Render inband text tracks in the media pipeline

media/base/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_BASE_TEXT_DECODER_H_
+#define MEDIA_BASE_TEXT_DECODER_H_
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+class DemuxerStream;
+class TextCue;
+
+class MEDIA_EXPORT TextDecoder {
+ public:
+  TextDecoder();
+  virtual ~TextDecoder();
+
+  // Initialize a TextDecoder from the text streams from the given demuxer.
+  virtual void Initialize() = 0;
+
+  // Request frame from the given demuxer text stream, to be decoded and
+  // returned as a text track cue via the provided callback. Only one read
+  // per demuxer stream may be in flight at any given time.
+  //
+  // Implementations guarantee that the callback will not be called from within
+  // this method.
+  //
+  // A non-NULL text buffer pointer will contain a decoded text track cue.
+  // A NULL buffer pointer indicates end-of-stream, or error.
+  typedef base::Callback<void(DemuxerStream*,
+                              const scoped_refptr<TextCue>&)> ReadCB;
+  virtual void Read(DemuxerStream* stream, const ReadCB& read_cb) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TextDecoder);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_TEXT_DECODER_H_