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---
title: AudioContext.createAnalyser()
slug: Web/API/BaseAudioContext/createAnalyser
translation_of: Web/API/BaseAudioContext/createAnalyser
original_slug: Web/API/AudioContext/createAnalyser
---
<p>{{ APIRef("Web Audio API") }}</p>
<div>
<p>{{ domxref("AudioContext") }}的<code>createAnalyser()</code>方法能创建一个{{ domxref("AnalyserNode") }}，可以用来获取音频时间和频率数据，以及实现数据可视化。</p>
</div>
<div class="note">
<p><strong>注意</strong>：关于该节点的更多信息，请查看{{domxref("AnalyserNode")}}</p>
</div>
<h2 id="语法">语法</h2>
<pre class="brush: js">var audioCtx = new AudioContext();
var analyser = audioCtx.createAnalyser();</pre>
<h3 id="Description" name="Description">返回值</h3>
<p>{{domxref("AnalyserNode")}}对象</p>
<h2 id="Examples" name="Examples">例子</h2>
<p>下面的例子展示了AudioContext创建分析器节点的基本用法，然后用requestAnimationFrame()来反复获取时域数据，并绘制出当前音频输入的“示波器风格”输出。更多完整例子请查看<a href="https://mdn.github.io/voice-change-o-matic/">Voice-change-O-matic</a> demo (中<a href="https://github.com/mdn/voice-change-o-matic/blob/gh-pages/scripts/app.js#L128-L205">app.js的128–205行</a>代码)</p>
<pre class="brush: js">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var analyser = audioCtx.createAnalyser();
...
analyser.fftSize = 2048;
var bufferLength = analyser.fftSize;
var dataArray = new Uint8Array(bufferLength);
analyser.getByteTimeDomainData(dataArray);
// draw an oscilloscope of the current audio source
function draw() {
drawVisual = requestAnimationFrame(draw);
analyser.getByteTimeDomainData(dataArray);
canvasCtx.fillStyle = 'rgb(200, 200, 200)';
canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
canvasCtx.lineWidth = 2;
canvasCtx.strokeStyle = 'rgb(0, 0, 0)';
canvasCtx.beginPath();
var sliceWidth = WIDTH * 1.0 / bufferLength;
var x = 0;
for(var i = 0; i < bufferLength; i++) {
var v = dataArray[i] / 128.0;
var y = v * HEIGHT/2;
if(i === 0) {
canvasCtx.moveTo(x, y);
} else {
canvasCtx.lineTo(x, y);
}
x += sliceWidth;
}
canvasCtx.lineTo(canvas.width, canvas.height/2);
canvasCtx.stroke();
};
draw();</pre>
<h2 id="规范">规范</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-createAnalyser-AnalyserNode', 'createAnalyser()')}}</td>
<td>{{Spec2('Web Audio API')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
{{Compat("api.BaseAudioContext.createAnalyser")}}
<h2 id="另见">另见</h2>
<ul>
<li><a href="/en-US/docs/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
</ul>
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