Chrome-side implementation of media source timestamp offset

media/filters/chunk_demuxer.cc

Index: media/filters/chunk_demuxer.cc
diff --git a/media/filters/chunk_demuxer.cc b/media/filters/chunk_demuxer.cc
index 06a8d62923e6fa9d98e90db81d32968681a404b6..d90052876629057ed7479e71744afd14efe3ed82 100644
--- a/media/filters/chunk_demuxer.cc
+++ b/media/filters/chunk_demuxer.cc
@@ -99,7 +99,7 @@ static bool IsSupported(const std::string& type,
   *has_audio = false;
   *has_video = false;
 
-  // Search for the SupportedTypeInfo for |type|
+  // Search for the SupportedTypeInfo for |type|.
   for (size_t i = 0; i < arraysize(kSupportedTypeInfo); ++i) {
     const SupportedTypeInfo& type_info = kSupportedTypeInfo[i];
     if (type == type_info.type) {
@@ -465,6 +465,20 @@ void ChunkDemuxerStream::CreateReadDoneClosures_Locked(ClosureQueue* closures) {
   }
 }
 
+void ChunkDemuxer::AdjustBufferTimestamps(
+    const StreamParser::BufferQueue& buffers,
+    base::TimeDelta timestamp_offset) {
+  if (timestamp_offset == base::TimeDelta())
+    return;
+
+  for (StreamParser::BufferQueue::const_iterator itr = buffers.begin();
+       itr != buffers.end(); ++itr) {
+    (*itr)->SetDecodeTimestamp(
+        (*itr)->GetDecodeTimestamp() + timestamp_offset);
+    (*itr)->SetTimestamp((*itr)->GetTimestamp() + timestamp_offset);
+  }
+}
+
 ChunkDemuxer::ChunkDemuxer(ChunkDemuxerClient* client)
     : state_(WAITING_FOR_INIT),
       host_(NULL),
@@ -611,9 +625,13 @@ ChunkDemuxer::Status ChunkDemuxer::AddId(const std::string& id,
       audio_cb,
       video_cb,
       base::Bind(&ChunkDemuxer::OnNeedKey, base::Unretained(this)),
-      base::Bind(&ChunkDemuxer::OnNewMediaSegment, base::Unretained(this), id));
+      base::Bind(&ChunkDemuxer::OnNewMediaSegment, base::Unretained(this), id),
+      base::Bind(&ChunkDemuxer::OnEndOfMediaSegment,
+                 base::Unretained(this), id));
 
   stream_parser_map_[id] = stream_parser.release();
+  StreamInfo info = { base::TimeDelta(), true };
+  stream_info_map_[id] = info;
 
   return kOk;
 }
@@ -624,6 +642,7 @@ void ChunkDemuxer::RemoveId(const std::string& id) {
 
   delete stream_parser_map_[id];
   stream_parser_map_.erase(id);
+  stream_info_map_.erase(id);
 
   if (source_id_audio_ == id && audio_)
     audio_->Shutdown();
@@ -759,6 +778,20 @@ void ChunkDemuxer::Abort(const std::string& id) {
   stream_parser_map_[id]->Flush();
 }
 
+bool ChunkDemuxer::TimestampOffset(const std::string& id, float offset) {
+  DVLOG(1) << "TimestampOffset(" << id << ", " << offset << ")";
+  DCHECK_GT(stream_parser_map_.count(id), 0u);
+
+  TimeDelta time_offset = TimeDelta::FromMicroseconds(
+      offset * base::Time::kMicrosecondsPerSecond);
+
+  if (!stream_info_map_[id].can_update_offset)
+    return false;
+
+  stream_info_map_[id].timestamp_offset = time_offset;
+  return true;
+}
+
 bool ChunkDemuxer::EndOfStream(PipelineStatus status) {
   DVLOG(1) << "EndOfStream(" << status << ")";
   base::AutoLock auto_lock(lock_);
@@ -963,6 +996,11 @@ bool ChunkDemuxer::OnAudioBuffers(const StreamParser::BufferQueue& buffers) {
   if (!audio_)
     return false;
 
+  CHECK_GT(stream_info_map_.count(source_id_audio_), 0u);
+  AdjustBufferTimestamps(
+      buffers, stream_info_map_[source_id_audio_].timestamp_offset);
+  stream_info_map_[source_id_video_].can_update_offset = false;

[acolwell GONE FROM CHROMIUM, 2012/07/20 18:21:01]

did you mean source_id_audio_ here?

[vrk (LEFT CHROMIUM), 2012/07/25 17:16:48]

d'oh. Yes :) My test page only uses video, so I didn't catch this!

I actually removed this line in response to the comment below, but the unit
tests I added catches the equivalent mistake.

+
   return audio_->Append(buffers);
 }
 
@@ -973,6 +1011,11 @@ bool ChunkDemuxer::OnVideoBuffers(const StreamParser::BufferQueue& buffers) {
   if (!video_)
     return false;
 
+  CHECK_GT(stream_info_map_.count(source_id_video_), 0u);
+  AdjustBufferTimestamps(
+      buffers, stream_info_map_[source_id_video_].timestamp_offset);
+  stream_info_map_[source_id_video_].can_update_offset = false;

[acolwell GONE FROM CHROMIUM, 2012/07/20 18:21:01]

Perhaps move this to OnNewMediaSegment()? That way it is symmetrical with
OnEndOfMediaSegment().

[vrk (LEFT CHROMIUM), 2012/07/25 17:16:48]

Done and removed from OnAudioBuffers() as well.

+
   return video_->Append(buffers);
 }
 
@@ -983,11 +1026,15 @@ bool ChunkDemuxer::OnNeedKey(scoped_array<uint8> init_data,
 }
 
 void ChunkDemuxer::OnNewMediaSegment(const std::string& source_id,
-                                     TimeDelta start_timestamp) {
+                                     TimeDelta timestamp) {
   DVLOG(2) << "OnNewMediaSegment(" << source_id << ", "
-           << start_timestamp.InSecondsF() << ")";
+           << timestamp.InSecondsF() << ")";
   lock_.AssertAcquired();
 
+  CHECK_GT(stream_info_map_.count(source_id), 0u);
+  base::TimeDelta start_timestamp =
+      timestamp + stream_info_map_[source_id].timestamp_offset;
+
   if (start_time_ == kNoTimestamp()) {
     DCHECK(state_ == INITIALIZING || state_ == WAITING_FOR_START_TIME);
     // Use the first reported media segment start time as the |start_time_|
@@ -1017,4 +1064,10 @@ void ChunkDemuxer::OnNewMediaSegment(const std::string& source_id,
   base::ResetAndReturn(&init_cb_).Run(PIPELINE_OK);
 }
 
+void ChunkDemuxer::OnEndOfMediaSegment(const std::string& source_id) {
+  DVLOG(2) << "OnEndOfMediaSegment(" << source_id << ")";
+  CHECK_GT(stream_info_map_.count(source_id_video_), 0u);
+  stream_info_map_[source_id_video_].can_update_offset = true;
+}
+
 }  // namespace media