Async WebRTC recvonly vs offerToReceive

by jib1

HTML

<video id="video1" height="120" width="160" autoplay muted></video>
<video id="video2" height="120" width="160" autoplay></video><br>
<div id="div"></div>
<script src="https://webrtc.github.io/adapter/adapter-latest.js"></script>

JavaScript

let log = msg => div.innerHTML += msg + "<br>";
let gUM = c => navigator.mediaDevices.getUserMedia(c);
let pc1 = new RTCPeerConnection(), pc2 = new RTCPeerConnection();

(async () => {
  let stream = video1.srcObject = await gUM({audio: true});
  pc1.addTrack(stream.getTracks()[0], stream);
  await pc1.negotiate(true);
  log("here");
  await pc1.negotiate(false);
})().catch(e => log(e));

pc1.onicecandidate = e => pc2.addIceCandidate(e.candidate);
pc2.onicecandidate = e => pc1.addIceCandidate(e.candidate);
pc1.oniceconnectionstatechange = e => log(pc1.iceConnectionState);

let dumpDirections = (msg, sdp) => sdp.split('\r\nm=').slice(1).forEach(mline =>
  log(msg + ": 1 " + mline.split(' ')[0] +
      ": " + mline.match(/\r\na=(sendrecv|sendonly|recvonly|inactive)/)[1]));

pc1.negotiate = async offerToReceiveVideo => {
  await pc1.setLocalDescription(await pc1.createOffer({offerToReceiveVideo}));
  dumpDirections("pc1.localDesc", pc1.localDescription.sdp);
  await pc2.setRemoteDescription(pc1.localDescription);
  dumpDirections("pc2.remoteDesc", pc2.remoteDescription.sdp);
  await pc2.setLocalDescription(await pc2.createAnswer());
  await pc1.setRemoteDescription(pc2.localDescription);
}
pc2.onaddstream = e => video2.srcObject = e.stream;