OfflineAudioContext.OfflineAudioContext()

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OfflineAudioContext() constructor—part of the Web 音频 API —creates and returns a new OfflineAudioContext object instance, which can then be used to render audio to an AudioBuffer rather than to an audio output device.

句法

var offlineAudioCtx = new OfflineAudioContext(numberOfChannels, length, sampleRate);
var offlineAudioCtx = new OfflineAudioContext(options);

参数

You can specify the parameters for the OfflineAudioContext() constructor as either the same set of parameters as are inputs into the AudioContext.createBuffer() method, or by passing those parameters in an 选项 object. Either way, the individual parameters are the same.

numberOfChannels: An integer specifying the number of channels the resulting AudioBuffer should have.
length: An integer specifying the size of the buffer to create for the audio context, in sample-frames, where one sample-frame is a unit that can contain a single sample of audio data for every channel in the audio data. For example, a 5-second buffer with a sampleRate of 48000Hz would have a length of 5 * 48000 = 240000 sample-frames.
sampleRate

It is important to note that, whereas you can create a new AudioContext 使用 new AudioContext() constructor with no arguments, the OfflineAudioContext() constructor requires three arguments, since it needs to create an AudioBuffer . This works in exactly the same way as when you create a new AudioBuffer 采用 AudioContext.createBuffer() method. For more detail, read Audio buffers: frames, samples and channels from our 基本概念 guide.

返回值

新的 OfflineAudioContext object whose associated AudioBuffer is configured as requested.

Like a regular AudioContext ， OfflineAudioContext can be the target of events, therefore it implements the EventTarget 接口。

范例

const offlineCtx = new OfflineAudioContext({
  numberOfChannels: 2,
  length: 44100 * 40,
  sampleRate: 44100,
});
const source = offlineCtx.createBufferSource();
// etc...

For a full working example, see our offline-audio-context-promise Github repo (see the 源代码 too.)

规范

规范	状态	注释
Web 音频 API The definition of 'OfflineAudioContext()' 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
`OfflineAudioContext()` 构造函数	Chrome 55 55 Before Chrome 59, the default values were not supported.	Edge ≤79	Firefox 53	IE No	Opera 42	Safari ?	WebView Android 55 55 Before version 59, the default values were not supported.	Chrome Android 55 55 Before Chrome 59, the default values were not supported.	Firefox Android 53	Opera Android 42	Safari iOS ?	Samsung Internet Android 6.0 6.0 Before Samsung Internet 7.0, the default values were not supported.
Parameters accepted as a single object, as well as being passed in individually	Chrome 62	Edge ≤79	Firefox 57	IE No	Opera 49	Safari No	WebView Android 62	Chrome Android 62	Firefox Android 57	Opera Android 46	Safari iOS No	Samsung Internet Android 8.0

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最后修改： Jun 13, 2019

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句法

参数

返回值

范例

规范

浏览器兼容性

图例

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