How to create a MediaStream from a uploaded audio file or a audio file URL using javascript?

Question

I know how to use navigator.getUserMedia to get the audio stream from the browser and system's default input device(a microphone). But what if I would like to get the MediaStream from an uploaded audio file or an audio file URL?

Appreciate if can provide a code example.

Answer 1

Two ways that come to my mind directly:

• three liner with MediaElement.captureStream():

const audio = new Audio(url);
const stream = audio.captureStream();
audio.play(); // stream now has input

// more than two lines actually in stacksnippets®
const audio = new Audio("https://upload.wikimedia.org/wikipedia/en/d/dc/Strawberry_Fields_Forever_(Beatles_song_-_sample).ogg");
audio.loop = true;
audio.crossOrigin = 'anonymous';
audio.play();

const stream = audio.captureStream ? 
  audio.captureStream() :
  audio.mozCaptureStream ?
    audio.mozCaptureStream() :
    null;
// feed our visible receiver with this stream
receiver.srcObject = stream;
console.log(stream.toString());

<audio id="receiver" controls></audio>

• a bit more with AudioContext.createMediaStreamDestination() and AudioContext.createMediaElementSource():

const audio = new Audio(url);
const ctx = new (window.AudioContext || window.webkitAudioContext)();
const stream_dest = ctx.createMediaStreamDestination();
const source = ctx.createMediaElementSource(audio);
source.connect(stream_dest);

const stream = stream_dest.stream;
audio.play();

const audio = new Audio("https://upload.wikimedia.org/wikipedia/en/d/dc/Strawberry_Fields_Forever_(Beatles_song_-_sample).ogg");
audio.loop = true;
audio.crossOrigin = 'anonymous';
audio.play();

const ctx = new (window.AudioContext || window.webkitAudioContext)();
const stream_dest = ctx.createMediaStreamDestination();
const source = ctx.createMediaElementSource(audio);
source.connect(stream_dest);

const stream = stream_dest.stream;

// feed our visible receiver with this stream
receiver.srcObject = stream;
console.log(stream.toString());

<audio id="receiver" controls></audio>