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. 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 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 | 6 webkit | 28 webkit |
Unprefixed | ? | (Yes) | (Yes) |