RTCPeerConnection.addStream()

The RTCPeerConnection.addStream() method adds a MediaStream as a local source of audio or video. If the negotiation already happened, a new one will be needed for the remote peer to be able to use it.

If the signalingState is set to "closed", an InvalidStateError is raised. If the signalingState is set to "stable", the event negotiationneeded is sent on the RTCPeerConnection.

Syntax

pc.addStream(mediaStream);

Parameters

mediaStream

A MediaStream object indicating the stream to add to the WebRTC peer connection.

Return value

None.

Example

navigator.getUserMedia({video:true, audio:true}, function(stream) {
  var pc = new RTCPeerConnection();
  pc.addStream(stream);
});

Migration

Compatibility allowing [2], consider switching to using the addTrack() method instead:

navigator.getUserMedia({video:true, audio:true}, function(stream) {
  var pc = new RTCPeerConnection();
  stream.getTracks().forEach(function(track) {
    pc.addTrack(track, stream);
  });
});

The newer addTrack() API avoids confusion over whether later changes to the track-makeup of a stream affects a peer connection (they does not).

The exception is in Chrome, where addStream does make the peer connection sensitive to later stream changes (though such changes do not fire the negotiationneeded event). If you are relying on the Chrome behavior, note that other browsers do not have it. You can write web compatible code using feature detection instead:

// Add a track to a stream and the peer connection said stream was added to:
stream.addTrack(track);
if (pc.addTrack) {
  pc.addTrack(track, stream);
} else {
  // If you have code listening for negotiationneeded events:
  setTimeout(() => pc.dispatchEvent(new Event('negotiationneeded')));
}
// Remove a track from a stream and the peer connection said stream was added to:
stream.removeTrack(track);
if (pc.removeTrack) {
  pc.removeTrack(pc.getSenders().find(sender => sender.track == track));
} else {
  // If you have code listening for negotiationneeded events:
  setTimeout(() => pc.dispatchEvent(new Event('negotiationneeded')));
}

Specifications

Browser compatibility

[1] Though this method is not prefixed, the interface it belongs to was until Chrome 56.

[2] Chrome does not yet support addTrack(), this method's replacement. However, it is available through the adapter.js polyfill.

[3] Although this property's name isn't prefixed, the RTCPeerConnection interface was prefixed as MozRTCPeerConnection until Firefox 44.

See also

• WebRTC