Streaming audio only WebRTC not working

[AronBuzogany]

I have the following code to stream audio to my media server:

  const start = async (videoId: Number) => {
    try {
      const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
      navigator.mediaDevices.getUserMedia({ audio: true })
        .then(stream => {
          stream.getTracks().forEach(track => console.log(track.readyState, track.kind));
        })
        .catch(error => console.error("Microphone access error:", error));


      const peerConnection = new RTCPeerConnection({
        bundlePolicy: "max-bundle",
      });

      stream.getTracks().forEach((track) => peerConnection.addTrack(track, stream));

      const offer = await peerConnection.createOffer();
      if (!offer.sdp) {
        throw new Error("Creation of offer sdp failed.");
      }

      await peerConnection.setLocalDescription(offer);

      const response = await fetch(`http://${MEDIA_SERVER_URL}:1985/rtc/v1/publish/`, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          sdp: offer.sdp,
          streamurl: `webrtc://${MEDIA_SERVER_URL}/audio/${videoId}`,
          codec: "opus",
        }),
      });

      
      const result: { sdp?: string } = await response.json();
      if (!result.sdp) {
        throw new Error("Invalid SDP response from SRS");
      }


      await peerConnection.setRemoteDescription(new RTCSessionDescription({ type: "answer", sdp: result.sdp }));

      peerConnectionRef.current = peerConnection;
      setIsStreaming(true);
    } catch (error) {
      console.error("Error starting stream:", error);
    }
  };

However I get the following when visiting /api/v1/streams/

{"id":"vid-qkw37tb","name":"130","vhost":"vid-5577384","app":"audio","tcUrl":"webrtc://IP/audio","url":"/audio/130","live_ms":1742905544805,"clients":1,"frames":0,"send_bytes":13628,"recv_bytes":561640,"kbps":{"recv_30s":42,"send_30s":0},"publish":{"active":true,"cid":"0oln5ag6"},"video":null,"audio":null}

video: null makes sense, but "audio": null doesn't.

What could the reason be behind this?

