Add |protected_by_flexfec| flag to VideoReceiveStream::Config.

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 2277 matching lines @@
 
 void WebRtcVideoChannel2::WebRtcVideoReceiveStream::RecreateWebRtcStream() {
   if (stream_) {
     call_->DestroyVideoReceiveStream(stream_);
     stream_ = nullptr;
   }
   if (flexfec_stream_) {
     call_->DestroyFlexfecReceiveStream(flexfec_stream_);
     flexfec_stream_ = nullptr;
   }
-  if (IsFlexfecFieldTrialEnabled() && flexfec_config_.IsCompleteAndEnabled()) {
+
+  const bool use_flexfec =
+      IsFlexfecFieldTrialEnabled() && flexfec_config_.IsCompleteAndEnabled();
+  // TODO(nisse): There are way too many copies here. And why isn't
+  // the argument to CreateVideoReceiveStream a const ref?

[brandtr, 2017/02/23 11:58:32]

Agree that this should be cleaned up at some point. Right now, its a mixture of
copies and moves in the code that has to do with the VideoReceiveStream::Config.

[nisse-webrtc, 2017/02/23 13:01:22]

I noticed a std::move(configuration) in Call::CreateVideoReceiveStream, 
but it's not clear to me if it makes any difference.

Is there any easy way to eliminate at least the second Copy call here?

[brandtr, 2017/02/23 15:28:35]

I guess that std::move saves a copy at that call site.

I'm not sure if removing the copy here would change the logic overall in any
way. It might be good to be careful, it's my experience that it is fairly easy
to introduce bugs -- that are not found by tests -- in the configuration at this
layer.

+  webrtc::VideoReceiveStream::Config config = config_.Copy();
+  config.rtp.protected_by_flexfec = use_flexfec;
+  stream_ = call_->CreateVideoReceiveStream(config.Copy());
+  stream_->Start();
+
+  if (use_flexfec) {
     flexfec_stream_ = call_->CreateFlexfecReceiveStream(flexfec_config_);
     flexfec_stream_->Start();
   }
-  stream_ = call_->CreateVideoReceiveStream(config_.Copy());
-  stream_->Start();
 }
 
 void WebRtcVideoChannel2::WebRtcVideoReceiveStream::ClearDecoders(
     std::vector<AllocatedDecoder>* allocated_decoders) {
   for (size_t i = 0; i < allocated_decoders->size(); ++i) {
     if ((*allocated_decoders)[i].external) {
       external_decoder_factory_->DestroyVideoDecoder(
           (*allocated_decoders)[i].external_decoder);
     }
     delete (*allocated_decoders)[i].decoder;
@@ skipping 213 matching lines @@
         rtx_mapping[video_codecs[i].codec.id] !=
             ulpfec_config.red_payload_type) {
       video_codecs[i].rtx_payload_type = rtx_mapping[video_codecs[i].codec.id];
     }
   }
 
   return video_codecs;
 }
 
 }  // namespace cricket