Chrome Extension tabCapture API Audio Stream to Play in HTML Page

Question

I am creating a chrome extension which captures audio from a tab using the chrome tabCapture API. I would like to play this audio stream in another html page in hopes of eventually creating a visualizer for it.

I capture the audio in a background script like so

chrome.browserAction.onClicked.addListener(function(activeTab) {
  var constraints = {
    audio: true,
    video: false,
  };

  var visualizerPage = chrome.extension.getURL("/views/visualizer.html");

  chrome.tabCapture.capture(constraints, function(stream) {
    console.log("\ngot stream");
    console.log(stream);

    chrome.tabs.create({
      url: visualizerPage
    }, function(tab) {

      chrome.tabs.sendMessage(tabID, {
        "message": "stream",
        "stream": stream
      });
    });
  });

the audio stream is captured from whatever page the extension was clicked on. Another tab is opened, and the audio stream is sent to it as a message.

The javascript for the visualizer.html page is

function loadStream(stream) {
  // what do I have to put here to play the stream?
}

chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
  if (request.message === "stream") {
    var stream = request.stream;

    if (!stream) {
      console.log("stream is null");
      return;
    }

    console.log(stream);
    loadStream(stream);
  }
  else if (request.message === "statusChanged") {
    console.log("statusChanged");
  }
});

What I have so far is to load the audio stream into the web audio api using an audio context

var context = new AudioContext();
var source = context.createMediaStreamSource(stream);

but the script just hangs when trying to create the source.

The problem is I am not really sure what type the stream is (tabCapture api says its a LocalMediaStream).

How can I get the page to play the audio stream?

Answer 1

Try this in loadStream function:

var audio = new Audio();
audio.src = URL.createObjectURL(stream);
audio.play();