Render inband text tracks in the media pipeline

media/filters/ffmpeg_text_decoder.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_FFMPEG_TEXT_DECODER_H_
+#define MEDIA_FILTERS_FFMPEG_TEXT_DECODER_H_
+
+#include <vector>
+
+#include "base/memory/weak_ptr.h"
+#include "media/base/demuxer_stream.h"
+#include "media/base/text_decoder.h"
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace media {
+
+class MEDIA_EXPORT FFmpegTextDecoder : public TextDecoder {
+ public:
+  explicit FFmpegTextDecoder(
+      const scoped_refptr<base::MessageLoopProxy>& message_loop);
+  virtual ~FFmpegTextDecoder();
+
+  // TextDecoder implementation.
+  virtual void Initialize(Demuxer* demuxer) OVERRIDE;
+  virtual void Read(int index, const ReadCB& read_cb) OVERRIDE;
+
+ private:
+  // Callback delivered by the demuxer stream at |index| when
+  // a read from the stream completes.
+  void BufferReady(int index,
+                   DemuxerStream::Status status,
+                   const scoped_refptr<DecoderBuffer>& input);
+
+  scoped_refptr<base::MessageLoopProxy> message_loop_;
+  base::WeakPtrFactory<FFmpegTextDecoder> weak_factory_;
+  base::WeakPtr<FFmpegTextDecoder> weak_this_;
+
+  // All the demuxer streams having type TEXT. The index
+  // position matches its index position in the demuxer.
+  // Index positions of streams that are not TEXT streams
+  // are set to NULL.
+  std::vector<DemuxerStream*> demuxer_streams_;
+
+  // Holds the callbacks for the read requests made by
+  // the downstream text renderer.
+  std::vector<ReadCB> read_callbacks_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(FFmpegTextDecoder);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_FFMPEG_TEXT_DECODER_H_