AudioContext: createMediaElementSource() method

The createMediaElementSource() method of the AudioContext Interface is used to create a new MediaElementAudioSourceNode object, given an existing HTML <audio> or <video> element, the audio from which can then be played and manipulated.

For more details about media element audio source nodes, check out the MediaElementAudioSourceNode reference page.

Syntax

js

createMediaElementSource(myMediaElement)

Parameters

myMediaElement

An HTMLMediaElement object that you want to feed into an audio processing graph to manipulate.

Return value

A MediaElementAudioSourceNode.

Examples

This simple example creates a source from an <audio> element using createMediaElementSource(), then passes the audio through a GainNode before feeding it into the AudioDestinationNode for playback. When the mouse pointer is moved, the updatePage() function is invoked, which calculates the current gain as a ratio of mouse Y position divided by overall window height. You can therefore increase and decrease the volume of the playing music by moving the mouse pointer up and down.

js

const audioCtx = new AudioContext();
const myAudio = document.querySelector("audio");

// Create a MediaElementAudioSourceNode
// Feed the HTMLMediaElement into it
const source = audioCtx.createMediaElementSource(myAudio);

// Create a gain node
const gainNode = audioCtx.createGain();

// Create variables to store mouse pointer Y coordinate
// and HEIGHT of screen
let curY;
const HEIGHT = window.innerHeight;

// Get new mouse pointer coordinates when mouse is moved
// then set new gain value
document.onmousemove = updatePage;

function updatePage(e) {
  curY = e.pageY;
  gainNode.gain.value = curY / HEIGHT;
}

// 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
source.connect(gainNode);
gainNode.connect(audioCtx.destination);

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

Specifications

Specification
Web Audio API
# dom-audiocontext-createmediaelementsource

Browser compatibility

BCD tables only load in the browser

See also