RTC Video Encoder: implement timestamp fallback

content/renderer/media/rtc_video_encoder.cc

 // Copyright 2013 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/rtc_video_encoder.h"
 
 #include <string.h>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 455 matching lines @@
     return;
   }
   base::SharedMemory* output_buffer = output_buffers_[bitstream_buffer_id];
   if (payload_size > output_buffer->mapped_size()) {
     LogAndNotifyError(FROM_HERE, "invalid payload_size",
                       media::VideoEncodeAccelerator::kPlatformFailureError);
     return;
   }
   output_buffers_free_count_--;
 
-  // Derive the capture time (in ms) and RTP timestamp (in 90KHz ticks).
-  // This is based on how input timestamps are calculated in
-  // webrtc/video/video_capture_input.cc.
-  const uint32_t rtp_timestamp =
-      static_cast<uint32_t>(timestamp.InMilliseconds()) * 90;
+  uint32_t capture_time_ms = 0;
+  //if (timestamp.is_zero()) {
+    // Some platform does not pass captured timestamp through. Use the current
+    // time instead.
+    capture_time_ms = rtc::TimeMicros() / 1000;
+  //} else {
+  //  capture_time_ms = static_cast<uint32_t>(timestamp.InMilliseconds());
+  //}
 
   webrtc::EncodedImage image(
       reinterpret_cast<uint8_t*>(output_buffer->memory()), payload_size,
       output_buffer->mapped_size());
   image._encodedWidth = input_visible_size_.width();
   image._encodedHeight = input_visible_size_.height();
-  image._timeStamp = rtp_timestamp;
-  image.capture_time_ms_ = timestamp.InMilliseconds();
+  // This is based on how input timestamps are calculated in
+  // webrtc/video/video_capture_input.cc.
+  image._timeStamp = capture_time_ms * 90;
+  image.capture_time_ms_ = capture_time_ms;
   image._frameType =
       (key_frame ? webrtc::kVideoFrameKey : webrtc::kVideoFrameDelta);
   image._completeFrame = true;
 
   ReturnEncodedImage(image, bitstream_buffer_id, picture_id_);
   // Picture ID must wrap after reaching the maximum.
   picture_id_ = (picture_id_ + 1) & 0x7FFF;
 }
 
 void RTCVideoEncoder::Impl::NotifyError(
@@ skipping 61 matching lines @@
     requires_copy = true;
   }
 
   if (requires_copy) {
     base::SharedMemory* input_buffer = input_buffers_[index];
     frame = media::VideoFrame::WrapExternalSharedMemory(
         media::PIXEL_FORMAT_I420, input_frame_coded_size_,
         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::FromMilliseconds(next_frame->ntp_time_ms()));

[wuchengli, 2016/06/17 03:50:51]

maybe because this line should also be reverted?

     if (!frame.get()) {
       LogAndNotifyError(FROM_HERE, "failed to create frame",
                         media::VideoEncodeAccelerator::kPlatformFailureError);
       return;
     }
     // Do a strided copy of the input frame to match the input requirements for
     // the encoder.
     // TODO(sheu): support zero-copy from WebRTC.  http://crbug.com/269312
     if (libyuv::I420Copy(next_frame->video_frame_buffer()->DataY(),
                          next_frame->video_frame_buffer()->StrideY(),
@@ skipping 281 matching lines @@
   UMA_HISTOGRAM_BOOLEAN("Media.RTCVideoEncoderInitEncodeSuccess",
                         init_retval == WEBRTC_VIDEO_CODEC_OK);
   if (init_retval == WEBRTC_VIDEO_CODEC_OK) {
     UMA_HISTOGRAM_ENUMERATION("Media.RTCVideoEncoderProfile",
                               profile,
                               media::VIDEO_CODEC_PROFILE_MAX + 1);
   }
 }
 
 }  // namespace content