javascript - MediaStream 未处理的 promise 拒绝 : [object DOMError] (in Safari 11)

Question

我在以下初始化 WebRTC 的方法中收到了 Safari Tech Preview 11 中未处理的 Promise Rejection。具体来说，当我将 MediaStream 分配给视频元素时会发生这种情况:video.srcObject = event.stream; - 堆栈跟踪显示这一行是抛出异常。我无法使用 try/catch.

捕获异常

异常仅发生在 Safari 11 中(不会发生在 Chrome 中)。

方法如下:

initWebRTC(p){
    var self = this;
    return new Promise((resolve, reject) => {

      self.state.connection = new RTCMultiConnection();
      self.state.connection.socketMessageEvent = 'webrtc-firebase';
      self.state.connection.setCustomSocketHandler(FirebaseConnection);
      self.state.connection.firebase = 'webrtc-firebase'; 
      self.state.connection.enableFileSharing = true; 
      self.state.connection.session = {
        audio: true,
        video: true,
        data: true
      };
      self.state.connection.sdpConstraints.mandatory = {
        OfferToReceiveAudio: true,
        OfferToReceiveVideo: true
      };
      self.state.connection.onstream = function(event) {
          console.log('event.mediaElement',event.mediaElement);
          console.log('event.stream',event.stream);

          var videoContainer = document.getElementById('videoContainer');
          var video = event.mediaElement;
          if (!window.safari){
            var source = document.createElement("source");
            source.srcObject = event.stream;
            video.appendChild(source);
          } else { // Safari
            try{
              video.srcObject = event.stream; // this is the line that throws the exception
            }catch(e){ //unable to catch the exception
              console.log('exception',e);
            }
          }
          videoContainer.appendChild(video);

          var playPromise = video.play();
          if (playPromise !== undefined) { // not a Promise in some browsers
            playPromise.catch(function(error) {
            });
          }
          setTimeout(function() {
            var playPromise = video.play();
            if (playPromise !== undefined) {
              playPromise.catch(function(error) {
              });
            }
          }, 5000);
      };
      resolve();
    });
  }

不确定这是否有帮助，但这是痕迹:

[Error] Unhandled Promise Rejection: [object DOMError]
    (anonymous function)
    rejectPromise
    onstream (index.js:5787) // this is the video.srcObject = event.stream; line
    (anonymous function) (RTCMultiConnection.js:4092)
    getRMCMediaElement (RTCMultiConnection.js:1113)
    onGettingLocalMedia (RTCMultiConnection.js:4064)
    onGettingLocalMedia (RTCMultiConnection.js:4984)
    streaming (RTCMultiConnection.js:3289)
    (anonymous function) (RTCMultiConnection.js:3358)
    promiseReactionJob

如有任何帮助，我们将不胜感激。谢谢!

Answer 1

Safari 11 默认阻止自动播放任何有声视频 (source)。

我相信 video 元素带有自动播放属性。当您为它设置 srcObject 时，它会尝试播放视频——然后被 Safari 阻止。这就是您看到错误的原因。

您可以尝试从视频元素中删除 autoplay，然后您可以在 playPromise.catch 中捕获它。