[Remoting Host] Supporting WebRTC VP9 streaming

remoting/protocol/webrtc_video_stream.cc

Index: remoting/protocol/webrtc_video_stream.cc
diff --git a/remoting/protocol/webrtc_video_stream.cc b/remoting/protocol/webrtc_video_stream.cc
index 8c2478bf7b1fd0ce525d646143071d111bd8f423..96abf30bd4b0e9e00ef31faef82e02ff5228a8dc 100644
--- a/remoting/protocol/webrtc_video_stream.cc
+++ b/remoting/protocol/webrtc_video_stream.cc
@@ -4,6 +4,8 @@
 
 #include "remoting/protocol/webrtc_video_stream.h"
 
+#include <utility>
+
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
 #include "base/task_runner_util.h"
@@ -74,8 +76,11 @@ void WebrtcVideoStream::Start(
   encode_task_runner_ = std::move(encode_task_runner);
   capturer_ = std::move(desktop_capturer);
   webrtc_transport_ = webrtc_transport;
-  // TODO(isheriff): make this codec independent
-  encoder_ = WebrtcVideoEncoderVpx::CreateForVP8();
+
+  webrtc_transport_->video_encoder_factory()->SetEncoderCreatedCallback(

[Sergey Ulanov, 2017/03/31 19:23:11]

Maybe call it "EncoderSelectedCallback"? That would help to avoid confusion as
the encoder is actually created by the handler of this calblack.

[Yuwei, 2017/04/03 22:29:10]

Done.

+      base::Bind(&WebrtcVideoStream::OnEncoderCreated,
+                 weak_factory_.GetWeakPtr()));
+
   capturer_->Start(this);
 
   // Set video stream constraints.
@@ -162,6 +167,11 @@ void WebrtcVideoStream::OnCaptureResult(
     }
   }
 
+  if (!encoder_) {
+    LOG(WARNING) << "Encoder has not been created yet.";

[Yuwei, 2017/03/29 01:08:33]

I'm not sure whether this is very safe but IIUC the scheduler will always
capture new frames as long as the last frame has captured and it's the
|encoder_| itself deciding how to do incremental updates.

Let me know if I got anything wrong O_o

[Sergey Ulanov, 2017/03/31 19:23:11]

I think we need to fix this in WebrtcFrameSchedulerSimple. It shouldn't request
a frame until OnKeyFrameRequested() is called for the first time (by
WebrtcDummyVideoEncoder::Encode()). The first key frame request indicates that
the capturer has been created successfully.
WebrtcFrameSchedulerSimple::ScheduleNextFrame() should only schedule a frame if
a key frame request has been received.

[Yuwei, 2017/04/03 22:29:10]

Done.

+    return;
+  }
+
   base::PostTaskAndReplyWithResult(
       encode_task_runner_.get(), FROM_HERE,
       base::Bind(&WebrtcVideoStream::EncodeFrame, encoder_.get(),
@@ -254,5 +264,16 @@ void WebrtcVideoStream::OnFrameEncoded(EncodedFrameWithTimestamps frame) {
   }
 }
 
+void WebrtcVideoStream::OnEncoderCreated(webrtc::VideoCodecType codec_type) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (codec_type == webrtc::kVideoCodecVP8) {
+    encoder_ = WebrtcVideoEncoderVpx::CreateForVP8();
+  } else if (codec_type == webrtc::kVideoCodecVP9) {
+    encoder_ = WebrtcVideoEncoderVpx::CreateForVP9();
+  } else {
+    LOG(FATAL) << "Unknown codec type: " << codec_type;
+  }
+}
+
 }  // namespace protocol
 }  // namespace remoting