AudioParam.setValueAtTime()

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规范
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setValueAtTime() 方法在 AudioParam interface schedules an instant change to the AudioParam value at a precise time, as measured against AudioContext.currentTime . The new value is given in the value parameter.

句法

var AudioParam = AudioParam.setValueAtTime(value, startTime)

参数

值
startTime: A double representing the time (in seconds) after the AudioContext was first created that the change in value will happen. A TypeError is thrown if this value is negative.

A reference to this AudioParam object. In some browsers older implementations of this interface return void.

范例

This simple example features a media element source with two control buttons (see our webaudio-examples repo for the source code, or view the example live ). When the buttons are pressed, the currGain variable is incremented/decremented by 0.25, then the setValueAtTime() method is used to set the gain value equal to currGain , one second from now ( audioCtx.currentTime + 1 )。

// create audio context
var AudioContext = window.AudioContext || window.webkitAudioContext;
var audioCtx = new AudioContext();
// set basic variables for example
var myAudio = document.querySelector('audio');
var pre = document.querySelector('pre');
var myScript = document.querySelector('script');
pre.innerHTML = myScript.innerHTML;
var targetAtTimePlus = document.querySelector('.set-target-at-time-plus');
var targetAtTimeMinus = document.querySelector('.set-target-at-time-minus');
// Create a MediaElementAudioSourceNode
// Feed the HTMLMediaElement into it
var source = audioCtx.createMediaElementSource(myAudio);
// Create a gain node and set it's gain value to 0.5
var gainNode = audioCtx.createGain();
gainNode.gain.value = 0.5;
var currGain = gainNode.gain.value;
// connect the AudioBufferSourceNode to the gainNode
// and the gainNode to the destination
source.connect(gainNode);
gainNode.connect(audioCtx.destination);
// set buttons to do something onclick
targetAtTimePlus.onclick = function() {
  currGain += 0.25;
  gainNode.gain.setValueAtTime(currGain, audioCtx.currentTime + 1);
}
targetAtTimeMinus.onclick = function() {
  currGain -= 0.25;
  gainNode.gain.setValueAtTime(currGain, audioCtx.currentTime + 1);
}

规范

规范	状态	注释
Web 音频 API The definition of 'setValueAtTime' 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
`setValueAtTime`	Chrome 14	Edge 12	Firefox 25	IE 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

另请参阅

使用 Web 音频 API

元数据

最后修改： 2019 年 3 月 23 日

Web 音频 API
AudioParam
特性
方法
1. cancelAndHoldAtTime()
2. cancelScheduledValues()
3. exponentialRampToValueAtTime()
4. linearRampToValueAtTime()
5. setTargetAtTime()
6. setValueAtTime()
7. setValueCurveAtTime()
Related pages for Web Audio API

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句法

参数

返回

范例

规范

浏览器兼容性

图例

另请参阅

相关话题