h"
+#include "media/base/pipeline_status.h"
+#include "media/base/video_decoder.h"
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace media {
+
+class DecryptingDemuxerStream;
+class DemuxerStream;
+class VideoDecoderSelector;
+
+// Wraps a DemuxerStream and a list of VideoDecoders and provides decoded
+// VideoFrames to its client (e.g. VideoRendererBase).
+class MEDIA_EXPORT VideoFrameStream {
+ public:
+  typedef std::list<scoped_refptr<VideoDecoder> > VideoDecoderList;
+
+  // Indicates completion of VideoFrameStream initialization.
+  typedef base::Callback<void(bool success, bool has_alpha)> InitCB;
+
+  VideoFrameStream(const scoped_refptr<base::MessageLoopProxy>& message_loop,
+                   const SetDecryptorReadyCB& set_decryptor_ready_cb);
+
+  ~VideoFrameStream();
+
+  // Initializes the VideoFrameStream and returns the initialization result
+  // through |init_cb|. Note that |init_cb| is always called asynchronously.
+  void Initialize(const scoped_refptr<DemuxerStream>& stream,
+                  const VideoDecoderList& decoders,
+                  const StatisticsCB& statistics_cb,
+                  const InitCB& init_cb);
+
+  // Reads a decoded VideoFrame and returns it via the |read_cb|. Note that
+  // |read_cb| is always called asynchronously. This method should only be
+  // called after initialization has succeeded and must not be called during
+  // any pending Reset() and/or Stop().
+  void ReadFrame(const VideoDecoder::ReadCB& read_cb);

[xhwang, 2013/03/21 01:10:17]

I didn't use Read() on purpose because in the next CL VFS will implement
DemuxerStream which has an API Read().

+
+  // Resets the decoder, flushes all decoded frames and/or internal buffers,
+  // fires any existing pending read callback and calls |closure| on completion.
+  // Note that |closure| is always called asynchronously. This method should
+  // only be called after initialization has succeeded and must not be called
+  // during any pending Reset() and/or Stop().
+  void Reset(const base::Closure& closure);
+
+  // Stops the decoder, fires any existing pending read callback or reset
+  // callback and calls |closure| on completion. Note that |closure| is always
+  // called asynchronously. The VideoFrameStream cannot be used anymore after
+  // it is stopped. This method can be called at any time but not during another
+  // pending Stop().
+  void Stop(const base::Closure& closure);
+
+ private:
+  enum State {
+    UNINITIALIZED,
+    NORMAL,
+    STOPPED
+  };
+
+  // Called when |decoder_selector_| selected the |selected_decoder|.
+  // |decrypting_demuxer_stream| was also populated if a DecryptingDemuxerStream
+  // is created to help decrypt the encrypted stream.
+  // Note: |decoder_selector| is passed here to keep the VideoDecoderSelector
+  // alive until OnDecoderSelected() finishes.
+  void OnDecoderSelected(
+      scoped_ptr<VideoDecoderSelector> decoder_selector,
+      const scoped_refptr<VideoDecoder>& selected_decoder,
+      const scoped_refptr<DecryptingDemuxerStream>& decrypting_demuxer_stream);
+
+  // Callback for VideoDecoder::Read().
+  void OnFrameRead(const VideoDecoder::Status status,
+                   const scoped_refptr<VideoFrame>& frame);
+
+  void ResetDecoder();
+  // Callback for VideoDecoder::Reset().
+  void OnDecoderReset();
+
+  void StopDecoder();
+  // Callback for VideoDecoder::Stop().
+  void OnDecoderStopped();
+
+  scoped_refptr<base::MessageLoopProxy> message_loop_;
+  base::WeakPtrFactory<VideoFrameStream> weak_factory_;
+  base::WeakPtr<VideoFrameStream> weak_this_;
+
+  State state_;
+
+  InitCB init_cb_;
+  VideoDecoder::ReadCB read_cb_;
+  base::Closure reset_cb_;
+  base::Closure stop_cb_;
+
+  SetDecryptorReadyCB set_decryptor_ready_cb_;
+
+  // These two will be set by VideoDecoderSelector::SelectVideoDecoder().
+  scoped_refptr<VideoDecoder> decoder_;
+  scoped_refptr<DecryptingDemuxerStream> decrypting_demuxer_stream_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameStream);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_VIDEO_FRAME_STREAM_H_