Syntax
js
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
AudioContextwas first created that the change in value will happen. If the time is less thanAudioContext.currentTime, the change happens immediately. ATypeErroris thrown if this value is negative.
Return value
A reference to this AudioParam object. In some browsers older
implementations of this interface return undefined.
Examples
This simple example features a media element source with two control buttons (see our
webaudio-examples 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.)
js
// create audio context
const audioCtx = new AudioContext();
// set basic variables for example
const myAudio = document.querySelector("audio");
const pre = document.querySelector("pre");
const myScript = document.querySelector("script");
pre.textContent = myScript.textContent;
const targetAtTimePlus = document.querySelector(".set-target-at-time-plus");
const targetAtTimeMinus = document.querySelector(".set-target-at-time-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();
gainNode.gain.value = 0.5;
let 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 = () => {
currGain += 0.25;
gainNode.gain.setValueAtTime(currGain, audioCtx.currentTime + 1);
};
targetAtTimeMinus.onclick = () => {
currGain -= 0.25;
gainNode.gain.setValueAtTime(currGain, audioCtx.currentTime + 1);
};
Specifications
| Specification |
|---|
| Web Audio API # dom-audioparam-setvalueattime |