Implement opus seek preroll for MediaSourceExtensions.

media/filters/source_buffer_range.h

 // Copyright 2014 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_RANGE_H_
 #define MEDIA_FILTERS_SOURCE_BUFFER_RANGE_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 19 matching lines @@
 
   // Policy for handling large gaps between buffers. Continuous media like
   // audio & video should use NO_GAPS_ALLOWED. Discontinuous media like
   // timed text should use ALLOW_GAPS because large differences in timestamps
   // are common and acceptable.
   enum GapPolicy {
     NO_GAPS_ALLOWED,
     ALLOW_GAPS
   };
 
+  // Return the config ID for the buffer at |timestamp|. Precondition: callers
+  // must first verify CanSeekTo(timestamp) == true.
+  int GetConfigIdAtTime(DecodeTimestamp timestamp);
+
+  // Return true if all buffers in range of [start, end] have the same config
+  // ID. Precondition: callers must first verify that
+  // CanSeekTo(start) ==  CanSeekTo(end) == true.
+  bool SameConfigThruRange(DecodeTimestamp start, DecodeTimestamp end);
+
   // Sequential buffers with the same decode timestamp make sense under certain
   // conditions, typically when the first buffer is a keyframe. Due to some
   // atypical media append behaviors where a new keyframe might have the same
   // timestamp as a previous non-keyframe, the playback of the sequence might
   // involve some throwaway decode work. This method supports detecting this
   // situation so that callers can log warnings (it returns true in this case
   // only).
   // For all other cases, including more typical same-DTS sequences, this method
   // returns false. Examples of typical situations where DTS of two consecutive
   // frames can be equal:
@@ skipping 266 matching lines @@
 
   // Stores the amount of memory taken up by the data in |buffers_|.
   size_t size_in_bytes_;
 
   DISALLOW_COPY_AND_ASSIGN(SourceBufferRange);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_SOURCE_BUFFER_RANGE_H_