Add content type extension to capabilities

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 31 matching lines @@
 
 namespace cricket {
 namespace {
 // 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::FindFullName("WebRTC-FlexFEC-03") == "Enabled";
 }
 
+// If this field trial is enabled, we will report VideoContentType RTP extension

[brandtr, 2017/04/13 10:00:25]

But the effect of adding this extension to the capabilities means that it will
show up in the default offer SDP, and therefore by default will be sent, if
negotiated?

[ilnik, 2017/04/13 10:12:28]

Yes. I have updated the comment to be more detailed.

+// in capabilities.
+bool IsVideoContentTypeExtensionFieldTrialEnabled() {
+  return webrtc::field_trial::IsEnabled("WebRTC-VideoContentTypeExtension");
+}
+
 // Wrap cricket::WebRtcVideoEncoderFactory as a webrtc::VideoEncoderFactory.
 class EncoderFactoryAdapter : public webrtc::VideoEncoderFactory {
  public:
   // EncoderFactoryAdapter doesn't take ownership of |factory|, which is owned
   // by e.g. PeerConnectionFactory.
   explicit EncoderFactoryAdapter(cricket::WebRtcVideoEncoderFactory* factory)
       : factory_(factory) {}
   virtual ~EncoderFactoryAdapter() {}
 
   // Implement webrtc::VideoEncoderFactory.
@@ skipping 434 matching lines @@
                            webrtc::RtpExtension::kAbsSendTimeDefaultId));
   capabilities.header_extensions.push_back(
       webrtc::RtpExtension(webrtc::RtpExtension::kVideoRotationUri,
                            webrtc::RtpExtension::kVideoRotationDefaultId));
   capabilities.header_extensions.push_back(webrtc::RtpExtension(
       webrtc::RtpExtension::kTransportSequenceNumberUri,
       webrtc::RtpExtension::kTransportSequenceNumberDefaultId));
   capabilities.header_extensions.push_back(
       webrtc::RtpExtension(webrtc::RtpExtension::kPlayoutDelayUri,
                            webrtc::RtpExtension::kPlayoutDelayDefaultId));
+  if (IsVideoContentTypeExtensionFieldTrialEnabled()) {
+    capabilities.header_extensions.push_back(
+        webrtc::RtpExtension(webrtc::RtpExtension::kVideoContentTypeUri,
+                             webrtc::RtpExtension::kVideoContentTypeDefaultId));
+  }
   return capabilities;
 }
 
 void WebRtcVideoEngine2::SetExternalDecoderFactory(
     WebRtcVideoDecoderFactory* decoder_factory) {
   RTC_DCHECK(!initialized_);
   external_decoder_factory_ = decoder_factory;
 }
 
 void WebRtcVideoEngine2::SetExternalEncoderFactory(
@@ skipping 2045 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