AudioParam.linearRampToValueAtTime()
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 undefined
.
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 |
---|
Web Audio API # dom-audioparam-linearramptovalueattime |
Browser compatibility
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