Join MDN and developers like you at Mozilla's View Source conference, 12-14 September in Berlin, Germany. Learn more at https://viewsourceconf.org

AudioParam.setValueAtTime()

The setValueAtTime() method of the AudioParam Interface schedules an instant change to the value of the AudioParam 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. A TypeError 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 audio-param repo for the source code, or 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 API
The definition of 'setValueAtTime' in that specification.
Working Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 14 webkit 23 Not supported 15 webkit
22 (unprefixed)
6 webkit
Unprefixed (Yes)        
Feature Android Android Webview Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support Not supported (Yes) 25 1.2 Not supported Not supported webkit 28 webkit
Unprefixed ? (Yes)           (Yes)

See also

Document Tags and Contributors

 Contributors to this page: jpmedley, fscholz, chrisdavidmills
 Last updated by: jpmedley,