javascript - WebRTC both remote and local video is displayed with local stream

Question

hello i am newbie in WebRTC and i tried this code

  const yourVideo = document.querySelector("#face_cam_vid");
 const theirVideo = document.querySelector("#thevid");

 (async () => {
 if (!("mediaDevices" in navigator) || !("RTCPeerConnection" in window)) {
  alert("Sorry, your browser does not support WebRTC.");
  return;
 }
  const stream = await navigator.mediaDevices.getUserMedia({video: true, 
  audio: true});
  yourVideo.srcObject = stream;

  const configuration = {
  iceServers: [{urls: "stun:stun.1.google.com:19302"}]
  };
const yours = new RTCPeerConnection(configuration);
const theirs = new RTCPeerConnection(configuration);

for (const track of stream.getTracks()) {
  yours.addTrack(track, stream);
}
theirs.ontrack = e => theirVideo.srcObject = e.streams[0];

yours.onicecandidate = e => theirs.addIceCandidate(e.candidate);
theirs.onicecandidate = e => yours.addIceCandidate(e.candidate);

const offer = await yours.createOffer();
await yours.setLocalDescription(offer);
await theirs.setRemoteDescription(offer);

const answer = await theirs.createAnswer();
await theirs.setLocalDescription(answer);
await yours.setRemoteDescription(answer);
})();

and it works but partly https://imgur.com/a/nG7Xif6 . in short i am creating ONE-to-ONE random video chatting like in omegle but this code displays both "remote"(stranger's) and "local"("mine") video with my local stream but all i want is , user wait for second user to have video chat and when third user enters it should wait for fourth and etc. i hope someone will help me with that

Answer 1

You're confusing a local-loop demo—what you have—with a chat room.

A local-loop demo is a short-circuit client-only proof-of-concept, linking two peer connections on the same page to each other. Utterly useless, except to prove the API works and the browser can talk to itself.

It contains localPeerConnection and remotePeerConnection—or pc1 and pc2—and is not how one would typically write WebRTC code. It leaves out signaling.

Signaling is hard to demo without a server, but I show people this tab demo. Right-click and open it in two adjacent windows, and click the Call! button on one to call the other. It uses localSocket, a non-production hack I made using localStorage for signaling.

Just as useless, a tab-demo looks more like real code:

const pc = new RTCPeerConnection();

call.onclick = async () => {
  video.srcObject = await navigator.mediaDevices.getUserMedia({video:true, audio:true});
  for (const track of video.srcObject.getTracks()) {
    pc.addTrack(track, video.srcObject);
  }
};

pc.ontrack = e => video.srcObject = e.streams[0];
pc.oniceconnectionstatechange = e => console.log(pc.iceConnectionState);
pc.onicecandidate = ({candidate}) => sc.send({candidate});
pc.onnegotiationneeded = async e => {
  await pc.setLocalDescription(await pc.createOffer());
  sc.send({sdp: pc.localDescription});
}

const sc = new localSocket();
sc.onmessage = async ({data: {sdp, candidate}}) => {
  if (sdp) {
    await pc.setRemoteDescription(sdp);
    if (sdp.type == "offer") {
      await pc.setLocalDescription(await pc.createAnswer());
      sc.send({sdp: pc.localDescription});
    }
  } else if (candidate) await pc.addIceCandidate(candidate);
}

There's a single pc—your half of the call—and there's an onmessage signaling callback to handle the timing-critical asymmetric offer/answer negotiation correctly. Same JS on both sides.

This still isn't a chat-room. For that you need server logic to determine how people meet, and a web socket server for signaling. Try this tutorial on MDN which culminates in a chat demo.