NOTE: both the example and live example are incorrect, see https://github.com/WebAudio/web-audio-api/issues/34
The linearRampToValueAtTime()
method of the AudioParam
Interface schedules a gradual linear change in the value of the AudioParam
. The change starts at the time specified for the previous event, follows a linear ramp to the new value given in the value
parameter, and reaches the new value at the time given in the endTime
parameter.
Syntax
var AudioParam = AudioParam.linearRampToValueAtTime(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.
Example
In this example, we have a media source with two control buttons (see the audio-param repo for the source code, or view the example live.) When these buttons are pressed, linearRampToValueAtTime()
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, although AudioParam.exponentialRampToValueAtTime()
is often said to be a bit more natural.
// 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 linearRampPlus = document.querySelector('.linear-ramp-plus'); var linearRampMinus = document.querySelector('.linear-ramp-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(); // 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 linearRampPlus.onclick = function() { gainNode.gain.linearRampToValueAtTime(1.0, audioCtx.currentTime + 2); } linearRampMinus.onclick = function() { gainNode.gain.linearRampToValueAtTime(0, audioCtx.currentTime + 2); }
Specifications
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'linearRampToValueAtTime' in that specification. |
Working Draft |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|---|
Basic support | 14 webkit | (Yes) | 23 | No support | 15 webkit 22 (unprefixed) |
6 webkit |
Unprefixed | (Yes) | (Yes) |
Feature | Android | Chrome | Edge | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|---|---|
Basic support | No support | (Yes) | (Yes) | 25 | 1.2 | No support | No support | 6 webkit | 28 webkit |
Unprefixed | (Yes) | (Yes) | (Yes) | (Yes) |