为什么getuserMedia音频在Mac OS的Safari 11.1中不起作用

Question

我正在尝试播放webrtc DEMO引用的getUserMedia音频示例。

它可在所有浏览器上运行，但不适用于Mac OS的 Safari 11.1 。有趣的是，它可以在iPad的Safari上运行。

var tempStream;
// Put variables in global scope to make them available to the browser console.
const audio = document.querySelector('audio');

const constraints = window.constraints = {
  audio: true,
  video: true
};

function handleSuccess(stream) {
  const audioTracks = stream.getAudioTracks();
  tempStream = stream; // make variable available to browser console
}

function audioPlay() {
  audio.srcObject = tempStream;
  audio.play();
}

document.querySelector('#audioPlay').addEventListener('click', audioPlay);

navigator.mediaDevices.getUserMedia(constraints).then(handleSuccess);

<div id="container">
  <audio id="gum-local" controls></audio> <br />
  <button id="audioPlay"> <b> PLAY AUDIO </b>	</button>
</div>