The setValueAtTime()
method of the AudioParam
interface schedules an instant change to the AudioParam
value at a precise time, as measured against AudioContext.currentTime
. The new value is given in the value parameter.
Syntax
var AudioParam = AudioParam.setValueAtTime(value, startTime)
Parameters
- value
- A floating point number representing the value the AudioParam will change to at the given time.
- startTime
- A double representing the time (in seconds) after the
AudioContext
was first created that the change in value will happen. ATypeError
is thrown if this value is negative.
Returns
A reference to this AudioParam
object. In some browsers older implementations of this interface return void.
Examples
This simple example features a media element source with two control buttons (see our webaudio-examples repo for the source code, or [[../../../../../../../mdn.github.io/webaudio-examples/audio-param/index|view the example live]]). When the buttons are pressed, the currGain
variable is incremented/decremented by 0.25, then the setValueAtTime()
method is used to set the gain value equal to currGain
, one second from now (audioCtx.currentTime + 1
.)
// create audio context var AudioContext = window.AudioContext || window.webkitAudioContext; var audioCtx = new AudioContext(); // set basic variables for example var myAudio = document.querySelector('audio'); var pre = document.querySelector('pre'); var myScript = document.querySelector('script'); pre.innerHTML = myScript.innerHTML; var targetAtTimePlus = document.querySelector('.set-target-at-time-plus'); var targetAtTimeMinus = document.querySelector('.set-target-at-time-minus'); // Create a MediaElementAudioSourceNode // Feed the HTMLMediaElement into it var source = audioCtx.createMediaElementSource(myAudio); // Create a gain node and set it's gain value to 0.5 var gainNode = audioCtx.createGain(); gainNode.gain.value = 0.5; var currGain = gainNode.gain.value; // connect the AudioBufferSourceNode to the gainNode // and the gainNode to the destination source.connect(gainNode); gainNode.connect(audioCtx.destination); // set buttons to do something onclick targetAtTimePlus.onclick = function() { currGain += 0.25; gainNode.gain.setValueAtTime(currGain, audioCtx.currentTime + 1); } targetAtTimeMinus.onclick = function() { currGain -= 0.25; gainNode.gain.setValueAtTime(currGain, audioCtx.currentTime + 1); }
Specifications
Specification | Status | Comment |
Web Audio APIThe definition of 'setValueAtTime' in that specification. | Working Draft |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
setValueAtTime
|
Chrome
Full support 14 |
Edge
Full support 12 |
Firefox
Full support 25 |
IE
No support No |
Opera
Full support 15 |
Safari
Full support 6 |
WebView Android
Full support Yes |
Chrome Android
Full support 18 |
Firefox Android
Full support 26 |
Opera Android
Full support 14 |
Safari iOS
Full support Yes |
Samsung Internet Android
Full support 1.0 |
Legend
- Full support
- Full support
- No support
- No support
See also
AudioParam.setValueAtTime() by Mozilla Contributors is licensed under CC-BY-SA 2.5.