Canvas视频

stream = canvas.captureStream();
recorder = new MediaRecorder(stream, {
  mimeType: 'video/webm'
});
recorder.addEventListener('dataavailable', e => {
  if (e.data && e.data.size) {
    data.push(e.data);
  }
});
recorder.addEventListener('stop', () => {
  const url = URL.createObjectURL(new Blob(data, {
    type: 'video/webm'
  }));
  canvas.style.display = 'none'
  document.querySelector('#video-container').style.display = 'block'
  document.querySelector('#video-container').src = url;
  document.querySelector('#video-container').play();
});