Rewrite CreateBlackFrame in webrtcvideoengine.

webrtc/media/engine/webrtcvideoengine2.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 1559 matching lines @@
 }
 
 WebRtcVideoChannel2::WebRtcVideoSendStream::~WebRtcVideoSendStream() {
   DisconnectSource();
   if (stream_ != NULL) {
     call_->DestroyVideoSendStream(stream_);
   }
   DestroyVideoEncoder(&allocated_encoder_);
 }
 
-static webrtc::VideoFrame CreateBlackFrame(int width,
-                                           int height,
-                                           int64_t render_time_ms_,
-                                           webrtc::VideoRotation rotation) {
-  webrtc::VideoFrame frame;
-  frame.CreateEmptyFrame(width, height, width, (width + 1) / 2,
-                         (width + 1) / 2);
-  memset(frame.video_frame_buffer()->MutableDataY(), 16,
-         frame.allocated_size(webrtc::kYPlane));
-  memset(frame.video_frame_buffer()->MutableDataU(), 128,
-         frame.allocated_size(webrtc::kUPlane));
-  memset(frame.video_frame_buffer()->MutableDataV(), 128,
-         frame.allocated_size(webrtc::kVPlane));
-  frame.set_rotation(rotation);
-  frame.set_render_time_ms(render_time_ms_);
-  return frame;
-}
-
 void WebRtcVideoChannel2::WebRtcVideoSendStream::OnFrame(
     const VideoFrame& frame) {
   TRACE_EVENT0("webrtc", "WebRtcVideoSendStream::OnFrame");
   webrtc::VideoFrame video_frame(frame.video_frame_buffer(), 0, 0,
                                  frame.rotation());
   rtc::CritScope cs(&lock_);
 
   if (video_frame.width() != last_frame_info_.width ||
       video_frame.height() != last_frame_info_.height ||
       video_frame.rotation() != last_frame_info_.rotation ||
@@ skipping 76 matching lines @@
       first_frame_timestamp_ms_ = rtc::Optional<int64_t>();
 
       if (source == nullptr && stream_ != nullptr) {
         LOG(LS_VERBOSE) << "Disabling capturer, sending black frame.";
         // Force this black frame not to be dropped due to timestamp order
         // check. As IncomingCapturedFrame will drop the frame if this frame's
         // timestamp is less than or equal to last frame's timestamp, it is
         // necessary to give this black frame a larger timestamp than the
         // previous one.
         last_frame_timestamp_ms_ += 1;
-        stream_->Input()->IncomingCapturedFrame(CreateBlackFrame(
-            last_frame_info_.width, last_frame_info_.height,
+        rtc::scoped_refptr<webrtc::I420Buffer> black_buffer(
+            webrtc::I420Buffer::Create(last_frame_info_.width,
+                                       last_frame_info_.height));
+        black_buffer->SetToBlack();
+
+        stream_->Input()->IncomingCapturedFrame(webrtc::VideoFrame(
+            black_buffer,  0 /* timestamp (90 kHz) */,

[pbos-webrtc, 2016/06/17 12:30:38]

Is this (zero-timestamp) the same as before? If so this might just be dropped,
I'm not sure if this code is alive.

[nisse-webrtc, 2016/06/17 13:26:12]

Before this cl, the 90 kHz timestamp on the frame was set to zero by the
webrtc::VideoFrame default initializer. 

And if you look at the OnFrame method, it also sets render_time_ms only. The
other two timestamps are populated by some pretty convoluted logic further down
the pipeline.

And I think the black-frame-on-source-change is tested by
WebRtcVideoChannel2BaseTest.AddRemoveCapturer, so it's somewhat alive.

             last_frame_timestamp_ms_, last_frame_info_.rotation));
       }
       source_ = source;
     }
   }
 
   // |source_->AddOrUpdateSink| may not be called while holding |lock_| since
   // that might cause a lock order inversion.
   if (source_changing && source_) {
     source_->AddOrUpdateSink(this, sink_wants_);
@@ skipping 921 matching lines @@
         rtx_mapping[video_codecs[i].codec.id] !=
             fec_settings.red_payload_type) {
       video_codecs[i].rtx_payload_type = rtx_mapping[video_codecs[i].codec.id];
     }
   }
 
   return video_codecs;
 }
 
 }  // namespace cricket