OfflineAudioContext

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OfflineAudioContext interface is an AudioContext interface representing an audio-processing graph built from linked together AudioNode s. In contrast with a standard AudioContext ， OfflineAudioContext doesn't render the audio to the device hardware; instead, it generates it, as fast as it can, and outputs the result to an AudioBuffer .

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构造函数

OfflineAudioContext.OfflineAudioContext(): 创建新的 OfflineAudioContext 实例。

特性

Also inherits properties from its parent interface, BaseAudioContext .

OfflineAudioContext.length 只读

事件处理程序

OfflineAudioContext.oncomplete: 是 EventHandler called when processing is terminated, that is when the complete event (of type OfflineAudioCompletionEvent ) is raised, after the event-based version of OfflineAudioContext.startRendering() 被使用。

方法

Also inherits methods from its parent interface, BaseAudioContext .

OfflineAudioContext.suspend()
OfflineAudioContext.startRendering()

弃用方法

OfflineAudioContext.resume()

注意： resume() method is still available — it is now defined on the BaseAudioContext interface (see BaseAudioContext.resume() ) and thus can be accessed by both the AudioContext and OfflineAudioContext 接口。

事件

监听这些事件使用 addEventListener() 或通过把事件监听器赋值给 on eventname property of this interface:

complete: Fired when the rendering of an offline audio context is complete.
Also available using the oncomplete event handler property.

范例

In this simple example, we declare both an AudioContext 和 OfflineAudioContext object. We use the AudioContext to load an audio track via XHR ( AudioContext.decodeAudioData ), then the OfflineAudioContext to render the audio into an AudioBufferSourceNode and play the track through. After the offline audio graph is set up, you need to render it to an AudioBuffer 使用 OfflineAudioContext.startRendering .

当 startRendering() promise resolves, rendering has completed and the output AudioBuffer is returned out of the promise.

At this point we create another audio context, create an AudioBufferSourceNode inside it, and set its buffer to be equal to the promise AudioBuffer . This is then played as part of a simple standard audio graph.

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

// define online and offline audio context
var audioCtx = new AudioContext();
var offlineCtx = new OfflineAudioContext(2,44100*40,44100);
source = offlineCtx.createBufferSource();
// use XHR to load an audio track, and
// decodeAudioData to decode it and OfflineAudioContext to render it
function getData() {
  request = new XMLHttpRequest();
  request.open('GET', 'viper.ogg', true);
  request.responseType = 'arraybuffer';
  request.onload = function() {
    var audioData = request.response;
    audioCtx.decodeAudioData(audioData, function(buffer) {
      myBuffer = buffer;
      source.buffer = myBuffer;
      source.connect(offlineCtx.destination);
      source.start();
      //source.loop = true;
      offlineCtx.startRendering().then(function(renderedBuffer) {
        console.log('Rendering completed successfully');
        var song = audioCtx.createBufferSource();
        song.buffer = renderedBuffer;
        song.connect(audioCtx.destination);
        play.onclick = function() {
          song.start();
        }
      }).catch(function(err) {
          console.log('Rendering failed: ' + err);
          // Note: The promise should reject when startRendering is called a second time on an OfflineAudioContext
      });
    });
  }
  request.send();
}
// Run getData to start the process off
getData();

规范

规范	状态	注释
Web 音频 API The definition of 'OfflineAudioContext' in that specification.	工作草案	初始定义

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`	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 ?	Samsung Internet Android 1.0
`OfflineAudioContext()` 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 version 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.
`complete` event	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 ?	Samsung Internet Android 1.0
`length`	Chrome 51	Edge 14	Firefox Yes	IE 不支持 No	Opera 38	Safari 不支持 No	WebView Android 51	Chrome Android 51	Firefox Android Yes	Opera Android 41	Safari iOS 不支持 No	Samsung Internet Android 5.0
`oncomplete`	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 ?	Samsung Internet Android 1.0
`resume`	Chrome 49	Edge ≤18	Firefox 不支持 No	IE 不支持 No	Opera 36	Safari 不支持 No	WebView Android 49	Chrome Android 49	Firefox Android 不支持 No	Opera Android 36	Safari iOS 不支持 No	Samsung Internet Android 5.0
`startRendering`	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 ?	Samsung Internet Android 1.0
`suspend`	Chrome 49	Edge ≤18	Firefox 不支持 No	IE 不支持 No	Opera 36	Safari 不支持 No	WebView Android 49	Chrome Android 49	Firefox Android 不支持 No	Opera Android 36	Safari iOS 不支持 No	Samsung Internet Android 5.0

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： Apr 17, 2019

在此页

构造函数

特性

事件处理程序

方法

弃用方法

事件

范例

规范

浏览器兼容性

图例

另请参阅

相关话题