diff options
Diffstat (limited to 'libavformat')
| -rw-r--r-- | libavformat/sdp.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/libavformat/sdp.c b/libavformat/sdp.c index a926cf89f2..d7429523e8 100644 --- a/libavformat/sdp.c +++ b/libavformat/sdp.c @@ -597,8 +597,18 @@ static char *sdp_write_media_attributes(char *buff, int size, AVCodecContext *c, } break; case AV_CODEC_ID_OPUS: - av_strlcatf(buff, size, "a=rtpmap:%d opus/48000\r\n", + /* The opus RTP draft says that all opus streams MUST be declared + as stereo, to avoid negotiation failures. The actual number of + channels can change on a packet-by-packet basis. The number of + channels a receiver prefers to receive or a sender plans to send + can be declared via fmtp parameters (both default to mono), but + receivers MUST be able to receive and process stereo packets. */ + av_strlcatf(buff, size, "a=rtpmap:%d opus/48000/2\r\n", payload_type); + if (c->channels == 2) { + av_strlcatf(buff, size, "a=fmtp:%d sprop-stereo:1\r\n", + payload_type); + } break; default: /* Nothing special to do here... */ |