BaseAudioContext.createGain()
The createGain()
method of the BaseAudioContext
interface creates a GainNode
, which can be used to control the
overall gain (or volume) of the audio graph.
Note: The GainNode()
constructor is the recommended way to create a GainNode
; see
Creating an AudioNode.
Syntax
var gainNode = AudioContext.createGain();
Return value
A GainNode
which takes as input one or more audio sources and outputs
audio whose volume has been adjusted in gain (volume) to a level specified by the node's
GainNode.gain
a-rate
parameter.
Example
The following example shows basic usage of an AudioContext
to create a
GainNode
, which is then used to mute and unmute the audio when a Mute
button is clicked by changing the gain
property value.
The below snippet wouldn't work as is — for a complete working example, check out our Voice-change-O-matic demo (view source.)
<div>
<button class="mute">Mute button</button>
</div>
var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var gainNode = audioCtx.createGain();
var mute = document.querySelector('.mute');
var source;
if (navigator.mediaDevices.getUserMedia) {
navigator.mediaDevices.getUserMedia (
// constraints - only audio needed for this app
{
audio: true
},
// Success callback
function(stream) {
source = audioCtx.createMediaStreamSource(stream);
},
// Error callback
function(err) {
console.log('The following gUM error occurred: ' + err);
}
);
} else {
console.log('getUserMedia not supported on your browser!');
}
source.connect(gainNode);
gainNode.connect(audioCtx.destination);
...
mute.onclick = voiceMute;
function voiceMute() {
if(mute.id == "") {
// 0 means mute. If you still hear something, make sure you haven't
// connected your source into the output in addition to using the GainNode.
gainNode.gain.setValueAtTime(0, audioCtx.currentTime);
mute.id = "activated";
mute.textContent = "Unmute";
} else {
gainNode.gain.setValueAtTime(1, audioCtx.currentTime);
mute.id = "";
mute.textContent = "Mute";
}
}
Specifications
Specification |
---|
Web Audio API # dom-baseaudiocontext-creategain |
Browser compatibility
BCD tables only load in the browser