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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 instantly applied, causing unaesthetic 'clicks' in the resulting audio. To prevent this from happening, never change the value directly but use the exponential interpolation methods on the AudioParam interface.

The GainNode is increasing the gain of the output.

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 a GainNode object. You shouldn't manually create a gain node; instead, use the method AudioContext.createGain().

Properties

Inherits properties from its parent, AudioNode.

GainNode.gain Read only
Is an a-rate AudioParam representing the amount of gain to apply. You have to set AudioParam.value or use the methods of AudioParam to change the effect of gain.

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  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support14 Yes25 No156
GainNode() constructor551 ?53 No42 ?
gain14 Yes25 No156
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support1414 Yes26 No15 ?
GainNode() constructor551551 ?53 No42 ?
gain Yes14 Yes26 No15 ?

1. Before Chrome 59, the default values were not supported.

See also

ドキュメントのタグと貢献者

 最終更新者: Jedipedia,