Errors when ICE Candidates are received before answer is sent
google-chrome, webrtc
Solution
After I wrote this question an answer came into my mind... There is no need for attaching local stream before receiving ICE candidates, but `remoteDescription` should be set (which should be done at the moment of receiving offer). In my code I waited with setting `remoteDescription` and sending answer until browser gets the local stream.
Problem
I'm establishing WebRTC connection on Chrome 23. To attach local stream you need to allow browser to use the camera and microphone. On the caller side I'm checking if local stream can be obtained and I'm not sending offer until this moment. Then offer is sent and the browser immediately starts to send ICE candidates. Then if remote browser didn't obtained local media stream yet I get `SYNTAX_ERR: DOM Exception 12` on `peerConnection.addIceCandidate(candidate)` for every ICE candidate received. I checked documentation on `addIceCandidate` but there is no info about prerequisites. I think I can delay sending ICE candidates from offerer by delaying it and waiting for signal that remote client added local stream, but this is additional communication needed and doesn't look right. Can I somehow add remote ICE candidates to `webkitRTCPeerConnection` before answer is sent and local media stream is attached?