AudioParam.setValueAtTime()

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. 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 webaudio-examples 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

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
setValueAtTime
14
12
25
No
15
6
≤37
18
25
14
6
1.0

See also

© 2005–2021 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/AudioParam/setValueAtTime