m=audio 9 RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:ufrag_voice
a=ice-pwd:pwd_voice
a=mid:audio_content_name
a=sendrecv
a=rtpmap:111 opus/48000/2
a=ssrc:1 cname:stream_1_cname
a=ssrc:1 msid:local_stream audio_track_id_1
a=ssrc:1 mslabel:local_stream
a=ssrc:1 label:audio_track_id_1