WebRTC pause and resume stream

Question

I am trying to use WebRTC to build a web application that needs to pause/resume the video/audio stream when some events trigger. I have tried the getTracks()[0].stop() but I am not sure how to resume the stream. Are there any advice on that? thanks

Solution 1

getTracks()[0].stop() is permanent.

Use getTracks()[0].enabled = false instead. To unpause getTracks()[0].enabled = true.

This will replace your video with black, and your audio with silence.

Try it (use https fiddle for Chrome):

var pc1 = new RTCPeerConnection(), pc2 = new RTCPeerConnection();

navigator.mediaDevices.getUserMedia({ video: true, audio: true })
  .then(stream => pc1.addStream(video1.srcObject = stream))
  .catch(log);

var mute = () => video1.srcObject.getTracks().forEach(t => t.enabled = !t.enabled);

var add = (pc, can) => can && pc.addIceCandidate(can).catch(log);
pc1.onicecandidate = e => add(pc2, e.candidate);
pc2.onicecandidate = e => add(pc1, e.candidate);

pc2.onaddstream = e => video2.srcObject = e.stream;
pc1.onnegotiationneeded = e =>
  pc1.createOffer().then(d => pc1.setLocalDescription(d))
  .then(() => pc2.setRemoteDescription(pc1.localDescription))
  .then(() => pc2.createAnswer()).then(d => pc2.setLocalDescription(d))
  .then(() => pc1.setRemoteDescription(pc2.localDescription))
  .catch(log);

var log = msg => div.innerHTML += "<br>" + msg;

<video id="video1" height="120" width="160" autoplay muted></video>
<video id="video2" height="120" width="160" autoplay></video><br>
<input type="checkbox" onclick="mute()">mute</input><div id="div"></div>
<script src="https://webrtc.github.io/adapter/adapter-latest.js"></script>

PeerConnections basically stop sending packets in this muted state, so it is highly efficient.

Solution 2

You should try using renegotiation, I believe the difference still exists how it is done in chrome and firefox:

• In chrome, you just call addStream or removeStream on the PeerConnection object to add/ remove the stream, then create and exchange sdp.

• In firefox, there is no direct removeStream, you need to use RTCRtpSender and addTrack and removeTrack methods, you can take a look at this question

Comments

[JSON]

The last sentence is unclear. Will "black video" and "silence" still use similar resources as before disabled (decoding/rendering, data transmission, etc)?

[jib]

@JSON I've updated the answer to clarify that it hardly uses any resources. I confirmed it using stats in this fiddle (requires Firefox for spec-stats atm). Thanks for catching that it was unclear.

[Javad Asoodeh]

Can you explain what happens to bandwidth?

[Javad Asoodeh]

I think i still receive track, but how can pause a particular transreceiver.sender(Audio/Video) from remote side with negotiation and without it ?

[Javad Asoodeh]

I changed direction attr from receiver side to 'inactive' and On the receiver side, the bandwidth decreased, do you think it's true way for pause audio/video ?

[jib]

@J4v4d Right, to pause from the remote end is a different question, and changing direction is one way to go there. See my blog post for the myriad ways to control a track remotely.

[Atif Shafi]

is there any way out for just pausing the steaming simply instead of receiving blank frames , because I am sending those frames to the backend for processing