MediaStreamRemoteVideoSource: Remove dependency to cricket::VideoFrame::GetElapsedTime()

content/renderer/media/webrtc/media_stream_remote_video_source.cc

 // Copyright 2014 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/webrtc/media_stream_remote_video_source.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/threading/thread_checker.h"
 #include "base/trace_event/trace_event.h"
 #include "content/renderer/media/webrtc/track_observer.h"
 #include "media/base/bind_to_current_loop.h"
+#include "media/base/timestamp_constants.h"
 #include "media/base/video_frame.h"
 #include "media/base/video_util.h"
 #include "third_party/libjingle/source/talk/media/base/videoframe.h"
 #include "third_party/webrtc/system_wrappers/interface/tick_util.h"
 
 namespace content {
 
 // Internal class used for receiving frames from the webrtc track on a
 // libjingle thread and forward it to the IO-thread.
 class MediaStreamRemoteVideoSource::RemoteVideoSourceDelegate
@@ skipping 18 matching lines @@
 
  private:
   // Bound to the render thread.
   base::ThreadChecker thread_checker_;
 
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   // |frame_callback_| is accessed on the IO thread.
   VideoCaptureDeliverFrameCB frame_callback_;
 
+  // Timestamp of the first received frame.
+  base::TimeDelta start_timestamp_;
   // WebRTC Chromium timestamp diff
-  int64_t time_diff_us_;
+  const base::TimeDelta time_diff_;
 };
 
 MediaStreamRemoteVideoSource::RemoteVideoSourceDelegate::
     RemoteVideoSourceDelegate(
         scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
         const VideoCaptureDeliverFrameCB& new_frame_callback)
-    : io_task_runner_(io_task_runner), frame_callback_(new_frame_callback) {
-  // TODO(qiangchen): There can be two differences between clocks: 1)
-  // the offset, 2) the rate (i.e., one clock runs faster than the other).
-  // See http://crbug/516700
-  time_diff_us_ =
-      (base::TimeTicks::Now() - base::TimeTicks()).InMicroseconds() -
-      webrtc::TickTime::MicrosecondTimestamp();
-}
+    : io_task_runner_(io_task_runner),
+      frame_callback_(new_frame_callback),
+      start_timestamp_(media::kNoTimestamp()),

[tommi (sloooow) - chröme, 2015/09/25 07:53:50]

Is kNoTimestamp a function? 

[magjed_chromium, 2015/09/25 08:21:35]

Yes, it looks like this:
MEDIA_EXPORT inline base::TimeDelta kNoTimestamp() {
  return base::TimeDelta::FromMicroseconds(kint64min);
}
I reused the code where we set the cricket::CapturedFrame.elapsed_time in the
first place:
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/m...
That logic can be removed when this and the WebRTC CL lands btw.

I can add a bool flag |has_received_frame_| instead if you want. It is a bit
scary to reserve one of the timestamps with a special meaning. In theory,
kNoTimestamp() can be generated by a camera.

+      // TODO(qiangchen): There can be two differences between clocks: 1)
+      // the offset, 2) the rate (i.e., one clock runs faster than the other).
+      // See http://crbug/516700
+      time_diff_(base::TimeTicks::Now() - base::TimeTicks() -
+                 base::TimeDelta::FromMicroseconds(
+                     webrtc::TickTime::MicrosecondTimestamp())) {}
 
 MediaStreamRemoteVideoSource::
 RemoteVideoSourceDelegate::~RemoteVideoSourceDelegate() {
 }
 
 void MediaStreamRemoteVideoSource::RemoteVideoSourceDelegate::RenderFrame(
     const cricket::VideoFrame* incoming_frame) {
-  base::TimeTicks render_time =
-      base::TimeTicks() +
-      base::TimeDelta::FromMicroseconds(incoming_frame->GetTimeStamp() / 1000 +
-                                        time_diff_us_);
+  const base::TimeDelta incoming_timestamp = base::TimeDelta::FromMicroseconds(
+      incoming_frame->GetTimeStamp() / rtc::kNumNanosecsPerMicrosec);
+  const base::TimeTicks render_time =
+      base::TimeTicks() + incoming_timestamp + time_diff_;
 
   TRACE_EVENT1("webrtc", "RemoteVideoSourceDelegate::RenderFrame",
                "Ideal Render Instant", render_time.ToInternalValue());
 
-  base::TimeDelta timestamp = base::TimeDelta::FromMicroseconds(
-      incoming_frame->GetElapsedTime() / rtc::kNumNanosecsPerMicrosec);
+  if (start_timestamp_ == media::kNoTimestamp())
+    start_timestamp_ = incoming_timestamp;
+  const base::TimeDelta elapsed_timestamp =
+      incoming_timestamp - start_timestamp_;
 
   scoped_refptr<media::VideoFrame> video_frame;
   if (incoming_frame->GetNativeHandle() != NULL) {
     video_frame =
         static_cast<media::VideoFrame*>(incoming_frame->GetNativeHandle());
-    video_frame->set_timestamp(timestamp);
+    video_frame->set_timestamp(elapsed_timestamp);
   } else {
     const cricket::VideoFrame* frame =
         incoming_frame->GetCopyWithRotationApplied();
 
     gfx::Size size(frame->GetWidth(), frame->GetHeight());
 
     // Non-square pixels are unsupported.
     DCHECK_EQ(frame->GetPixelWidth(), 1u);
     DCHECK_EQ(frame->GetPixelHeight(), 1u);
 
     // Make a shallow copy. Both |frame| and |video_frame| will share a single
     // reference counted frame buffer. Const cast and hope no one will overwrite
     // the data.
     // TODO(magjed): Update media::VideoFrame to support const data so we don't
     // need to const cast here.
     video_frame = media::VideoFrame::WrapExternalYuvData(
         media::PIXEL_FORMAT_YV12, size, gfx::Rect(size), size,
         frame->GetYPitch(), frame->GetUPitch(), frame->GetVPitch(),
         const_cast<uint8_t*>(frame->GetYPlane()),
         const_cast<uint8_t*>(frame->GetUPlane()),
-        const_cast<uint8_t*>(frame->GetVPlane()), timestamp);
+        const_cast<uint8_t*>(frame->GetVPlane()), elapsed_timestamp);
     video_frame->AddDestructionObserver(
         base::Bind(&base::DeletePointer<cricket::VideoFrame>, frame->Copy()));
   }
 
   video_frame->metadata()->SetTimeTicks(
       media::VideoFrameMetadata::REFERENCE_TIME, render_time);
 
   io_task_runner_->PostTask(
       FROM_HERE, base::Bind(&RemoteVideoSourceDelegate::DoRenderFrameOnIOThread,
                             this, video_frame));
@@ skipping 73 matching lines @@
     case webrtc::MediaStreamTrackInterface::kEnded:
       SetReadyState(blink::WebMediaStreamSource::ReadyStateEnded);
       break;
     default:
       NOTREACHED();
       break;
   }
 }
 
 }  // namespace content