Implement opus seek preroll for MediaSourceExtensions.

media/filters/source_buffer_range.cc

 // 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.
 
 #include "media/filters/source_buffer_range.h"
 
 #include <algorithm>
 
 #include "media/base/timestamp_constants.h"
 
@@ skipping 88 matching lines @@
 void SourceBufferRange::Seek(DecodeTimestamp timestamp) {
   DCHECK(CanSeekTo(timestamp));
   DCHECK(!keyframe_map_.empty());
 
   KeyframeMap::iterator result = GetFirstKeyframeAtOrBefore(timestamp);
   next_buffer_index_ = result->second - keyframe_map_index_base_;
   CHECK_LT(next_buffer_index_, static_cast<int>(buffers_.size()))
       << next_buffer_index_ << ", size = " << buffers_.size();
 }
 
+int SourceBufferRange::GetConfigIdAtTime(DecodeTimestamp timestamp) {
+  DCHECK(CanSeekTo(timestamp));
+  DCHECK(!keyframe_map_.empty());
+
+  KeyframeMap::iterator result = GetFirstKeyframeAtOrBefore(timestamp);
+  CHECK(result != keyframe_map_.end());
+  size_t buffer_index = result->second - keyframe_map_index_base_;
+  CHECK_LT(buffer_index, buffers_.size()) << buffer_index
+                                          << ", size = " << buffers_.size();
+
+  return buffers_[buffer_index]->GetConfigId();
+}
+
+bool SourceBufferRange::SameConfigThruRange(DecodeTimestamp start,
+                                            DecodeTimestamp end) {
+  DCHECK(CanSeekTo(start));
+  DCHECK(CanSeekTo(end));
+  DCHECK(start <= end);
+  DCHECK(!keyframe_map_.empty());
+
+  if (start == end)
+    return true;
+
+  KeyframeMap::const_iterator result = GetFirstKeyframeAtOrBefore(start);
+  CHECK(result != keyframe_map_.end());
+  size_t buffer_index = result->second - keyframe_map_index_base_;
+  CHECK_LT(buffer_index, buffers_.size()) << buffer_index
+                                          << ", size = " << buffers_.size();
+
+  int start_config = buffers_[buffer_index]->GetConfigId();
+  buffer_index++;
+  while (buffer_index < buffers_.size() &&
+         buffers_[buffer_index]->GetDecodeTimestamp() <= end) {
+    if (buffers_[buffer_index]->GetConfigId() != start_config)
+      return false;
+    buffer_index++;
+  }
+
+  return true;
+}
+
 void SourceBufferRange::SeekAheadTo(DecodeTimestamp timestamp) {
   SeekAhead(timestamp, false);
 }
 
 void SourceBufferRange::SeekAheadPast(DecodeTimestamp timestamp) {
   SeekAhead(timestamp, true);
 }
 
 void SourceBufferRange::SeekAhead(DecodeTimestamp timestamp,
                                   bool skip_given_timestamp) {
@@ skipping 516 matching lines @@
     }
 
     if (buffer->timestamp() + buffer->duration() <= start.ToPresentationTime())
       continue;
     buffers->push_back(buffer);
   }
   return previous_size < buffers->size();
 }
 
 }  // namespace media