Add initial implementation of SourceBufferStream

media/filters/source_buffer_stream.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_SOURCE_BUFFER_STREAM_H_
+#define MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_
+
+#include <deque>
+#include <list>
+#include <utility>
+
+#include "base/memory/ref_counted.h"
+#include "media/base/media_export.h"
+#include "media/base/stream_parser_buffer.h"
+
+namespace media {
+
+class SourceBufferRange;
+
+// SourceBufferStream is a data structure that stores media Buffers in ranges.
+// Buffers can be appended out of presentation order. Buffers are retrieved by
+// seeking to the desired start point and calling GetNextBuffer(). Buffers are
+// returned in sequential presentation order.
+class MEDIA_EXPORT SourceBufferStream {
+ public:
+  typedef std::deque<scoped_refptr<StreamParserBuffer> > BufferQueue;
+  typedef std::pair<base::TimeDelta, base::TimeDelta> Timespan;
+  typedef std::list<Timespan> TimespanList;
+
+  SourceBufferStream();
+  ~SourceBufferStream();
+
+  // Add the |buffers| to the SourceBufferStream. Buffers within the queue are
+  // expected to be in order, but multiple calls to Append() may add buffers out
+  // of order or overlapping. Assumes all buffers within |buffers| are in
+  // presentation order and are non-overlapping.
+  // Returns true if Append() was successful, false if |buffers| are not added.
+  // TODO(vrk): Implement proper end-overlapping. (crbug.com/125072)
+  // This may trigger garbage collection.
+  // TODO(vrk): Implement garbage collection. (crbug.com/125070)
+  bool Append(const BufferQueue& buffers);
+
+  // Changes the SourceBufferStream's state so that it will start returning
+  // buffers starting from the closest keyframe before |timestamp|.
+  void Seek(base::TimeDelta timestamp);
+
+  // Fills |out_buffer| with a new buffer. Seek() must be called before calling
+  // this method. Buffers are presented in order from the last call to Seek().
+  // |out_buffer|'s timestamp may be earlier than the |timestamp| passed to
+  // the last Seek() call.
+  // Returns true if |out_buffer| is filled with a valid buffer, false if
+  // there is not enough data buffered to fulfill the request.
+  bool GetNextBuffer(scoped_refptr<StreamParserBuffer>* out_buffer);
+
+  // Returns a list of the buffered time ranges.
+  TimespanList GetBufferedTime() const;
+
+ private:
+  typedef std::list<SourceBufferRange*> RangeList;
+  // List of disjoint buffered ranges, ordered by start time.
+  RangeList ranges_;
+
+  // True if more data needs to be appended before the Seek() can complete,
+  // false if no Seek() has been requested or the Seek() is completed.
+  bool seek_pending_;
+
+  // Timestamp of the last request to Seek().
+  base::TimeDelta seek_buffer_timestamp_;
+
+  // Pointer to the seeked-to Range. This is the Range from which
+  // GetNextBuffer() calls are fulfilled.
+  SourceBufferRange* selected_range_;
+
+  DISALLOW_COPY_AND_ASSIGN(SourceBufferStream);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_