MSE: Replace crossfade splicing overlap trimming.

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.
 
 // 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.
 
 #ifndef MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_
@@ skipping 39 matching lines @@
     kEndOfStream
   };
 
   enum Type {
     kAudio,
     kVideo,
     kText
   };
 
   SourceBufferStream(const AudioDecoderConfig& audio_config,
-                     const scoped_refptr<MediaLog>& media_log,
-                     bool splice_frames_enabled);
+                     const scoped_refptr<MediaLog>& media_log);
   SourceBufferStream(const VideoDecoderConfig& video_config,
-                     const scoped_refptr<MediaLog>& media_log,
-                     bool splice_frames_enabled);
+                     const scoped_refptr<MediaLog>& media_log);
   SourceBufferStream(const TextTrackConfig& text_config,
-                     const scoped_refptr<MediaLog>& media_log,
-                     bool splice_frames_enabled);
+                     const scoped_refptr<MediaLog>& media_log);
 
   ~SourceBufferStream();
 
   // Signals that the next buffers appended are part of a new coded frame group
   // starting at |coded_frame_group_start_time|.
   // TODO(acolwell/wolenetz): This should be changed to a presentation
   // timestamp. See http://crbug.com/402502
   void OnStartOfCodedFrameGroup(DecodeTimestamp coded_frame_group_start_time);
 
   // Add the |buffers| to the SourceBufferStream. Buffers within the queue are
@@ skipping 201 matching lines @@
 
   // Searches |ranges_| for the first keyframe timestamp that is >= |timestamp|.
   // If |ranges_| doesn't contain a GOP that covers |timestamp| or doesn't
   // have a keyframe after |timestamp| then kNoTimestamp is returned.
   DecodeTimestamp FindKeyframeAfterTimestamp(const DecodeTimestamp timestamp);
 
   // Returns "VIDEO" for a video SourceBufferStream, "AUDIO" for an audio
   // stream, and "TEXT" for a text stream.
   std::string GetStreamTypeName() const;
 
+  // (Audio only) Pads |new_buffers| with leading silence if start of
+  // |new_buffers| is found to overlap existing buffers. Any overlapped buffer
+  // will later be removed (see PrepareRangesForNextAppend()) and silence is
+  // added to the front of |new_buffers| to make up the gap.
+  void GenerateSpliceSilence(const BufferQueue& new_buffers);
+
   // Returns true if end of stream has been reached, i.e. the
   // following conditions are met:
   // 1. end of stream is marked and there is nothing in the track_buffer.
   // 2. We don't have any ranges, or the last or no range is selected,
   //    or there is a pending seek beyond any existing ranges.
   bool IsEndOfStreamReached() const;
 
   // Deletes the range pointed to by |*itr| and removes it from |ranges_|.
   // If |*itr| points to |selected_range_|, then |selected_range_| is set to
   // NULL. After the range is removed, |*itr| is to the range after the one that
@@ skipping 40 matching lines @@
   Status GetNextBufferInternal(scoped_refptr<StreamParserBuffer>* out_buffer);
 
   // If the next buffer's timestamp is significantly beyond the last output
   // buffer, and if we just exhausted |track_buffer_| on the previous read, this
   // method logs a warning to |media_log_| that there could be perceivable
   // delay. Apps can avoid this behavior by not overlap-appending buffers near
   // current playback position.
   void WarnIfTrackBufferExhaustionSkipsForward(
       const scoped_refptr<StreamParserBuffer>& next_buffer);
 
-  // Called by PrepareRangesForNextAppend() before pruning overlapped buffers to
-  // generate a splice frame with a small portion of the overlapped buffers.  If
-  // a splice frame is generated, the first buffer in |new_buffers| will have
-  // its timestamps, duration, and fade out preroll updated.
-  void GenerateSpliceFrame(const BufferQueue& new_buffers);
-
   // If |out_buffer| has splice buffers or preroll, sets |pending_buffer_|
   // appropriately and returns true.  Otherwise returns false.
   bool SetPendingBuffer(scoped_refptr<StreamParserBuffer>* out_buffer);
 
   // Used to report log messages that can help the web developer figure out what
   // is wrong with the content.
   scoped_refptr<MediaLog> media_log_;
 
   // List of disjoint buffered ranges, ordered by start time.
   RangeList ranges_;
@@ skipping 79 matching lines @@
   // GetNextBufferInternal().
   scoped_refptr<StreamParserBuffer> pending_buffer_;
 
   // Indicates which of the splice buffers in |splice_buffer_| should be
   // handled out next.
   size_t splice_buffers_index_ = 0;
 
   // Indicates that all buffers before |pending_buffer_| have been handed out.
   bool pending_buffers_complete_ = false;
 
-  // Indicates that splice frame generation is enabled.
-  const bool splice_frames_enabled_;
-
   // To prevent log spam, count the number of warnings and successes logged.
-  int num_splice_generation_warning_logs_ = 0;
-  int num_splice_generation_success_logs_ = 0;
+  int num_splice_generation_logs_ = 0;
   int num_track_buffer_gap_warning_logs_ = 0;
   int num_garbage_collect_algorithm_logs_ = 0;
   int num_strange_same_timestamps_logs_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(SourceBufferStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_