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---
title: AudioContext.decodeAudioData()
slug: Web/API/BaseAudioContext/decodeAudioData
tags:
- API
- Audio
- audio接口
- 音频解码
translation_of: Web/API/BaseAudioContext/decodeAudioData
original_slug: Web/API/AudioContext/decodeAudioData
---
<p>{{ APIRef("Web Audio API") }}</p>
<div>
<p>{{ domxref("AudioContext") }}接口的<code>decodeAudioData()方法可用于异步解码</code>音频文件中的 {{domxref("ArrayBuffer")}}. <code>ArrayBuffer数据可以通过</code>{{domxref("XMLHttpRequest")}}和{{domxref("FileReader")}}来获取. AudioBuffer是通过AudioContext采样率进行解码的,然后通过回调返回结果.</p>
</div>
<p>这是从音频轨道创建用于web audio API音频源的首选方法。</p>
<h2 id="语法">语法</h2>
<p>旧版的回调函数语法</p>
<pre class="syntaxbox">audioCtx.decodeAudioData(audioData, function(decodedData) {
// use the decoded data here
});</pre>
<p>新版的promise-based语法:</p>
<pre class="syntaxbox">audioCtx.decodeAudioData(audioData).then(function(decodedData) {
// use the decoded data here
});</pre>
<h2 id="举例">举例</h2>
<p>在本章节中，我们将首先学习基于回调的系统，然后采用新的基于promise-based的语法</p>
<h3 id="旧的回调语法">旧的回调语法</h3>
<p>在这个事例中, <code>getData()</code> 方法使用XHR加载一个音轨,设置请求的responsetype为ArrayBuffer使它返回一个arraybuffer数据，然后存储在audioData变量中. 然后我们将这个arraybuffer数据置于<code>decodeAudioData()方法中使用，当成功解码PCM Data后通过回调返回</code>, 将返回的结果通过{{ domxref("AudioContext.createBufferSource()") }}接口进行处理并获得一个{{ domxref("AudioBufferSourceNode") }}, 将源连接至{{domxref("AudioContext.destination") }}并将它设置为循环的.</p>
<p>通过按钮来运行 <code>getData()</code> 来获取音轨并播放它. 当使用 <code>stop()</code> 方法后source将会被清除.</p>
<div class="note">
<p><strong>Note</strong>: You can <a href="http://mdn.github.io/decode-audio-data/">run the example live</a> (or <a href="https://github.com/mdn/decode-audio-data">view the source</a>.)</p>
</div>
<pre class="brush: js">// define variables
var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var source;
var pre = document.querySelector('pre');
var myScript = document.querySelector('script');
var play = document.querySelector('.play');
var stop = document.querySelector('.stop');
// use XHR to load an audio track, and
// decodeAudioData to decode it and stick it in a buffer.
// Then we put the buffer into the source
function getData() {
source = audioCtx.createBufferSource();
var request = new XMLHttpRequest();
request.open('GET', 'viper.ogg', true);
request.responseType = 'arraybuffer';
request.onload = function() {
var audioData = request.response;
audioCtx.decodeAudioData(audioData, function(buffer) {
source.buffer = buffer;
source.connect(audioCtx.destination);
source.loop = true;
},
function(e){"Error with decoding audio data" + e.err});
}
request.send();
}
// wire up buttons to stop and play audio
play.onclick = function() {
getData();
source.start(0);
play.setAttribute('disabled', 'disabled');
}
stop.onclick = function() {
source.stop(0);
play.removeAttribute('disabled');
}
// dump script to pre element
pre.innerHTML = myScript.innerHTML;</pre>
<h3 id="新的promise-based语法">新的promise-based语法</h3>
<pre class="brush: js">ctx.decodeAudioData(compressedBuffer).then(function(decodedData) {
// use the decoded data here
});</pre>
<h2 id="参数">参数</h2>
<dl>
<dt>ArrayBuffer</dt>
<dd>将会被解码的音频数据，可通过{{domxref("XMLHttpRequest")}}或{{domxref("FileReader")}}来获取.</dd>
<dt>DecodeSuccessCallback</dt>
<dd>当成功解码后会被调用的回调函数. 该回调函数只有一个AudioBuffer类型参数.</dd>
<dt>DecodeErrorCallback</dt>
<dd>一个可选的错误回调函数.</dd>
</dl>
<h2 id="返回">返回</h2>
<p>一个 {{domxref("Promise") }}对象.</p>
<h2 id="标准">标准</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>{{SpecName('Web Audio API', '#widl-AudioContext-decodeAudioData-Promise-AudioBuffer--ArrayBuffer-audioData-DecodeSuccessCallback-successCallback-DecodeErrorCallback-errorCallback', 'decodeAudioData()')}}</td>
<td>{{Spec2('Web Audio API')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="浏览器支持">浏览器支持</h2>
{{Compat("api.BaseAudioContext.decodeAudioData")}}
<h2 id="See_also">See also</h2>
<ul>
<li><a href="/en-US/docs/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
</ul>
|
