var supports_autoplay = function(cb) {

  var r = [];

  // try to play video
  var v = document.createElement("video");
  v.paused = true;
  var vp = "play" in v && v.play();
  r.video = !v.paused || "Promise" in window && vp instanceof Promise;

  // try to play audio
  var a = document.createElement("audio");
  a.paused = true;
  "play" in a && a.play();
  r.audio = !a.paused;

  cb(r);

};