--- title: AudioWorkletProcessor slug: Web/API/AudioWorkletProcessor translation_of: Web/API/AudioWorkletProcessor ---

{{APIRef("Web Audio API")}}

Web Audio API的 AudioWorkletProcessor 接口代表了一个 自定义的音频处理代码 {{domxref("AudioWorkletNode")}}. 它身处于 {{domxref("AudioWorkletGlobalScope")}} 并运行在 Web Audio rendering 线程上. 同时, 一个建立在其基础上的 {{domxref("AudioWorkletNode")}} 运行在主线程上.

构造函数

AudioWorkletProcessor 及其子类不能通过用户提供的的代码直接实例化。它们只能随着与之相联系{{domxref("AudioWorkletNode")}}s的创建而被其创建再内部。其子类的构造函数将被一个可选对象调用，因此您可以执行自定义的初始化过程——详细信息请参见构造函数页面。
{{domxref("AudioWorkletProcessor.AudioWorkletProcessor", "AudioWorkletProcessor()")}}
创建一个 AudioWorkletProcessor 对象的新实例。

属性

{{domxref("AudioWorkletProcessor.port", "port")}} {{readonlyinline}}
返回一个用于在处理程序和其所属的{{domxref("AudioWorkletNode")}}间双向通信的 {{domxref("MessagePort")}} 。 另一端 可通过该节点的{{domxref("AudioWorkletNode.port", "port")}} 属性使用.

方法

AudioWorkletProcessor 接口没有定义任何自己的方法。但是, 您必须提供一个 {{domxref("AudioWorkletProcessor.process", "process()")}} 方法, 用以处理音频流。

事件

AudioWorkletProcessor 接口不响应任何事件。

使用说明

Deriving classes

要自定义音频处理代码， 你必须从AudioWorkletProcessor 接口派生一个类. 这个派生类必须具有在该接口中不曾定义的{{domxref("AudioWorkletProcessor.process", "process")}} 方法. 该方法将被每个含有128 样本帧的块调用并且接受输入和输出数组以及自定义的{{domxref("AudioParam")}}s (如果它们刚被定义了) 的计算值作为参数. 您可以使用输入和 音频参数值去填充输出数组, 这是默认的用于使输出静音。

Optionally, if you want custom {{domxref("AudioParam")}}s on your node, you can supply a {{domxref("AudioWorkletProcessor.parameterDescriptors", "parameterDescriptors")}} property as a static getter on the processor. The array of {{domxref("AudioParamDescriptor")}}-based objects returned is used internally to create the {{domxref("AudioParam")}}s during the instantiation of the AudioWorkletNode.

The resulting AudioParams reside in the {{domxref("AudioWorkletNode.parameters", "parameters")}} property of the node and can be automated using standard methods such as linearRampToValueAtTime. Their calculated values will be passed into the {{domxref("AudioWorkletProcessor.process", "process()")}} method of the processor for you to shape the node output accordingly.

处理音频

一个创建自定义音频处理算法的步骤的实例：

  1. 创建一个独立的文件;
  2. 在这个文件中:
    1. Extend the AudioWorkletProcessor class (see "Deriving classes" section) and supply your own {{domxref("AudioWorkletProcessor.process", "process()")}} method in it;
    2. Register the processor using {{domxref("AudioWorkletGlobalScope.registerProcessor()")}} method;
  3. Load the file using {{domxref("Worklet.addModule", "addModule()")}} method on your audio context's {{domxref("BaseAudioContext.audioWorklet", "audioWorklet")}} property;
  4. Create an {{domxref("AudioWorkletNode")}} based on the processor. The processor will be instantiated internally by the AudioWorkletNode constructor.
  5. Connect the node to the other nodes.

例子

In the example below we create a custom {{domxref("AudioWorkletNode")}} that outputs white noise.

First, we need to define a custom AudioWorkletProcessor, which will output white noise, and register it. Note that this should be done in a separate file.

// white-noise-processor.js
class WhiteNoiseProcessor extends AudioWorkletProcessor {
  process (inputs, outputs, parameters) {
    const output = outputs[0]
    output.forEach(channel => {
      for (let i = 0; i < channel.length; i++) {
        channel[i] = Math.random() * 2 - 1
      }
    })
    return true
  }
}

registerProcessor('white-noise-processor', WhiteNoiseProcessor)

Next, in our main script file we'll load the processor, create an instance of {{domxref("AudioWorkletNode")}}, passing it the name of the processor, then connect the node to an audio graph.

const audioContext = new AudioContext()
await audioContext.audioWorklet.addModule('white-noise-processor.js')
const whiteNoiseNode = new AudioWorkletNode(audioContext, 'white-noise-processor')
whiteNoiseNode.connect(audioContext.destination)

Specifications

Specification Status Comment
{{SpecName('Web Audio API', '#audioworkletprocessor', 'AudioWorkletProcessor')}} {{Spec2('Web Audio API')}}

Browser compatibility

{{Compat("api.AudioWorkletProcessor")}}

See also