Implement start, end, and middle overlaps for 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>
@@ skipping 17 matching lines @@
   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;
 
+  // Appends |new_buffers| into |range_for_new_buffers_itr|, handling start and
+  // end overlaps if necessary.
+  void InsertIntoExistingRange(
+      const RangeList::iterator& range_for_new_buffers_itr,
+      const BufferQueue& new_buffers);
+
   // Resolve overlapping ranges such that no ranges overlap anymore.
-  // |range_itr| points to the iterator in |ranges_| immediately after
-  // |new_range|. Returns the iterator in |ranges_| immediately after
-  // |new_range|, which may be different from the original |range_itr|.
-  RangeList::iterator ResolveCompleteOverlaps(
-      const RangeList::iterator& range_itr, SourceBufferRange* new_range);
-  RangeList::iterator ResolveEndOverlaps(
-      const RangeList::iterator& range_itr, SourceBufferRange* new_range);
+  // |range_with_new_buffers_itr| points to the range that has newly appended
+  // buffers.
+  void ResolveCompleteOverlaps(
+      const RangeList::iterator& range_with_new_buffers_itr);
+  void ResolveEndOverlap(const RangeList::iterator& range_with_new_buffers_itr);
 
-  // Checks to see if the range pointed to by |range_itr| can be appended to the
-  // end of |new_range|, and if so, appends the range and updates |ranges_| to
-  // reflect this.
+  // Adds buffers to |track_buffer_| and updates |selected_range_| accordingly.
+  // |range_with_new_buffers_itr| points to the range containing the newly
+  // appended buffers.
+  // |deleted_buffers| contains all the buffers that were deleted as a result
+  // of appending new buffers into |range_with_new_buffers_itr|. |next_buffer|
+  // points to the next buffer in |deleted_buffers| that was deleted. Assumes

[acolwell GONE FROM CHROMIUM, 2012/05/22 19:35:23]

The "that was deleted" here confuses me. I don't really understand what you are
trying to say here. Is this the next buffer that should be returned from
GetNextBuffer()?

[vrk (LEFT CHROMIUM), 2012/05/24 20:06:30]

Yeah sorry, I didn't know how to describe this without using
|next_buffer_index_|! But "next buffer to be returned from GetNextBuffer()"
sounds good. Reworded comment!

+  // |deleted_buffers| and |next_buffer| are valid.
+  void UpdateTrackBuffer(
+      const RangeList::iterator& range_with_new_buffers_itr,
+      const BufferQueue& deleted_buffers,
+      const BufferQueue::iterator& next_buffer);
+
+  // Checks to see if |range_with_new_buffers_itr| can be merged with the range
+  // next to it, and merges them if so.
   void MergeWithAdjacentRangeIfNecessary(
-      const RangeList::iterator& range_itr, SourceBufferRange* new_range);
+      const RangeList::iterator& range_with_new_buffers_itr);
 
   // 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 after the |track_buffer_| has been
   // emptied.
   SourceBufferRange* selected_range_;
 
   // Queue of the next buffers to be returned from calls to GetNextBuffer(). If
   // |track_buffer_| is empty, return buffers from |selected_range_|.
   BufferQueue track_buffer_;
 
-  // True if the next buffer after the end of the |track_buffer_| is not
-  // buffered yet and we need to wait for the next keyframe after
-  // |track_buffer_| to be appended.
-  bool waiting_for_keyframe_;
-
   DISALLOW_COPY_AND_ASSIGN(SourceBufferStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_