https://developers.google.com/cast/docs/reference/web_receiver/cast.framework.PlaybackConfig#manifestHandler
manifestHandler

read pssh box
take convert to hex and take 16 bytes 32 chars after 1210, that's your kid

function base64ToHex(str) {
  const raw = atob(str);
  let result = '';
  for (let i = 0; i < raw.length; i++) {
    const hex = raw.charCodeAt(i).toString(16);
    result += (hex.length === 2 ? hex : '0' + hex);
  }
  return result.toUpperCase();
}

000000327073736800000000EDEF8BA979D64ACEA3C827DCD51D21ED000000121210 DB3505A999CE4078BEC73DA121BDC28F


https://stackoverflow.com/questions/54514961/how-to-renew-expired-drm-license-in-cast-receiver-player/55401570#55401570

can we get the new token before playback starts and after? manifest?

https://github.com/radiantmediaplayer/rmp-cast-receiver/blob/master/js/dev/player.js

https://github.com/googlecast/CastReceiver

https://github.com/NicePeopleAtWork/NicePlayers/blob/master/javascript/Chromecast/example/README.md