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The MediaElementAudioSourceNode
interface represents an audio source consisting of an HTML5 <audio>
or <video>
element. It is an AudioNode
that acts as an audio source.
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. |
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.
Note: You can also view this example running live, or view the source.
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);
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.
Specification
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'MediaElementAudioSourceNode' in that specification. |
Working Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 14 webkit | 25 (25) | No support | 15 webkit 22 (unprefixed) |
6 webkit |
Feature | Android | Chrome | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | No support | 28 webkit | 25.0 (25) | 1.2 | No support | No support | 6 webkit |