FF61 - Audio not flowing when remote offer is added to peer connection before local streams

[Eric Green]

Hi Everyone,

We are seeing that starting in Firefox 61, the local media streams need to be added to the Peer Connection before the remote offer is added to the PC otherwise there will be dead air for audio. Video appears to not be affected by this. In the broken case we are seeing all WebRTC calls successfully return, and a valid SDP negotiation happen. We are seeing packets flow in both directions. Everything appears happy, but there is no audio being sent.

Broken Case - Results in muted audio being sent, but can hear other party:
getUserMedia
new PeerConnection
setRemoteDescription
addLocalStreams
getLocalDescription

Working Case - Results in full audio:
getUserMedia
new PeerConnection
addLocalStreams
setRemoteDescription
getLocalDescription

The broken case was previously working in FF 60.0.2 and earlier. Video appears to work in both instances. The order of which you add the local streams to the peer connection should not matter. We will adjust our code to compensate, but we believe that this is broken in Firefox and are hoping others can confirm and that it can be patched in a later release.

Thanks,
-Eric Green

[dame...@damencho.com]

Hi,

I think we are experiencing the same issue and a few days ago I opened an issue:
https://bugzilla.mozilla.org/show_bug.cgi?id=1472321

Regards
damencho