javascript - Chrome 扩展程序捕获选项卡音频

Question

我正在尝试创建一个 Chrome 扩展程序，它可以从事件选项卡捕获音频并将其发送到另一台服务器或通过 URL 访问它。

我正在使用 chrome.tabCapture.capture API并且可以成功获取标签页音频的MediaStream，但我不知道之后该做什么。

Chrome 文档没有关于 MediaStreams 的内容，所以我查看了一些文档 here并使用 JS 调试器查看可用的方法，但找不到将 MediaStream 发送到某处的方法。

Answer 1

现在可以使用 MediaRecorder 在 JS 中本地录制流。有demo here w3c 规范是 here

demo中的方法startRecording需要将window.stream设置为MediaStream实例。

// The nested try blocks will be simplified when Chrome 47 moves to Stable
var mediaRecorder;
var recordedBlobs;
window.stream = myMediaStreamInstance;
function startRecording() {
  var options = {mimeType: 'video/webm', bitsPerSecond: 100000};
  recordedBlobs = [];
  try {
    mediaRecorder = new MediaRecorder(window.stream, options);
  } catch (e0) {
    console.log('Unable to create MediaRecorder with options Object: ', e0);
    try {
      options = {mimeType: 'video/webm,codecs=vp9', bitsPerSecond: 100000};
      mediaRecorder = new MediaRecorder(window.stream, options);
    } catch (e1) {
      console.log('Unable to create MediaRecorder with options Object: ', e1);
      try {
        options = 'video/vp8'; // Chrome 47
        mediaRecorder = new MediaRecorder(window.stream, options);
      } catch (e2) {
        alert('MediaRecorder is not supported by this browser.\n\n' +
            'Try Firefox 29 or later, or Chrome 47 or later, with Enable experimental Web Platform features enabled from chrome://flags.');
        console.error('Exception while creating MediaRecorder:', e2);
        return;
      }
    }
  }
  console.log('Created MediaRecorder', mediaRecorder, 'with options', options);

  // do UI cleanup here
  mediaRecorder.onstop = function() {/** stop */};
  mediaRecorder.ondataavailable = function() {/** data avail */};
  mediaRecorder.start(10); // collect 10ms of data
  console.log('MediaRecorder started', mediaRecorder);
}

1. https://www.w3.org/TR/mediastream-recording/
2. https://simpl.info/mediarecorder/