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                <select id="video-devices">
  <option>Video (Default)</option>
<select id="audio-devices">
  <option>Audio (Default)</option>

<button id="start">Start</button>
<button id="shot">Take a Screenshot</button>

<div class="results">
<div id="stream"></div>
<div id="screenshot"></div>



                body {

.results {
  display: flex;
.results div:first-child {
  flex-basis: 50%;
.results div:last-child {
  flex-basis: 50%;
.results video,
.results canvas{
  width: 100%;
  border: 1px solid #000;



                const init = async () => {
  const startButton = document.querySelector("button#start");
  const shotButton = document.querySelector("button#shot");
  const audioDeviceSelect = document.querySelector<HTMLSelectElement>("select#audio-devices");
  const videoDeviceSelect = document.querySelector<HTMLSelectElement>("select#video-devices");
  const videoContainer = document.querySelector<HTMLDivElement>("div#stream");
  const canvasContainer = document.querySelector<HTMLDivElement>("div#screenshot");

  // 先に許可を貰わないとenumerateDevicesが返すデバイス名(label)を取得できない
  await navigator.mediaDevices.getUserMedia({video: true, audio: true});
  const devices = await navigator.mediaDevices.enumerateDevices();
  devices.forEach((device) => {
    console.log(device.kind + ": " + device.label + " id = " + device.deviceId);
    const option = document.createElement("option");
    option.text = device.label;
    option.value = device.deviceId;

    if (device.kind === "audioinput") {
    } else if (device.kind === "videoinput") {

  const getSelectedVideo = () => {
    return videoDeviceSelect.value;

  const getSelectedAudio = () => {
    return audioDeviceSelect.value;
  let captureStream: MediaStream;
  startButton.addEventListener("click", async () => {
    videoContainer.innerHTML = '';

    captureStream = await navigator.mediaDevices.getUserMedia({video: { deviceId: getSelectedVideo(), width: 1920, height: 1080 }, audio: {deviceId: getSelectedAudio()}});
    const video = document.createElement("video");
    video.autoplay = true;
    video.srcObject = captureStream;

  shotButton.addEventListener('click', async () => {
    const videoTrack = captureStream.getVideoTracks()[0];
    const imageCapture = new ImageCapture(videoTrack);
    const imageBitmap = await imageCapture.grabFrame();
    console.log('Grabbed frame:', imageBitmap);
    canvasContainer.innerHTML = '';
    const canvas = document.createElement("canvas");
    canvas.width = imageBitmap.width;
    canvas.height = imageBitmap.height;
    canvas.getContext('2d').drawImage(imageBitmap, 0, 0);