AudioWorkletGlobalScope

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AudioWorkletGlobalScope 接口在 Web 音频 API represents a global execution context for user-supplied code, which defines custom AudioWorkletProcessor -derived classes. 每个 BaseAudioContext has a single AudioWorklet available under the audioWorklet property, which runs its code in a single AudioWorkletGlobalScope .

As the global execution context is shared across the current BaseAudioContext , it's possible to define any other variables and perform any actions allowed in worklets — apart from defining AudioWorkletProcessor -derived classes.

特性

currentFrame 只读
currentTime 只读: Returns a double that represents the ever-increasing context time of the audio block being processed. It is equal to the currentTime 特性为 BaseAudioContext the worklet belongs to.
sampleRate 只读: Returns a float that represents the sample rate of the associated BaseAudioContext .

方法

registerProcessor(): Registers a class derived from the AudioWorkletProcessor interface. The class can then be used by creating an AudioWorkletNode , providing its registered name.

范例

In this example we output all global properties into the console in the constructor of a custom AudioWorkletProcessor .

First we need to define the processor, and register it. Note that this should be done in a separate file.

// test-processor.js
class TestProcessor extends AudioWorkletProcessor {
  constructor () {
    super()
    // current sample-frame and time at the moment of instantiation
    // to see values change, you can put these two lines in process method
    console.log(currentFrame)
    console.log(currentTime)
  }
  // the process method is required - simply output silence,
  // which the outputs are already filled with
  process (inputs, outputs, parameters) {
    return true
  }
}
// the sample rate is not going to change ever,
// because it's a read-only property of a BaseAudioContext
// and is set only during its instantiation
console.log(sampleRate)
// you can declare any variables and use them in your processors
// for example it may be an ArrayBuffer with a wavetable
const usefulVariable = 42
console.log(usefulVariable)
registerProcessor('test-processor', TestProcessor)

Next, in our main scripts file we'll load the processor, create an instance of AudioWorkletNode — passing the name of the processor to it — and connect the node to an audio graph. We should see the output of console.log calls in the console:

const audioContext = new AudioContext()
await audioContext.audioWorklet.addModule('test-processor.js')
const testNode = new AudioWorkletNode(audioContext, 'test-processor')
testNode.connect(audioContext.destination)

规范

规范	状态	注释
Web 音频 API The definition of 'AudioWorkletGlobalScope' 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
`AudioWorkletGlobalScope`	Chrome 66	Edge 79	Firefox 76	IE 不支持 No	Opera 53	Safari 不支持 No	WebView Android 66	Chrome Android 66	Firefox Android 不支持 No	Opera Android 47	Safari iOS 不支持 No	Samsung Internet Android 9.0
`currentFrame`	Chrome 66	Edge 79	Firefox 76	IE 不支持 No	Opera 53	Safari 不支持 No	WebView Android 66	Chrome Android 66	Firefox Android 不支持 No	Opera Android 47	Safari iOS 不支持 No	Samsung Internet Android 9.0
`currentTime`	Chrome 66	Edge 79	Firefox 76	IE 不支持 No	Opera 53	Safari 不支持 No	WebView Android 66	Chrome Android 66	Firefox Android 不支持 No	Opera Android 47	Safari iOS 不支持 No	Samsung Internet Android 9.0
`registerProcessor`	Chrome 66	Edge 79	Firefox 76	IE 不支持 No	Opera 53	Safari 不支持 No	WebView Android 66	Chrome Android 66	Firefox Android 不支持 No	Opera Android 47	Safari iOS 不支持 No	Samsung Internet Android 9.0
`sampleRate`	Chrome 66	Edge 79	Firefox 76	IE 不支持 No	Opera 53	Safari 不支持 No	WebView Android 66	Chrome Android 66	Firefox Android 不支持 No	Opera Android 47	Safari iOS 不支持 No	Samsung Internet Android 9.0

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