Questa traduzione è incompleta. Collabora alla traduzione di questo articolo dall’originale in lingua inglese.

L'interfaccia GainNode  rappresenta un cambio di volume, un operazione fondamentale nelle applicazioni audio. E' un modulo di elaborazione audio che fa si che venga applicato un guadagno ai dati in ingresso prima che siano propagati verso l'uscita. Un GainNode ha esattamente un ingresso (input) e una sola uscita (output), entrambi con lo stesso numero di canali.

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.

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.

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

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 10.0webkit (Yes) 25.0 (25.0)  No support 15webkit
22
6.0webkit
constructor 55.0 (Yes) 53 (53) ? 42 ?
Feature Android Android Webview Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support (Yes) (Yes) 26.0 ? (Yes) ? 33.0
constructor No support 55.0 (Yes) 53.0 (53) ? 42 ? 55.0

See also

Tag del documento e collaboratori

 Hanno collaborato alla realizzazione di questa pagina: ExplosiveLab
 Ultima modifica di: ExplosiveLab,