[2025-03-25 12:31:20.606][INFO][1][t36vf4i1] RTC publish webrtc://IP/audio/131, api=, tid=, clientip=192.168.113.3, app=audio, stream=131, offer=1295B, eip=, codec=
[2025-03-25 12:31:20.607][INFO][1][t36vf4i1] ignore attribute=, value=
[2025-03-25 12:31:20.607][INFO][1][t36vf4i1] new rtc source, stream_url=/audio/131
[2025-03-25 12:31:20.607][INFO][1][t36vf4i1] RTC publisher nack=1, nnc=1, pt-drop=0, twcc=0/-1
[2025-03-25 12:31:20.607][INFO][1][t36vf4i1] RTC: Init tracks {track: 76c4e0f5-1d6d-45f5-a542-42b0dc20853e, is_active: 0=>1}, ok
[2025-03-25 12:31:20.607][INFO][1][t36vf4i1] RTC: Use candidates IP protocol=udp
[2025-03-25 12:31:20.608][INFO][1][t36vf4i1] RTC init session, user=0wp60583:+eJD, url=/audio/131, encrypt=1/1, DTLS(role=passive, version=auto), timeout=30000ms, nack=1
[2025-03-25 12:31:20.608][INFO][1][t36vf4i1] RTC username=0wp60583:+eJD, offer=1295B, answer=745B
[2025-03-25 12:31:20.608][INFO][1][t36vf4i1] RTC remote offer: v=0\r\no=- 8855250097658786536 2 IN IP4 127.0.0.1\r\ns=-\r\nt=0 0\r\na=group:BUNDLE 0\r\na=extmap-allow-mixed\r\na=msid-semantic: WMS 910df5e3-6610-4bdd-a393-ca5109d4922c\r\nm=audio 9 UDP/TLS/RTP/SAVPF 111 63 9 0 8 13 110 126\r\nc=IN IP4 0.0.0.0\r\na=rtcp:9 IN IP4 0.0.0.0\r\na=ice-ufrag:+eJD\r\na=ice-pwd:cg2QlF8+uCdGI/sfF/u2q8qB\r\na=ice-options:trickle\r\na=fingerprint:sha-256 FE:27:71:35:F9:A8:67:ED:39:60:51:53:44:A3:55:BA:AC:04:90:81:20:32:52:FB:D0:23:07:F6:4F:E3:75:7B\r\na=setup:actpass\r\na=mid:0\r\na=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\r\na=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time\r\na=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\na=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid\r\na=sendrecv\r\na=msid:910df5e3-6610-4bdd-a393-ca5109d4922c 76c4e0f5-1d6d-45f5-a542-42b0dc20853e\r\na=rtcp-mux\r\na=rtcp-rsize\r\na=rtpmap:111 opus/48000/2\r\na=rtcp-fb:111 transport-cc\r\na=fmtp:111 minptime=10;useinbandfec=1\r\na=rtpmap:63 red/48000/2\r\na=fmtp:63 111/111\r\na=rtpmap:9 G722/8000\r\na=rtpmap:0 PCMU/8000\r\na=rtpmap:8 PCMA/8000\r\na=rtpmap:13 CN/8000\r\na=rtpmap:110 telephone-event/48000\r\na=rtpmap:126 telephone-event/8000\r\na=ssrc:3823440988 cname:YsmkNUIq6Krybk4s\r\na=ssrc:3823440988 msid:910df5e3-6610-4bdd-a393-ca5109d4922c 76c4e0f5-1d6d-45f5-a542-42b0dc20853e\r\n
[2025-03-25 12:31:20.608][INFO][1][t36vf4i1] RTC local answer: v=0\r\no=SRS/5.0.213(Bee) 140607657430848 2 IN IP4 0.0.0.0\r\ns=SRSPublishSession\r\nt=0 0\r\na=ice-lite\r\na=group:BUNDLE 0\r\na=msid-semantic: WMS audio/131\r\nm=audio 9 UDP/TLS/RTP/SAVPF 111\r\nc=IN IP4 0.0.0.0\r\na=ice-ufrag:0wp60583\r\na=ice-pwd:i54d0461cl15p9lm544o91i8509391h1\r\na=fingerprint:sha-256 F8:6D:F5:4C:10:13:D4:E0:48:AE:D1:94:6F:9F:AC:E6:4E:25:19:80:10:C4:DC:4F:74:1B:DE:C9:0B:89:24:4F\r\na=setup:passive\r\na=mid:0\r\na=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\na=recvonly\r\na=rtcp-mux\r\na=rtcp-rsize\r\na=rtpmap:111 opus/48000/2\r\na=rtcp-fb:111 transport-cc\r\na=fmtp:111 minptime=10;useinbandfec=1\r\na=candidate:0 1 udp 2130706431 IP 8000 typ host generation 0\r\n
[2025-03-25 12:31:20.658][INFO][1][t36vf4i1] TCP: before dispose resource(HttpConn)(0x7fe1c4f02860), conns=1, zombies=0, ign=0, inz=0, ind=0
[2025-03-25 12:31:20.658][WARN][1][t36vf4i1][104] client disconnect peer. ret=1007
[2025-03-25 12:31:20.658][INFO][1][83f0cdyi] TCP: clear zombies=1 resources, conns=1, removing=0, unsubs=0
[2025-03-25 12:31:20.658][INFO][1][t36vf4i1] TCP: disposing #0 resource(HttpConn)(0x7fe1c4f02860), conns=1, disposing=1, zombies=0
[2025-03-25 12:31:20.659][INFO][1][t36vf4i1] RTC: session address init 192.168.113.3:52113
[2025-03-25 12:31:20.659][INFO][1][t36vf4i1] RTC: session STUN done, waiting DTLS handshake.
[2025-03-25 12:31:20.664][INFO][1][t36vf4i1] DTLS: State Passive RECV, done=0, arq=0, r0=153, len=153, cnt=22, size=140, hs=1
[2025-03-25 12:31:20.664][INFO][1][t36vf4i1] DTLS: State Passive SEND, done=0, arq=0, r0=0, len=708, cnt=22, size=110, hs=2
[2025-03-25 12:31:20.667][INFO][1][t36vf4i1] DTLS: State Passive RECV, done=0, arq=0, r0=580, len=580, cnt=22, size=300, hs=11
[2025-03-25 12:31:20.668][INFO][1][t36vf4i1] DTLS: State Passive SEND, done=0, arq=0, r0=0, len=75, cnt=20, size=1, hs=1
[2025-03-25 12:31:20.668][INFO][1][t36vf4i1] RTC: DTLS handshake done.
[2025-03-25 12:31:20.668][INFO][1][t36vf4i1] RTC: session pub=1, sub=0, to=30000ms connection established
[2025-03-25 12:31:20.668][INFO][1][t36vf4i1] RTC: Publisher url=/audio/131 established
[2025-03-25 12:31:20.696][INFO][1][14205h1x] Process: cpu=1.00%,113MB, threads=2
[2025-03-25 12:31:20.837][INFO][1][t36vf4i1] RTC: session address change 192.168.113.3:52113 -> 192.168.113.3:55551, cached=0, nn_change=1/1, nn_address=1
[2025-03-25 12:31:23.850][INFO][1][h3r2q1l6] Hybrid cpu=1.00%,113MB, cid=1,1, timer=62,0,49, clock=0,48,1,0,0,0,0,0,0
[2025-03-25 12:31:23.850][INFO][1][h3r2q1l6] RTC: Server conns=2, rpkts=(1,rtp:0,stun:1,rtcp:1), spkts=(1,rtp:0,stun:1,rtcp:0), fid=(id:0,fid:1,ffid:0,addr:1,faddr:1)

