Interpolate media time for mojo rendering pipeline.

media/mojo/clients/mojo_renderer.cc

Index: media/mojo/clients/mojo_renderer.cc
diff --git a/media/mojo/clients/mojo_renderer.cc b/media/mojo/clients/mojo_renderer.cc
index aea977fa43c37dc9566ce06485204591de5596ff..36690163b3645cf2d89194eda04cb00a24e209e0 100644
--- a/media/mojo/clients/mojo_renderer.cc
+++ b/media/mojo/clients/mojo_renderer.cc
@@ -28,7 +28,8 @@ MojoRenderer::MojoRenderer(
       video_overlay_factory_(std::move(video_overlay_factory)),
       video_renderer_sink_(video_renderer_sink),
       remote_renderer_info_(remote_renderer.PassInterface()),
-      binding_(this) {
+      binding_(this),
+      media_time_interpolator_(&media_clock_) {
   DVLOG(1) << __FUNCTION__;
 }
 
@@ -167,34 +168,47 @@ void MojoRenderer::Flush(const base::Closure& flush_cb) {
     return;
   }
 
+  {
+    base::AutoLock auto_lock(lock_);
+    if (media_time_interpolator_.interpolating())
+      media_time_interpolator_.StopInterpolating();
+  }
+
   flush_cb_ = flush_cb;
   remote_renderer_->Flush(
       base::Bind(&MojoRenderer::OnFlushed, base::Unretained(this)));
 }
 
 void MojoRenderer::StartPlayingFrom(base::TimeDelta time) {
-  DVLOG(2) << __FUNCTION__;
+  DVLOG(2) << __FUNCTION__ << "(" << time << ")";
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(remote_renderer_.is_bound());
 
   {
     base::AutoLock auto_lock(lock_);
-    time_ = time;
+    media_time_interpolator_.SetBounds(time, time, media_clock_.NowTicks());
+    media_time_interpolator_.StartInterpolating();
+    last_media_time_ = base::TimeDelta();
   }
 
   remote_renderer_->StartPlayingFrom(time);
 }
 
 void MojoRenderer::SetPlaybackRate(double playback_rate) {
-  DVLOG(2) << __FUNCTION__;
+  DVLOG(2) << __FUNCTION__ << "(" << playback_rate << ")";
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(remote_renderer_.is_bound());
 
   remote_renderer_->SetPlaybackRate(playback_rate);
+
+  {
+    base::AutoLock auto_lock(lock_);
+    media_time_interpolator_.SetPlaybackRate(playback_rate);
+  }
 }
 
 void MojoRenderer::SetVolume(float volume) {
-  DVLOG(2) << __FUNCTION__;
+  DVLOG(2) << __FUNCTION__ << "(" << volume << ")";
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(remote_renderer_.is_bound());
 
@@ -203,8 +217,15 @@ void MojoRenderer::SetVolume(float volume) {
 
 base::TimeDelta MojoRenderer::GetMediaTime() {
   base::AutoLock auto_lock(lock_);
-  DVLOG(3) << __FUNCTION__ << ": " << time_.InMilliseconds() << " ms";
-  return time_;
+  base::TimeDelta media_time = media_time_interpolator_.GetInterpolatedTime();
+  if (media_time < last_media_time_) {
+    DVLOG(2) << __func__ << ": actual=" << media_time

[alokp, 2016/09/08 17:37:52]

We have the same logic in AudioRendererImpl. In fact I copied this code from
there. Should we move it to PipelineImpl so that they can be shared?

[DaleCurtis, 2016/09/08 17:45:29]

That seems reasonable to me.

[alokp, 2016/09/08 19:30:50]

Done. Please check PipelineImpl and AudioRendererImpl unittests.

+             << " clamped=" << last_media_time_;
+    return last_media_time_;
+  }
+  DVLOG(3) << __FUNCTION__ << ": " << media_time.InMilliseconds() << " ms";
+  last_media_time_ = media_time;
+  return last_media_time_;
 }
 
 bool MojoRenderer::HasAudio() {
@@ -234,12 +255,14 @@ bool MojoRenderer::HasVideo() {
 }
 
 void MojoRenderer::OnTimeUpdate(base::TimeDelta time,
-                                base::TimeDelta max_time) {
-  DVLOG(3) << __FUNCTION__ << ": " << time << ", " << max_time;
+                                base::TimeDelta max_time,
+                                base::TimeTicks capture_time) {
+  DVLOG(4) << __FUNCTION__ << "(" << time << ", " << max_time << ", "
+           << capture_time << ")";
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   base::AutoLock auto_lock(lock_);
-  time_ = time;
+  media_time_interpolator_.SetBounds(time, max_time, capture_time);
 }
 
 void MojoRenderer::OnBufferingStateChange(mojom::BufferingState state) {