RTC Video Encoder: Use capturer timestamp

content/renderer/media/rtc_video_encoder.cc

Index: content/renderer/media/rtc_video_encoder.cc
diff --git a/content/renderer/media/rtc_video_encoder.cc b/content/renderer/media/rtc_video_encoder.cc
index 103e0c102b07a0413ffd35ffe174ec67e688bc1d..a8b1d4fb5d80a5f241949d9178d3b9301255d7f0 100644
--- a/content/renderer/media/rtc_video_encoder.cc
+++ b/content/renderer/media/rtc_video_encoder.cc
@@ -149,7 +149,8 @@ class RTCVideoEncoder::Impl
                                size_t output_buffer_size) override;
   void BitstreamBufferReady(int32_t bitstream_buffer_id,
                             size_t payload_size,
-                            bool key_frame) override;
+                            bool key_frame,
+                            base::TimeDelta timestamp) override;
   void NotifyError(media::VideoEncodeAccelerator::Error error) override;
 
  private:
@@ -449,8 +450,9 @@ void RTCVideoEncoder::Impl::RequireBitstreamBuffers(
 }
 
 void RTCVideoEncoder::Impl::BitstreamBufferReady(int32_t bitstream_buffer_id,
-                                                 size_t payload_size,
-                                                 bool key_frame) {
+    size_t payload_size,
+    bool key_frame,
+    base::TimeDelta timestamp) {
   DVLOG(3) << "Impl::BitstreamBufferReady(): "
               "bitstream_buffer_id=" << bitstream_buffer_id
            << ", payload_size=" << payload_size
@@ -471,9 +473,7 @@ void RTCVideoEncoder::Impl::BitstreamBufferReady(int32_t bitstream_buffer_id,
   }
   output_buffers_free_count_--;
 
-  // Use webrtc timestamps to ensure correct RTP sender behavior.
-  // TODO(hshi): obtain timestamp from the capturer, see crbug.com/350106.
-  const int64_t capture_time_us = rtc::TimeMicros();
+  const int64_t capture_time_us = timestamp.InMicroseconds();

[Pawel Osciak, 2016/05/23 07:15:52]

Please remove this line and at l.489:

image.capture_time_ms_ = timestamp.InMilliseconds();

[shenghao, 2016/05/24 10:50:19]

Done.

 
   // Derive the capture time (in ms) and RTP timestamp (in 90KHz ticks).
   const int64_t capture_time_ms = capture_time_us / 1000;

[Pawel Osciak, 2016/05/23 07:15:52]

This could also be removed and l.480 modified accordingly.

[shenghao, 2016/05/24 10:50:19]

Done.

@@ -568,7 +568,7 @@ void RTCVideoEncoder::Impl::EncodeOneFrame() {
         gfx::Rect(input_visible_size_), input_visible_size_,
         reinterpret_cast<uint8_t*>(input_buffer->memory()),
         input_buffer->mapped_size(), input_buffer->handle(), 0,
-        base::TimeDelta());
+        base::TimeDelta::FromMilliseconds(next_frame->ntp_time_ms()));

[pbos, 2016/05/20 12:15:51]

This needs to copy over next_frame->timestamp(), not the NTP time. We need the
RTP timestamps to match.

Be careful about rounding errors as well, we use this timestamp to match
incoming frames with outgoing frames.

[shenghao, 2016/05/24 10:50:19]

Talked offline. We agreed to use ntp_time_ms()

     if (!frame.get()) {
       LogAndNotifyError(FROM_HERE, "failed to create frame",
                         media::VideoEncodeAccelerator::kPlatformFailureError);