Preliminary change for new rtc rendering algorithm

content/renderer/media/webrtc/media_stream_remote_video_source.cc

Index: content/renderer/media/webrtc/media_stream_remote_video_source.cc
diff --git a/content/renderer/media/webrtc/media_stream_remote_video_source.cc b/content/renderer/media/webrtc/media_stream_remote_video_source.cc
index e81b37701de15df10019bdf517c105cdc50cffef..8e3ac3c7ad3dab5ec69b047727d8c75c66eaa232 100644
--- a/content/renderer/media/webrtc/media_stream_remote_video_source.cc
+++ b/content/renderer/media/webrtc/media_stream_remote_video_source.cc
@@ -62,7 +62,7 @@ RemoteVideoSourceDelegate::~RemoteVideoSourceDelegate() {
 
 void MediaStreamRemoteVideoSource::RemoteVideoSourceDelegate::RenderFrame(
     const cricket::VideoFrame* incoming_frame) {
-  TRACE_EVENT0("webrtc", "RemoteVideoSourceDelegate::RenderFrame");
+  TRACE_EVENT_BEGIN0("webrtc", "RemoteVideoSourceDelegate::RenderFrame");

[DaleCurtis, 2015/07/31 17:48:27]

Ditto.

[qiangchen, 2015/07/31 20:06:07]

Done.

   base::TimeDelta timestamp = base::TimeDelta::FromMicroseconds(
       incoming_frame->GetElapsedTime() / rtc::kNumNanosecsPerMicrosec);
 
@@ -96,6 +96,15 @@ void MediaStreamRemoteVideoSource::RemoteVideoSourceDelegate::RenderFrame(
         base::Bind(&base::DeletePointer<cricket::VideoFrame>, frame->Copy()));
   }
 
+  base::TimeTicks render_time =
+      base::TimeTicks::FromInternalValue(incoming_frame->GetTimeStamp() / 1000);

[DaleCurtis, 2015/07/31 17:48:27]

This still isn't correct unless the value returned by GetTimeStamp is based on
the same clock as base::TimeTicks::Now().  Even then you should instead use
base::TimeTicks() + base::TimeDelta::FromMicroseconds() then.

[qiangchen, 2015/07/31 20:06:07]

This is a good point. The timestamp is from WebRTC, essentially
webrtc::TickTime::Now(), is that the same with base::TimeTicks::Now()? In my
testing, they are the same, but I'm not sure whether this may be platform
specific. Or is it better to do a re-alignment here?

[DaleCurtis, 2015/08/03 21:08:04]

If they're the same then using FromMicroseconds() + base::TimeTicks() is okay,
but you should be sure they are the same -- otherwise yes you should do a
realignment before exposing it outside of WebRTC like this.

+  video_frame->metadata()->SetTimeTicks(
+      media::VideoFrameMetadata::REFERENCE_TIME,
+      render_time);
+
+  TRACE_EVENT_END1("webrtc", "RemoteVideoSourceDelegate::RenderFrame",
+                   "Ideal Render Instant", render_time.ToInternalValue());
+
   io_task_runner_->PostTask(
       FROM_HERE, base::Bind(&RemoteVideoSourceDelegate::DoRenderFrameOnIOThread,
                             this, video_frame));