The createMediaStreamSource() method of the AudioContext Interface is used to create a new MediaStreamAudioSourceNode object, given a media stream (say, from a navigator.getUserMedia instance), the audio from which can then be played and manipulated.

For more details about media stream audio source nodes, check out the MediaStreamAudioSourceNode reference page.


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


A MediaStream object that you want to feed into an audio processing graph to manipulate.


A MediaStreamAudioSourceNode.


In this example, we grab a media (audio + video) stream from navigator.getUserMedia, feed the media into a <video> element to play then mute the audio, but then also feed the audio into a MediaStreamAudioSourceNode. Next, we feed this source audio into a low pass BiquadFilterNode (which effectively serves as a bass booster), then a AudioDestinationNode.

The range slider below the <video> element controls the amount of gain given to the lowpass filter — increase the value of the slider to make the audio sound more bass heavy!

Note: You can see this example running live, or view the source.

// fork getUserMedia for multiple browser versions, for those
// that need prefixes

navigator.getUserMedia = (navigator.getUserMedia ||
                          navigator.webkitGetUserMedia ||
                          navigator.mozGetUserMedia ||

// define other variables

var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var myAudio = document.querySelector('audio');
var pre = document.querySelector('pre');
var video = document.querySelector('video');
var myScript = document.querySelector('script');
var range = document.querySelector('input');

// Create variables to store mouse pointer Y coordinate
// and HEIGHT of screen
var CurY;
var HEIGHT = window.innerHeight;

// getUserMedia block - grab stream
// put it into a MediaStreamAudioSourceNode
// also output the visuals into a video element

if (navigator.getUserMedia) {
   console.log('getUserMedia supported.');
   navigator.getUserMedia (
      // constraints: audio and video for this app
         audio: true,
         video: true

      // Success callback
      function(stream) {
         video.src = (window.URL && window.URL.createObjectURL(stream)) || stream;
         video.onloadedmetadata = function(e) {
            video.muted = 'true';

         // Create a MediaStreamAudioSourceNode
         // Feed the HTMLMediaElement into it
         var source = audioCtx.createMediaStreamSource(stream);

          // Create a biquadfilter
          var biquadFilter = audioCtx.createBiquadFilter();
          biquadFilter.type = "lowshelf";
          biquadFilter.frequency.value = 1000;
          biquadFilter.gain.value = range.value;

          // connect the AudioBufferSourceNode to the gainNode
          // and the gainNode to the destination, so we can play the
          // music and adjust the volume using the mouse cursor

          // Get new mouse pointer coordinates when mouse is moved
          // then set new gain value

          range.oninput = function() {
              biquadFilter.gain.value = range.value;


      // Error callback
      function(err) {
         console.log('The following gUM error occured: ' + err);
} else {
   console.log('getUserMedia not supported on your browser!');

// dump script to pre element

pre.innerHTML = myScript.innerHTML;

Note: As a consequence of calling createMediaStreamSource(), audio playback from the media stream will be re-routed into the processing graph of the AudioContext. So playing/pausing the stream can still be done through the media element API and the player controls.



Specification Status Comment
Web Audio API
The definition of 'createMediaStreamSource()' in that specification.
Working Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 10.0webkit 25.0 (25.0)  No support 15.0webkit
22 (unprefixed)
Feature Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support ? 26.0 1.2 ? ? ? 33.0

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

API Audio AudioContext createMediastreamSource Method Reference Web Audio API