Syntax
js
exponentialRampToValueAtTime(value, endTime)
Parameters
Return value
A reference to this AudioParam object. In some browsers older
implementations of this interface return undefined.
Examples
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, 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:
js
// create audio context
const audioCtx = new AudioContext();
// set basic variables for example
const myAudio = document.querySelector("audio");
const expRampPlus = document.querySelector(".exp-ramp-plus");
const expRampMinus = document.querySelector(".exp-ramp-minus");
// Create a MediaElementAudioSourceNode
// Feed the HTMLMediaElement into it
const source = audioCtx.createMediaElementSource(myAudio);
// Create a gain node and set its gain value to 0.5
const 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 = () => {
gainNode.gain.exponentialRampToValueAtTime(1.0, audioCtx.currentTime + 2);
};
expRampMinus.onclick = () => {
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 |
|---|
| Web Audio API # dom-audioparam-exponentialramptovalueattime |