DCHECK that no RTPPayloadRegistry instance is used for both audio and video

webrtc/modules/rtp_rtcp/source/rtp_payload_registry.cc

 /*
  *  Copyright (c) 2013 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 103 matching lines @@
     : incoming_payload_type_(-1),
       last_received_payload_type_(-1),
       last_received_media_payload_type_(-1),
       rtx_(false),
       ssrc_rtx_(0) {}
 
 RTPPayloadRegistry::~RTPPayloadRegistry() = default;
 
 int32_t RTPPayloadRegistry::RegisterReceivePayload(const CodecInst& audio_codec,
                                                    bool* created_new_payload) {
+#if RTC_DCHECK_IS_ON
+  RTC_DCHECK(!used_for_video_);
+  used_for_audio_ = true;
+#endif
+
   *created_new_payload = false;
   if (!IsPayloadTypeValid(audio_codec.pltype))
     return -1;
 
   rtc::CritScope cs(&crit_sect_);

[the sun, 2017/03/22 14:28:01]

My only concern would be whether this class is raceful, and you need to do the
above check while holding the lock?

[kwiberg-webrtc, 2017/03/22 17:46:42]

Good point. I'll do that.

 
   auto it = payload_type_map_.find(audio_codec.pltype);
   if (it != payload_type_map_.end()) {
     // We already use this payload type. Check if it's the same as we already
     // have. If same, ignore sending an error.
     if (PayloadIsCompatible(it->second, audio_codec)) {
       it->second.typeSpecific.Audio.rate = 0;
       return 0;
     }
     LOG(LS_ERROR) << "Payload type already registered: " << audio_codec.pltype;
     return -1;
   }
 
   // Audio codecs must be unique.
   DeregisterAudioCodecOrRedTypeRegardlessOfPayloadType(audio_codec);
 
   payload_type_map_[audio_codec.pltype] = CreatePayloadType(audio_codec);
   *created_new_payload = true;
 
   // Successful set of payload type, clear the value of last received payload
   // type since it might mean something else.
   last_received_payload_type_ = -1;
   last_received_media_payload_type_ = -1;
   return 0;
 }
 
 int32_t RTPPayloadRegistry::RegisterReceivePayload(
     const VideoCodec& video_codec) {
+#if RTC_DCHECK_IS_ON
+  RTC_DCHECK(!used_for_audio_);
+  used_for_video_ = true;
+#endif
+
   if (!IsPayloadTypeValid(video_codec.plType))
     return -1;
 
   rtc::CritScope cs(&crit_sect_);
 
   auto it = payload_type_map_.find(video_codec.plType);
   if (it != payload_type_map_.end()) {
     // We already use this payload type. Check if it's the same as we already
     // have. If same, ignore sending an error.
     if (PayloadIsCompatible(it->second, video_codec))
@@ skipping 219 matching lines @@
     const char* payload_name) const {
   rtc::CritScope cs(&crit_sect_);
   for (const auto& it : payload_type_map_) {
     if (_stricmp(it.second.name, payload_name) == 0)
       return it.first;
   }
   return -1;
 }
 
 }  // namespace webrtc