Introduce some buffering into the cast media pipeline.

chromecast/media/cma/base/buffering_frame_provider.h

+// Copyright 2014 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 CHROMECAST_MEDIA_CMA_BASE_BUFFERING_FRAME_PROVIDER_H_
+#define CHROMECAST_MEDIA_CMA_BASE_BUFFERING_FRAME_PROVIDER_H_
+
+#include <list>
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "chromecast/media/cma/base/coded_frame_provider.h"
+#include "media/base/audio_decoder_config.h"
+#include "media/base/video_decoder_config.h"
+
+namespace chromecast {
+namespace media {
+class DecoderBufferBase;
+
+// BufferingFrameProvider -
+// Fetch some data from another CodedFrameProvider up to a certain size limit.
+class BufferingFrameProvider : public CodedFrameProvider {
+ public:
+  typedef base::Callback<void(const scoped_refptr<DecoderBufferBase>&, bool)>
+      FrameBufferedCB;
+
+  // Creates a frame provider that buffers coded frames up to the
+  // |max_buffer_size| limit (given as a number of bytes).
+  // |max_frame_size| corresponds to an upper bound of the expected frame size.
+  // Each time a frame is buffered, |frame_buffered_cb| is invoked with the
+  // last frame buffered. The second parameter of the callback indicates
+  // whether the maximum capacity has been reached, i.e. whether the next frame
+  // size might overflow the buffer: |total_buffer_size_| + next_frame_size
+  // might be greater than |max_buffer_size|.
+  // Note: takes ownership of |coded_frame_provider|.
+  BufferingFrameProvider(
+      scoped_ptr<CodedFrameProvider> coded_frame_provider,
+      size_t max_buffer_size,
+      size_t max_frame_size,
+      const FrameBufferedCB& frame_buffered_cb);
+  virtual ~BufferingFrameProvider();
+
+  // CodedFrameProvider implementation.
+  virtual void Read(const ReadCB& read_cb) OVERRIDE;
+  virtual void Flush(const base::Closure& flush_cb) OVERRIDE;
+
+ private:
+  class BufferWithConfig {
+   public:
+    BufferWithConfig(
+        const scoped_refptr<DecoderBufferBase>& buffer,
+        const ::media::AudioDecoderConfig& audio_config,
+        const ::media::VideoDecoderConfig& video_config);
+    ~BufferWithConfig();
+
+    const scoped_refptr<DecoderBufferBase>& buffer() const { return buffer_; }
+    const ::media::AudioDecoderConfig& audio_config() const {
+      return audio_config_;
+    }
+    const ::media::VideoDecoderConfig& video_config() const {
+      return video_config_;
+    }
+
+   private:
+    scoped_refptr<DecoderBufferBase> buffer_;
+    ::media::AudioDecoderConfig audio_config_;
+    ::media::VideoDecoderConfig video_config_;
+  };
+
+  void OnNewBuffer(const scoped_refptr<DecoderBufferBase>& buffer,
+                   const ::media::AudioDecoderConfig& audio_config,
+                   const ::media::VideoDecoderConfig& video_config);
+  void RequestBufferIfNeeded();
+  void CompleteReadIfNeeded();
+
+  base::ThreadChecker thread_checker_;
+
+  // Frame provider the buffering frame provider fetches data from.
+  scoped_ptr<CodedFrameProvider> coded_frame_provider_;
+
+  // Indicates whether there is a pending read request on
+  // |coded_frame_provider_|.
+  bool is_pending_request_;
+
+  // Indicates whether the end of stream has been reached.
+  bool is_eos_;
+
+  std::list<BufferWithConfig> buffer_list_;
+
+  // Size in bytes of audio/video buffers in |buffer_list_|.
+  size_t total_buffer_size_;
+
+  // Max amount of data to buffer.
+  // i.e. this is the maximum size of buffers in |buffer_list_|.
+  const size_t max_buffer_size_;
+
+  // Maximum expected frame size.
+  const size_t max_frame_size_;
+
+  // Callback invoked each time there is a new frame buffered.
+  FrameBufferedCB frame_buffered_cb_;
+
+  // Pending read callback.
+  ReadCB read_cb_;
+
+  scoped_ptr<base::WeakPtrFactory<BufferingFrameProvider> > weak_factory_;
+  base::WeakPtr<BufferingFrameProvider> weak_this_;
+
+  DISALLOW_COPY_AND_ASSIGN(BufferingFrameProvider);
+};
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_MEDIA_CMA_BASE_BUFFERING_FRAME_PROVIDER_H_