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);
+  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]->GetSpliceBufferConfigId(0);
+}
+
+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;

[wolenetz, 2016/07/25 21:49:02]

What if the buffer at this time contains splice buffers with differing config
IDs? Also note that the splice buffers' decode comes before this time, in
reality, in part to support preroll of cross-fade IIUC. Please document intent
for these methods -- would really help review.

[chcunningham, 2016/12/01 17:07:16]

Splicing is gone. Now just checking the config ID on the buffer itself.

[wolenetz, 2016/12/02 00:18:49]

Acknowledged.

+
+  KeyframeMap::const_iterator result = GetFirstKeyframeAtOrBefore(start);
+  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]->GetSpliceBufferConfigId(0);
+  buffer_index++;
+  while (buffer_index < buffers_.size() &&
+         buffers_[buffer_index]->GetDecodeTimestamp() <= end) {
+    if (buffers_[buffer_index]->GetSpliceBufferConfigId(0) != start_config)

[wolenetz, 2016/07/25 21:49:02]

Ditto: if there is a splice buffer, it/they could have different config ID than
the buffer at buffers_[buffer_index]

[chcunningham, 2016/12/01 17:07:16]

Ditto.

[wolenetz, 2016/12/02 00:18:49]

Acknowledged.

+      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