From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001
From: Peter Bengtsson <mail@peterbe.com>
Date: Tue, 8 Dec 2020 14:40:17 -0500
Subject: initial commit

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+---
+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>
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