The GainNode interface represents a change in volume. It is an AudioNode audio-processing module that causes a given gain to be applied to the input data before its propagation to the output. A GainNode always has exactly one input and one output, both with the same number of channels.
The gain is a unitless value, changing with time, that is multiplied to each corresponding sample of all input channels. If modified, the new gain is applied using a de-zippering algorithm in order to prevent unaesthetic 'clicks' from appearing in the resulting audio.
| Number of inputs | 1 |
|---|---|
| Number of outputs | 1 |
| Channel count mode | "max" |
| Channel count | 2 (not used in the default count mode) |
| Channel interpretation | "speakers" |
Constructor
GainNode()- Creates a new instance of an
GainNodeobject. You shouldn't manually create a gain node; instead, use the methodAudioContext.createGain().
Properties
Inherits properties from its parent, AudioNode.
GainNode.gainRead only- Is an a-rate
AudioParamrepresenting the amount of gain to apply.
Methods
No specific method; inherits methods from its parent, AudioNode.
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> <a class="mute">Mute button</a> </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 occured: ' + 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 == "") {
gainNode.gain.value = 0;
mute.id = "activated";
mute.innerHTML = "Unmute";
} else {
gainNode.gain.value = 1;
mute.id = "";
mute.innerHTML = "Mute";
}
}
Specifications
| Specification | Status | Comment |
|---|---|---|
| Web Audio API The definition of 'GainNode' in that specification. |
Working Draft |