Fix and improve FlexFEC configuration for RTP/RTCP.

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 1206 matching lines @@
   // "recv_params" to "receiver_params", we should get this out of
   // receiver_params_.
   config->rtp.rtcp_mode = send_params_.rtcp.reduced_size
                               ? webrtc::RtcpMode::kReducedSize
                               : webrtc::RtcpMode::kCompound;
 
   config->rtp.remb = send_codec_ ? HasRemb(send_codec_->codec) : false;
   config->rtp.transport_cc =
       send_codec_ ? HasTransportCc(send_codec_->codec) : false;
 
+  sp.GetFidSsrc(ssrc, &config->rtp.rtx_ssrc);
+
+  config->rtp.extensions = recv_rtp_extensions_;
+
   // TODO(brandtr): Generalize when we add support for multistream protection.
   if (sp.GetFecFrSsrc(ssrc, &flexfec_config->remote_ssrc)) {
     flexfec_config->protected_media_ssrcs = {ssrc};
     flexfec_config->local_ssrc = config->rtp.local_ssrc;
     flexfec_config->rtcp_mode = config->rtp.rtcp_mode;
+    // TODO(brandtr): We should be spec-compliant and set |transport_cc| here
+    // based on the rtcp-fb for the FlexFEC codec, not the media codec.
     flexfec_config->transport_cc = config->rtp.transport_cc;
     flexfec_config->rtp_header_extensions = config->rtp.extensions;

[brandtr, 2017/02/01 10:11:40]

Note how this assignment is affected by the move of line 1238.

This incorrect order was due to the the interaction of the two CLs in the
description.

   }
-
-  sp.GetFidSsrc(ssrc, &config->rtp.rtx_ssrc);
-
-  config->rtp.extensions = recv_rtp_extensions_;
 }
 
 bool WebRtcVideoChannel2::RemoveRecvStream(uint32_t ssrc) {
   LOG(LS_INFO) << "RemoveRecvStream: " << ssrc;
   if (ssrc == 0) {
     LOG(LS_ERROR) << "RemoveRecvStream with 0 ssrc is not supported.";
     return false;
   }
 
   rtc::CritScope stream_lock(&stream_crit_);
@@ skipping 994 matching lines @@
         << "Ignoring call to SetFeedbackParameters because parameters are "
            "unchanged; nack="
         << nack_enabled << ", remb=" << remb_enabled
         << ", transport_cc=" << transport_cc_enabled;
     return;
   }
   config_.rtp.remb = remb_enabled;
   config_.rtp.nack.rtp_history_ms = nack_history_ms;
   config_.rtp.transport_cc = transport_cc_enabled;
   config_.rtp.rtcp_mode = rtcp_mode;
-  flexfec_config_.rtcp_mode = rtcp_mode;
+  // TODO(brandtr): We should be spec-compliant and set |transport_cc| here
+  // based on the rtcp-fb for the FlexFEC codec, not the media codec.
+  flexfec_config_.transport_cc = config_.rtp.transport_cc;
+  flexfec_config_.rtcp_mode = config_.rtp.rtcp_mode;
   LOG(LS_INFO)
       << "RecreateWebRtcStream (recv) because of SetFeedbackParameters; nack="
       << nack_enabled << ", remb=" << remb_enabled
       << ", transport_cc=" << transport_cc_enabled;
   RecreateWebRtcStream();
 }
 
 void WebRtcVideoChannel2::WebRtcVideoReceiveStream::SetRecvParameters(
     const ChangedRecvParameters& params) {
   bool needs_recreation = false;
   std::vector<AllocatedDecoder> old_decoders;
   if (params.codec_settings) {
     ConfigureCodecs(*params.codec_settings, &old_decoders);
     needs_recreation = true;
   }
   if (params.rtp_header_extensions) {
     config_.rtp.extensions = *params.rtp_header_extensions;
+    flexfec_config_.rtp_header_extensions = *params.rtp_header_extensions;
     needs_recreation = true;
   }
   if (needs_recreation) {
     LOG(LS_INFO) << "RecreateWebRtcStream (recv) because of SetRecvParameters";
     RecreateWebRtcStream();
     ClearDecoders(&old_decoders);
   }
 }
 
 void WebRtcVideoChannel2::WebRtcVideoReceiveStream::RecreateWebRtcStream() {
@@ skipping 236 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