WebRtc audio with webrtc-stream-manager v2

Answered

Jean-Baptiste Bouillet

August 28, 2026 13:46

Hello,
I'm trying to get audio on a camera using the webrtc-stream-manager-v2 but my stream has only one track and it's a video only.
On track event, I checked the track but it's only video, the streams var contains only one stream with one video track.
I succeeded getting deeper recreating a stream with all available tracks using the RTCPeerConnection but these are private members:

const stream = new MediaStream();

((cameraStream.connection as any).basePc.pc as RTCPeerConnection).getReceivers().forEach(r => {

if (r.track) {

stream.addTrack(r.track);

}

});

In my example there were 2 receivers with a track each (1 for audio and 1 for video).
Is there a better way to have a stream with all the track combined and not only the video one?

Regards,
Jean-Baptiste

 

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• 

  Ichiro

  • Network Optix team

  August 31, 2026 08:41

  Hi 
   

  Thanks for your question. Two separate things here.

  At the SDP level it isn't a library choice. The library is the answerer, not the offerer. The Nx server sends the offer and peer-connection.js  does setRemoteDescription then createAnswer. Under unified-plan, audio and video are separate m-lines, so ontrack fires once per track. Any WebRTC receiver gets two tracks by-design.

  At the library level the split is deliberate and video-only. CameraConnection ignores the server's stream grouping and builds its own managedStream, then emits streams: [this.managedStream] instead of event.streams. 

  Reason: it keeps two live peer connections (low-res base, high-res upgrade) and swaps the video track in place so srcObject identity never changes and you don't get a black flash on quality switches. That swap is inherently per-track. The MSE path forces it too, since video there comes from MseRenderer's captureStream(), not from the RTP track.

  If you need the audio track, PeerConnectionWrapper re-emits event.streams untouched one layer down. 

   

  So, in fact, you have done the proper implementation. 
  Thanks for your questions and understanding.

   

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