Web/API/AudioParam/setValueAtTime

From Get docs

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 [[../../../../../../../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

Update compatibility data on GitHub

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
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