Article WebRTC two-way transceiver replaceTrack

HTML

<h3 style="border-bottom: 1px solid">Original canvas</h3>
<canvas id="canvas" width="100" height="100"></canvas>
<script>
function localPeerConnectionLoop(cfg = {sdpSemantics: 'unified-plan'}) {
  const setD = (d, a, b) => Promise.all([a.setLocalDescription(d), b.setRemoteDescription(d)]);
  return [0, 1].map(() => new RTCPeerConnection(cfg)).map((pc, i, pcs) => Object.assign(pc, {
    onicecandidate: e => e.candidate && pcs[i ^ 1].addIceCandidate(e.candidate),
    onnegotiationneeded: async e => {
      try {
        await setD(await pc.createOffer(), pc, pcs[i ^ 1]);
        await setD(await pcs[i ^ 1].createAnswer(), pcs[i ^ 1], pc);
      } catch (e) {
        console.log(e);
      }
    }
  }));
}
</script>
<h3 style="border-bottom: 1px solid">Local peer (PC1)</h3>
<video id="videoA" muted width="100" height="100"></video>

<h3 style="border-bottom: 1px solid">Remote peer (PC2)</h3>
<video id="videoC" muted width="100" height="100"></video>
<label> Change jitterBufferDelayHint
<input type="number" value="1" id="$dur">
</label>

CSS

canvas, video {
  background: #000;
}

JavaScript

import('https://jimmy.warting.se/packages/dummycontent/canvas-clock.js')
.then(({AnalogClock}) => {
  const {canvas} = new AnalogClock(100)
  document.querySelector('canvas').replaceWith(canvas)
  
  const [pc1, pc2] = localPeerConnectionLoop()
  const canvasStream = canvas.captureStream(200)

  videoA.srcObject = canvasStream
  videoA.play()

  pc1.addTransceiver(canvasStream.getTracks()[0], {
    streams: [ canvasStream ]
  })

  pc2.onaddstream = (evt) => {
    videoC.srcObject = evt.stream
    videoC.play()
  }

  $dur.onchange = () => {
    pc2.getReceivers()[0].playoutDelayHint = $dur.valueAsNumber
  }
})