[duiniuluantanqin]

Retrieve the latest code and refer to the Audio Only example in the demo. Upon testing, it is confirmed to be effective. The SDP is as follows:

Generated offer: v=0
o=- 7794266072462960639 2 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0
a=extmap-allow-mixed
a=msid-semantic: WMS
m=audio 9 UDP/TLS/RTP/SAVPF 111 63 9 0 8 13 110 126
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:OHwZ
a=ice-pwd:aXc7O1ubh9OWHmHR4zOIFT34
a=ice-options:trickle
a=fingerprint:sha-256 67:FF:43:9D:3F:DC:E3:CC:FB:C9:4D:1E:C4:33:4F:33:75:C2:1B:D7:77:30:21:A1:BC:B7:5D:85:98:35:46:16
a=setup:actpass
a=mid:0
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=recvonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:111 opus/48000/2
a=rtcp-fb:111 transport-cc
a=fmtp:111 minptime=10;useinbandfec=1
a=rtpmap:63 red/48000/2
a=fmtp:63 111/111
a=rtpmap:9 G722/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:13 CN/8000
a=rtpmap:110 telephone-event/48000
a=rtpmap:126 telephone-event/8000

srs.sdk.js:628 Got answer:  v=0
o=SRS/7.0.30(Hang) 89953796552832 2 IN IP4 0.0.0.0
s=SRSPlaySession
t=0 0
a=ice-lite
a=group:BUNDLE 0
a=msid-semantic: WMS live/livestream
m=audio 9 UDP/TLS/RTP/SAVPF 111
c=IN IP4 0.0.0.0
a=ice-ufrag:h7z9ks97
a=ice-pwd:3f1377s03104w690rz077lbw8k5pt2v6
a=fingerprint:sha-256 8F:7A:ED:D5:7D:93:E3:E4:4B:AA:97:B0:BB:75:C3:F8:18:66:67:64:E1:B7:49:77:CA:1F:F2:2C:A7:12:CD:1A
a=setup:passive
a=mid:0
a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
a=sendonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:111 opus/48000/2
a=rtcp-fb:111 transport-cc
a=ssrc:205121050 cname:740g01l4f79t7tgq
a=ssrc:205121050 label:audio-070y8feo
a=candidate:0 1 udp 2130706431 172.29.156.66 8000 typ host generation 0

TRANS_BY_GPT4

[AronBuzogany]

@duiniuluantanqin Where can I find the demo? I cannot seem to reproduce this. I keep getting audio: null. Using https://ossrs.net/players/whep. I want to stream audio to the server, not from the server.

So client sends webrtc stream to the server and the server makes this audio stream public.