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GainNode 介面代表的是音量改變。 這是 AudioNode 音訊處理模組,可以對輸入的訊號做增益 (gain) 後輸出。一個 GainNode 有一個輸入和一個輸出,兩者有相同的聲道數。

增益 (gain) 是無單位的數值,隨時間變化,會用來和所有輸入聲道的取樣做相乘。 如果更改的話,新的增益會用 de-zippering 演算法處理,以避免輸出聲音出現難聽的「喀」聲。

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 an GainNode object.

Properties

Inherits properties from its parent, AudioNode.

GainNode.gain Read only
a-rate AudioParam ,代表增益值

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.getUserMedia) {
 navigator.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 ? ? ? 42 ?
Feature Android Android Webview Edge Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support (Yes) (Yes) 26.0 1.2 ? (Yes) ? 33.0
constructor No support 55.0 ? ? ? ? 42 ? 55.0

See also

文件標籤與貢獻者

 此頁面的貢獻者: stdio2017
 最近更新: stdio2017,