Webrtc：无法在Firefox中看到远程流，但在Chrome中可以使用

Question

我最近重新构建了我的webRtc代码，取代了一些已弃用的API和其他一些重组。它继续在Chrome中运行，但不再在Firefox中运行。代码的基本结构如下所示：

navigator.mediaDevices.getUserMedia ({ audio: true, video: true })
  .then(function(localMediaStream) {

     //Show local media
     document.getElementById("myVideoMedia").srcObject = localMediaStream;

     //create peerConnection
     peerConnection = new RTCPeerConnection({
       "iceServers": [{"url": "stun:stun.l.google.com:19302"}]
     });

     peerConnection.ontrack = function(event) {
       remoteStream = event.streams[0];
       document.getElementById("remoteVideoElement").srcObject = remoteStream;
     };

      peerConnection.onicecandidate = function (event) {
         if (event.candidate != null) {
           //Send ice candidate to peer connection..
         }  
      };

      peerConnection.addStream(localMediaStream);

      //Show remote media
      document.getElementById("remoteVideoElement").srcObject = remoteStream;

     //If caller, send video invite to callee to do the above in its browser
     //if callee, having received video invite, send message to caller to request sdpOffer


});


//When (on caller's side) request to send sdpOffer is received
 var sdpOffer = new RTCSessionDescription (offer);
 peerConnection.setLocalDescription (sdpOffer)
    .then (function() {
       //send sdpOffer
    });


//When (on callee's side) sdpOffer is received 
peerConnection.setRemoteDescription(remoteSdpOffer)
  .then(function() { 
     peerConnection.createAnswer()
       .then(function(sdpAnswer) {
        var sdpAnswer = new RTCSessionDescription(sdpAnswer);
        //send sdpAnswer 
        peerConnection.setLocalDescription(sdpAnswer)
          .then(function(){
             ...
        })

//When ICE candidate is received
peerConnection.addIceCandidate(new RTCIceCandidate(iceCandidate))
  .then(function() { //console.log("Remote Ice candidate added");
})
.catch(function(err) {...});

无论Firefox浏览器是呼叫者还是被叫者，都不会在Firefox中看到远程视频。我怀疑它与事件处理程序的一些排序有关但无法找到哪一个......