Filter overlapping RTP header extensions.

talk/media/webrtc/webrtcmediaengine.cc

 /*
  * libjingle
  * Copyright 2014 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 50 matching lines @@
 
 // Used by PeerConnectionFactory to create a media engine passed into
 // ChannelManager.
 MediaEngineInterface* WebRtcMediaEngineFactory::Create(
     webrtc::AudioDeviceModule* adm,
     WebRtcVideoEncoderFactory* encoder_factory,
     WebRtcVideoDecoderFactory* decoder_factory) {
   return CreateWebRtcMediaEngine(adm, encoder_factory, decoder_factory);
 }
 
+static const std::map<std::string, int> CreateBweExtensionPriorities() {
+  std::map<std::string, int> extension_prios;
+  extension_prios[kRtpTransportSequenceNumberHeaderExtension] = 0;
+  extension_prios[kRtpAbsoluteSenderTimeHeaderExtension] = 1;
+  extension_prios[kRtpTimestampOffsetHeaderExtension] = 2;
+  return extension_prios;
+}
+const std::map<std::string, int> kBweExtensionPriorities =
+    CreateBweExtensionPriorities();

[pbos-webrtc, 2015/10/29 14:16:22]

Static initializer, not permitted. Can you make this a POD struct {const char*,
int} instead? Scanning through a map with 3 elements shouldn't be more effective
either way.

[stefan-webrtc, 2015/10/29 14:51:11]

Done.

+
+std::vector<RtpHeaderExtension> FilterOverlappingRtpExtensions(
+    const std::vector<RtpHeaderExtension>& extensions,
+    const std::map<std::string, int>& extension_prios) {
+  if (extensions.empty())
+    return std::vector<RtpHeaderExtension>();
+  std::vector<RtpHeaderExtension> filtered;
+  std::map<int, const RtpHeaderExtension*> sorted;
+  for (auto& extension : extensions) {
+    auto it = extension_prios.find(extension.uri);
+    if (it == extension_prios.end()) {
+      filtered.push_back(extension);
+      continue;
+    } else {
+      sorted[it->second] = &extension;
+    }
+  }
+  if (!sorted.empty())
+    filtered.push_back(*sorted.begin()->second);
+  return filtered;
+}
+
 }  // namespace cricket