GainNode | Web API

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构造函数
特性
方法
范例
规范
浏览器兼容性
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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.

输入数	`1`
输出数	`1`
通道计数模式	`"max"`
通道计数	`2` (不用于默认计数模式)
通道解释	`"speakers"`

构造函数

GainNode(): 创建新的实例化 GainNode object. You shouldn't manually create a gain node; instead, use the method AudioContext.createGain() .

特性

继承的特性来自其父级， AudioNode .

GainNode.gain 只读: 是 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	注释
Web 音频 API The definition of 'GainNode' in that specification.	工作草案

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	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	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
不支持
兼容性未知 ?

另请参阅

使用 Web 音频 API

元数据

最后修改： Jan 25, 2020

在此页

构造函数

特性

方法

范例

规范

浏览器兼容性

图例

另请参阅

相关话题