GainNode

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 接口。

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"

构造函数

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

特性

Inherits properties from its parent, AudioNode .

GainNode.gain 只读
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.

方法

No specific method; inherits methods from its parent, AudioNode .

范例

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 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 == "") {
    // 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.innerHTML = "Unmute";
  } else {
    gainNode.gain.setValueAtTime(1, audioCtx.currentTime);
    mute.id = "";
    mute.innerHTML = "Mute";
  }
}
					

规范

规范 状态 Comment
Web 音频 API
The definition of 'GainNode' in that specification.
工作草案

浏览器兼容性

更新 GitHub 上的兼容性数据
Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
GainNode Chrome 14 Edge ≤18 Firefox 25 IE 不支持 No Opera 15 Safari 6 WebView Android Yes Chrome Android 18 Firefox Android 26 Opera Android 14 Safari iOS Yes Samsung Internet Android 1.0
GainNode() 构造函数 Chrome 55
注意事项
55
注意事项
Before Chrome 59, the default values were not supported.
Edge ≤79 Firefox 53 IE 不支持 No Opera 42 Safari ? WebView Android 55
注意事项
55
注意事项
Before Chrome 59, the default values were not supported.
Chrome Android 55
注意事项
55
注意事项
Before Chrome 59, the default values were not supported.
Firefox Android 53 Opera Android 42 Safari iOS ? Samsung Internet Android 6.0
注意事项
6.0
注意事项
Before Samsung Internet 7.0, the default values were not supported.
gain Chrome 14 Edge 12 Firefox 25 IE 不支持 No Opera 15 Safari 6 WebView Android Yes Chrome Android 18 Firefox Android 26 Opera Android 14 Safari iOS Yes Samsung Internet Android 1.0

图例

完整支持
完整支持
不支持
不支持
兼容性未知
兼容性未知
见实现注意事项。

另请参阅