commit 116ada2ed2aa98de38132699153eca6d646561eb
author brandtr <brandtr@webrtc.org> Tue Feb 28 23:43:10 2017
committer Commit bot <commit-bot@chromium.org> Tue Feb 28 23:43:10 2017
tree 21c8377b498fa4bd6e3e8bdb246f660a5fa1be20
parent b880884d6ee31236d3e6a96fbce4180e19e7eb6a

Split FlexFEC field trial in two.

- The "flexfec-03" codec is advertised in the SDP whenever the
  "WebRTC-FlexFEC-03-Advertised" field trial is enabled.
- Sending FlexFEC packets is enabled whenever the "flexfec-03" codec is
  negotiated, and the "WebRTC-FlexFEC-03" field trial is enabled.

After this CL, the number of calls to
WebRtcVideoChannel2::WebRtcVideoSendStream::SetCodec during renegotiation
will be reduced for cases when only one endpoint has the "WebRTC-FlexFEC-03"
field trial enabled.

BUG=webrtc:5654

Review-Url: https://codereview.webrtc.org/2716733005
Cr-Original-Commit-Position: refs/heads/master@{#16925}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 340e3fd59f2af4b13e5ffb8430cf87e15f334066

media/engine/webrtcvideoengine2.cc

diff --git a/media/engine/webrtcvideoengine2.cc b/media/engine/webrtcvideoengine2.cc
index 9f37f33..8b4c5df 100644
--- a/media/engine/webrtcvideoengine2.cc
+++ b/media/engine/webrtcvideoengine2.cc
@@ -41,16 +41,11 @@
 namespace cricket {
 namespace {
 
-// Three things happen when the FlexFEC field trial is enabled:
-// 1) FlexFEC is exposed in the default codec list, eventually showing up
-//    in the default SDP. (See InternalEncoderFactory ctor.)
-// 2) FlexFEC send parameters are set in the VideoSendStream config.
-// 3) FlexFEC receive parameters are set in the FlexfecReceiveStream config,
-//    and the corresponding object is instantiated.
-const char kFlexfecFieldTrialName[] = "WebRTC-FlexFEC-03";
-
+// If this field trial is enabled, we will enable sending FlexFEC and disable
+// sending ULPFEC whenever the former has been negotiated. Receiving FlexFEC
+// is enabled whenever FlexFEC has been negotiated.
 bool IsFlexfecFieldTrialEnabled() {
-  return webrtc::field_trial::IsEnabled(kFlexfecFieldTrialName);
+  return webrtc::field_trial::FindFullName("WebRTC-FlexFEC-03") == "Enabled";
 }
 
 // Wrap cricket::WebRtcVideoEncoderFactory as a webrtc::VideoEncoderFactory.
@@ -1556,7 +1551,7 @@
   sp.GetFidSsrcs(parameters_.config.rtp.ssrcs,
                  &parameters_.config.rtp.rtx.ssrcs);
 
-  // FlexFEC.
+  // FlexFEC SSRCs.
   // TODO(brandtr): This code needs to be generalized when we add support for
   // multistream protection.
   if (IsFlexfecFieldTrialEnabled()) {
@@ -1731,8 +1726,10 @@
     parameters_.config.encoder_settings.internal_source = false;
   }
   parameters_.config.rtp.ulpfec = codec_settings.ulpfec;
-  parameters_.config.rtp.flexfec.payload_type =
-      codec_settings.flexfec_payload_type;
+  if (IsFlexfecFieldTrialEnabled()) {
+    parameters_.config.rtp.flexfec.payload_type =
+        codec_settings.flexfec_payload_type;
+  }
 
   // Set RTX payload type if RTX is enabled.
   if (!parameters_.config.rtp.rtx.ssrcs.empty()) {
@@ -2313,7 +2310,7 @@
     call_->DestroyFlexfecReceiveStream(flexfec_stream_);
     flexfec_stream_ = nullptr;
   }
-  if (IsFlexfecFieldTrialEnabled() && flexfec_config_.IsCompleteAndEnabled()) {
+  if (flexfec_config_.IsCompleteAndEnabled()) {
     flexfec_stream_ = call_->CreateFlexfecReceiveStream(flexfec_config_);
     flexfec_stream_->Start();
   }