Bug Fix: Remote Video Hang For Apprtc Loopback

content/renderer/media/webmediaplayer_ms_compositor.cc

 // Copyright 2015 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 "content/renderer/media/webmediaplayer_ms_compositor.h"
 
 #include <stdint.h>
 
 #include "base/command_line.h"
 #include "base/hash.h"
@@ skipping 167 matching lines @@
   if (video_frame_provider_client_ && !stopped_)
     video_frame_provider_client_->StartRendering();
 }
 
 void WebMediaPlayerMSCompositor::EnqueueFrame(
     const scoped_refptr<media::VideoFrame>& frame) {
   DCHECK(thread_checker_.CalledOnValidThread());
   base::AutoLock auto_lock(current_frame_lock_);
   ++total_frame_count_;
 
+  // With algorithm off, just let |current_frame_| hold the incoming |frame|.
   if (!rendering_frame_buffer_) {
     SetCurrentFrame(frame);
     return;
   }
 
   // This is a signal frame saying that the stream is stopped.
   bool end_of_stream = false;
   if (frame->metadata()->GetBoolean(media::VideoFrameMetadata::END_OF_STREAM,
                                     &end_of_stream) &&
       end_of_stream) {
     rendering_frame_buffer_.reset();
     SetCurrentFrame(frame);
     return;
   }
 
+  // If we detect a bad frame without |render_time|, we switch off algorithm,
+  // because without |render_time|, algorithm cannot work.
+  // In general, this should not happen.
   base::TimeTicks render_time;
   if (!frame->metadata()->GetTimeTicks(
           media::VideoFrameMetadata::REFERENCE_TIME, &render_time)) {
     DLOG(WARNING)
         << "Incoming VideoFrames have no REFERENCE_TIME, switching off super "
            "sophisticated rendering algorithm";
     rendering_frame_buffer_.reset();
     SetCurrentFrame(frame);
     return;
   }
 
+  // This block considers the case that vsyncs stops rendering frames.

[DaleCurtis, 2016/03/09 21:54:01]

"The code below handles the case where UpdateCurrentFrame() callbacks stop.
These callbacks can stop when the tab is hidden or the page area containing the
video frame is scrolled out of view. Since some hardware decoders only have a
limited number of output frames, we must aggressively release frames in this
case."

[qiangchen, 2016/03/09 22:46:40]

Done.

+  // A probable cause is that the tab is inactive.
+  // Nevertheless we still have to let old frames go.
+  const base::TimeTicks now = base::TimeTicks::Now();
+  if (now > last_deadline_max_ && current_frame_) {
+    dropped_frame_count_ += rendering_frame_buffer_->frames_queued() - 1;

[DaleCurtis, 2016/03/09 21:54:01]

Add a comment explaining why the -1.

[qiangchen, 2016/03/09 22:46:40]

Done.

+    rendering_frame_buffer_->Reset();
+    timestamps_to_clock_times_.clear();
+    SetCurrentFrame(frame);
+  }
+
   timestamps_to_clock_times_[frame->timestamp()] = render_time;
-
   rendering_frame_buffer_->EnqueueFrame(frame);
-
-  const base::TimeTicks now = base::TimeTicks::Now();
-  if (now <= last_deadline_max_)
-    return;
-
-  // This shows vsyncs stops rendering frames. A probable cause is that the
-  // tab is not in the front. But we still have to let old frames go.
-  const base::TimeTicks deadline_max =
-      std::max(now, last_deadline_max_ + last_render_length_);
-
-  Render(deadline_max - last_render_length_, deadline_max);
 }
 
 bool WebMediaPlayerMSCompositor::UpdateCurrentFrame(
     base::TimeTicks deadline_min,
     base::TimeTicks deadline_max) {
   DCHECK(compositor_task_runner_->BelongsToCurrentThread());
 
   TRACE_EVENT_BEGIN2("webrtc", "WebMediaPlayerMS::UpdateCurrentFrame",
                      "Actual Render Begin", deadline_min.ToInternalValue(),
                      "Actual Render End", deadline_max.ToInternalValue());
@@ skipping 153 matching lines @@
   }
 
   if (!rendering_frame_buffer_) {
     rendering_frame_buffer_.reset(new media::VideoRendererAlgorithm(
         base::Bind(&WebMediaPlayerMSCompositor::MapTimestampsToRenderTimeTicks,
                    base::Unretained(this))));
   }
 }
 
 }  // namespace content