Web/API/AudioParam/exponentialRampToValueAtTime

From Get docs

The exponentialRampToValueAtTime() method of the AudioParam Interface schedules a gradual exponential change in the value of the AudioParam. The change starts at the time specified for the previous event, follows an exponential ramp to the new value given in the value parameter, and reaches the new value at the time given in the endTime parameter.


Note: Exponential ramps are considered more useful when changing frequencies or playback rates than linear ramps because of the way the human ear works.


Syntax

var AudioParam = AudioParam.exponentialRampToValueAtTime(value, endTime)

Parameters

value
A floating point number representing the value the AudioParam will ramp to by the given time.
endTime
A double representing the exact time (in seconds) after the ramping starts that the changing of the value will stop.

Returns

A reference to this AudioParam object. In some browsers older implementations of this interface return void.

Examples

In this example, we have a media source with two control buttons (see the audio-param repo for the source code, or [[../../../../../../../mdn.github.io/webaudio-examples/audio-param/index|view the example live]].) When these buttons are pressed, exponentialRampToValueAtTime() is used to fade the gain value up to 1.0, and down to 0, respectively. This is pretty useful for fade in/fade out effects:

// 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 expRampPlus = document.querySelector('.exp-ramp-plus');
var expRampMinus = document.querySelector('.exp-ramp-minus');

// Create a MediaElementAudioSourceNode
// Feed the HTMLMediaElement into it
var source = audioCtx.createMediaElementSource(myAudio);

// Create a gain node and set its gain value to 0.5
var gainNode = audioCtx.createGain();

// connect the AudioBufferSourceNode to the gainNode
// and the gainNode to the destination
gainNode.gain.setValueAtTime(0, audioCtx.currentTime);
source.connect(gainNode);
gainNode.connect(audioCtx.destination);

// set buttons to do something onclick
expRampPlus.onclick = function() {
  gainNode.gain.exponentialRampToValueAtTime(1.0, audioCtx.currentTime + 2);
}

expRampMinus.onclick = function() {
  gainNode.gain.exponentialRampToValueAtTime(0.01, audioCtx.currentTime + 2);
}

Note: A value of 0.01 was used for the value to ramp down to in the last function rather than 0, as an invalid or illegal string error is thrown if 0 is used — the value needs to be positive.


Specifications

Specification Status Comment
Web Audio APIThe definition of 'exponentialRampToValueAtTime' 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
exponentialRampToValueAtTime Chrome

Full support 14

Edge

Full support 12

Firefox Partial support 25

Notes'

Partial support 25

Notes'

Notes' Does not work (see bug 1171438 and bug 1567777).

IE

No support No

Opera

Full support 15

Safari

Full support 6

WebView Android

Full support Yes

Chrome Android Partial support 18

Notes'

Partial support 18

Notes'

Notes' This sets the target volume at the specified time, but it doesn’t ramp to it, causing this function to behave like setValueAtTime().

Firefox Android Partial support 26

Notes'

Partial support 26

Notes'

Notes' Does not work (see bug 1171438 and bug 1567777).

Opera Android

Full support 14

Safari iOS

Full support Yes

Samsung Internet Android

Full support 1.0

Legend

Full support  
Full support
Partial support  
Partial support
No support  
No support
See implementation notes.'
See implementation notes.


See also