Negotiate H264 profiles in SDP

webrtc/common_video/h264/profile_level_id.cc

 /*
  *  Copyright (c) 2016 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 245 matching lines @@
   char str[7];
   snprintf(str, 7u, "%s%02x", profile_idc_iop_string, profile_level_id.level);
   return rtc::Optional<std::string>(str);
 }
 
 // Set level according to https://tools.ietf.org/html/rfc6184#section-8.2.2.
 void GenerateProfileLevelIdForAnswer(
     const CodecParameterMap& local_supported_params,
     const CodecParameterMap& remote_offered_params,
     CodecParameterMap* answer_params) {
+  // If both local and remote haven't set profile-level-id, they are both using
+  // the default profile. In this case, don't set profile-level-id in answer
+  // either.
+  if (!local_supported_params.count(kProfileLevelId) &&
+      !remote_offered_params.count(kProfileLevelId)) {
+    return;
+  }
+
   // Parse profile-level-ids.
   const rtc::Optional<ProfileLevelId> local_profile_level_id =
       ParseSdpProfileLevelId(local_supported_params);
   const rtc::Optional<ProfileLevelId> remote_profile_level_id =
       ParseSdpProfileLevelId(remote_offered_params);
   // The local and remote codec must have valid and equal H264 Profiles.
   RTC_DCHECK(local_profile_level_id);
   RTC_DCHECK(remote_profile_level_id);
   RTC_DCHECK_EQ(local_profile_level_id->profile,
                 remote_profile_level_id->profile);
@@ skipping 11 matching lines @@
   // than the level in the offer.
   const Level answer_level = level_asymmetry_allowed ? local_level : min_level;
 
   // Set the resulting profile-level-id in the answer parameters.
   (*answer_params)[kProfileLevelId] = *ProfileLevelIdToString(
       ProfileLevelId(local_profile_level_id->profile, answer_level));
 }
 
 }  // namespace H264
 }  // namespace webrtc