javascript - getUserMedia API无法从Chrome扩展程序捕获音频和视频

Question

我正在使用getUserMedia api捕获屏幕并记录来自chrome扩展程序的音频(两者一起)。 api捕获屏幕，记录视频，但不捕获音频。

Chrome版本:55

没有捕获音频的任何原因。 API是否有任何限制，还是需要使用任何其他API来捕获视频和音频？
请在下面找到代码片段。 (以下代码存在于background.js中)

(尝试将约束传递为音频:true，视频:true，但这没有用。它引发了错误。(错误-getUserMedia()失败:[对象NavigatorUserMediaError]))

chrome.desktopCapture.chooseDesktopMedia(['screen','audio'],
    function onAccessApproved(id) {     

    const constraints = { "video": {
             mandatory: {
                chromeMediaSource: 'desktop',       
                chromeMediaSourceId: id,        
                minWidth: 1280,
                minHeight: 720,                 
                maxWidth:1280,
                maxHeight:720
            }
            }, "audio" : {
             mandatory: {
                chromeMediaSource: 'desktop',       
            chromeMediaSourceId: id}} };                    

 navigator.mediaDevices.getUserMedia(constraints).then(gotMedia).catch(e => { console.error('getUserMedia() failed: ' + e); 
});

function gotMedia(stream) {

  theStream = stream;
  var video = document.createElement('video');
  video.src = URL.createObjectURL(stream);
  video.srcObject = stream;

  try {
    recorder = new MediaRecorder(stream, {mimeType : "video/webm"});
  } catch (e) {
    console.error('Exception while creating MediaRecorder: ' + e);
    return;
  }

  theRecorder = recorder;
  recorder.ondataavailable = 
      (event) => { recordedChunks.push(event.data); };
  recorder.start(100);


  stream.getVideoTracks()[0].onended = function () {
        download();
    };
}   


function download() {


  theRecorder.stop();
  theStream.getTracks().forEach(track => { track.stop(); });

  var blob = new Blob(recordedChunks, {type: "video/webm"});
  var url =  URL.createObjectURL(blob);
  var a = document.createElement("a");
  document.body.appendChild(a);
  a.style = "display: none";
  a.href = url;
  a.download = 'test.webm';
  a.click();
  // setTimeout() here is needed for Firefox.
  setTimeout(function() { URL.revokeObjectURL(url); }, 100); 
}

Answer 1

根据关于屏幕共享的webRTC Experiment's page，

Why Screen Sharing Fails?
[...]
2. On chrome, you requested audio-stream alongwith 'chromeMediaSource' – it is not permitted on chrome.

因此，这是不允许的。

您可以尝试仅对音频进行并行请求，然后将两个流与 MediaStream.addTrack() 合并，尽管我没有对其进行测试。
videoStream.addTrack(audioStream.getAudioTracks()[0])