Chrome-side implementation of media source timestamp offset

media/webm/webm_cluster_parser.cc

 // 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.
 
 #include "media/webm/webm_cluster_parser.h"
 
 #include "base/logging.h"
 #include "media/base/data_buffer.h"
 #include "media/base/decrypt_config.h"
 #include "media/webm/webm_constants.h"
@@ skipping 57 matching lines @@
     // call.
     parser_.Reset();
 
     last_block_timecode_ = -1;
     cluster_timecode_ = -1;
   }
 
   return result;
 }
 
+void WebMClusterParser::SetTimestampOffset(base::TimeDelta offset) {
+  timestamp_offset_ = offset;
+}
+
+void WebMClusterParser::ClearTimestampOffset() {
+  SetTimestampOffset(base::TimeDelta());
+}
+
 WebMParserClient* WebMClusterParser::OnListStart(int id) {
   if (id == kWebMIdCluster) {
     cluster_timecode_ = -1;
     cluster_start_time_ = kNoTimestamp();
   } else if (id == kWebMIdBlockGroup) {
     block_data_.reset();
     block_data_size_ = -1;
     block_duration_ = -1;
   }
 
@@ skipping 96 matching lines @@
   }
 
   if (last_block_timecode_ != -1 && timecode < last_block_timecode_) {
     DVLOG(1) << "Got a block with a timecode before the previous block.";
     return false;
   }
 
   last_block_timecode_ = timecode;
 
   base::TimeDelta timestamp = base::TimeDelta::FromMicroseconds(
-      (cluster_timecode_ + timecode) * timecode_multiplier_);
+      (cluster_timecode_ + timecode) * timecode_multiplier_) +
+      timestamp_offset_;
 
   // The first bit of the flags is set when the block contains only keyframes.
   // http://www.matroska.org/technical/specs/index.html
   bool is_keyframe = (flags & 0x80) != 0;
   scoped_refptr<StreamParserBuffer> buffer =
       StreamParserBuffer::CopyFrom(data, size, is_keyframe);
 
   if (track_num == video_.track_num() && video_encryption_key_id_.get()) {
     buffer->SetDecryptConfig(scoped_ptr<DecryptConfig>(new DecryptConfig(
         video_encryption_key_id_.get(), video_encryption_key_id_size_)));
@@ skipping 34 matching lines @@
 
   buffers_.push_back(buffer);
   return true;
 }
 
 void WebMClusterParser::Track::Reset() {
   buffers_.clear();
 }
 
 }  // namespace media