<!DOCTYPE html>
<html>
<head><title>Loopback test</title></head>
<body>
  <video id="remoteVideo" autoplay muted></video>
<script>
var localStream, localPeerConnection, remotePeerConnection;
var remoteVideo = document.getElementById("remoteVideo");

function start() {
  navigator.getUserMedia = navigator.getUserMedia ||
    navigator.webkitGetUserMedia;
  navigator.getUserMedia(
    {
      audio:false,
      video:{
        "mandatory": {
          "minWidth": "1280",
          "minHeight": "720",
        }
      }
    },
    gotLocalStream,
    gotError);
}

function gotLocalStream(stream) {
  localStream = stream;
  var servers = null;

  localPeerConnection = new webkitRTCPeerConnection(servers);
  localPeerConnection.onicecandidate = gotLocalIceCandidate;

  remotePeerConnection = new webkitRTCPeerConnection(servers);
  remotePeerConnection.onicecandidate = gotRemoteIceCandidate;
  remotePeerConnection.onaddstream = gotRemoteStream;

  localPeerConnection.addStream(localStream);
  localPeerConnection.createOffer(gotLocalDescription, function(error) {});
}

function gotError(error) {
  console.log("navigator.getUserMedia error: ", error);
}

function gotRemoteStream(event) {
  remoteVideo.srcObject = event.stream;
}

function gotLocalDescription(description) {
  localPeerConnection.setLocalDescription(description);
  remotePeerConnection.setRemoteDescription(description);
  remotePeerConnection.createAnswer(gotRemoteDescription, function(error) {});
}

function gotRemoteDescription(description) {
  remotePeerConnection.setLocalDescription(description);
  localPeerConnection.setRemoteDescription(description);
}

function gotLocalIceCandidate(event) {
  if (event.candidate)
    remotePeerConnection.addIceCandidate(new RTCIceCandidate(event.candidate));
}

function gotRemoteIceCandidate(event) {
  if (event.candidate)
    localPeerConnection.addIceCandidate(new RTCIceCandidate(event.candidate));
}

window.onload=start;
</script>
</body>
</html>