---
title: AnalyserNode.getByteTimeDomainData()
slug: Web/API/AnalyserNode/getByteTimeDomainData
translation_of: Web/API/AnalyserNode/getByteTimeDomainData
---
<p>{{ APIRef("Mountain View APIRef Project") }}</p>

<p>{{ domxref("AnalyserNode") }} 接口的 <strong><code>getByteTimeDomainData()</code></strong> 方法复制当前波形或时域数据到传递给它的  {{domxref("Uint8Array")}} (无符号字节数组) 中。</p>

<p>如果该数组的元素少于 {{domxref("AnalyserNode.fftSize")}}, 多余的元素会被丢弃。如果它有多于所需的元素，则忽略多余的元素。</p>

<h2 id="语法">语法</h2>

<pre class="brush: js">var audioCtx = new AudioContext();
var analyser = audioCtx.createAnalyser();
var dataArray = new Uint8Array(analyser.fftSize); // Uint8Array should be the same length as the fftSize
analyser.getByteTimeDomainData(dataArray); // fill the Uint8Array with data returned from getByteTimeDomainData()
</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>array</code></dt>
 <dd>时域数据将被复制到的 {{domxref("Uint8Array")}} 。<br>
 如果数组中的元素少于 {{domxref("AnalyserNode.frequencyBinCount")}}, 则会删除多余的元素。如果它包含的元素多于需要的元素，则忽略多余的元素。</dd>
</dl>

<h3 id="返回值">返回值</h3>

<p><strong><code>void</code></strong> | None</p>

<h2 id="例子">例子</h2>

<p>以下的例子展示了 {{domxref("AudioContext")}} 生成一个 <code>AnalyserNode</code> 基础用法， 然后通过 {{domxref("window.requestAnimationFrame()","requestAnimationFrame")}} 和 {{htmlelement("canvas")}} 重复的收集和绘制一个当前音频输入的“示波器样式”输出。 有关更完整的应用实例/信息，请查看我们的 <a href="https://mdn.github.io/voice-change-o-matic/">Voice-change-O-matic</a> demo (有关代码请参阅 <a href="https://github.com/mdn/voice-change-o-matic/blob/gh-pages/scripts/app.js#L128-L205">app.js lines 128–205</a>)。</p>

<pre class="brush: js">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var analyser = audioCtx.createAnalyser();

  ...

analyser.fftSize = 2048;
var bufferLength = analyser.frequencyBinCount;
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)';

      var sliceWidth = WIDTH * 1.0 / bufferLength;
      var x = 0;

      ctx.beginPath();
      for(var i = 0; i &lt; bufferLength; i++) {
        let v = dataArray[i]/128.0,
            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="规格">规格</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-AnalyserNode-getByteTimeDomainData-void-Uint8Array-array', 'getByteTimeDomainData()')}}</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>

<div>


<p>{{Compat("api.AnalyserNode.getByteTimeDomainData")}}</p>
</div>

<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>