MediaElementAudioSourceNode

A MediaElementSourceNode has no inputs and exactly one output, and is created using the AudioContext.createMediaElementSource method. The amount of channels in the output equals the number of channels of the audio referenced by the HTMLMediaElement used in the creation of the node, or is 1 if the HTMLMediaElement has no audio.

Number of inputs	0
Number of outputs	1
Channel count	defined by the media in the HTMLMediaElement passed to the AudioContext.createMediaElementSource method that created it.

Constructor

MediaElementAudioSourceNode.MediaElementAudioSourceNode()

Creates a new MediaElementAudioSourceNode instance.

Properties

Inherits properties from its parent, AudioNode.

Methods

Inherits methods from its parent, AudioNode.

Example

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.

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

pre.innerHTML = myScript.innerHTML;

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

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

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

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

document.onmousemove = updatePage;

function updatePage(e) {
    CurY = (window.Event) ? e.pageY : event.clientY + (document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop);

    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);

Specification

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

Browser compatibility

See also

• Using the Web Audio API