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: AudioBuffer.getChannelData()
+slug: Web/API/AudioBuffer/getChannelData
+translation_of: Web/API/AudioBuffer/getChannelData
+---
+<p>{{ APIRef("Web Audio API") }}</p>
+
+<p> {{ domxref("AudioBuffer") }} 接口的getChannelData()方法返回一{{domxref("Float32Array")}} ，其中包含与通道关联的PCM数据，通道参数定义(0表示第一个通道)。</p>
+
+<h2 id="语法">语法</h2>
+
+<pre class="brush: js;highlight[22]">var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);
+var nowBuffering = myArrayBuffer.getChannelData(channel);</pre>
+
+<h3 id="参数">参数</h3>
+
+<dl>
+ <dt>channel</dt>
+ <dd>channel属性是要获取特定通道数据的索引。0代表第一个通道。 如果索引值大于或等于{{domxref("AudioBuffer.numberOfChannels")}}, 会抛出一个索引大小异常（<code>INDEX_SIZE_ERR</code> ）的错误。</dd>
+</dl>
+
+<h3 id="返回值">返回值</h3>
+
+<p> {{domxref("Float32Array")}}.</p>
+
+<dl>
+</dl>
+
+<h2 id="例子">例子</h2>
+
+<p>在下例中，我们创建一个2秒钟的缓冲区，用白噪声填充它，然后通过{{domxref("AudioBufferSourceNode") }}来播放它. 评论应该会清楚的解释发生的事情。 你也可以<a href="https://mdn.github.io/webaudio-examples/audio-buffer/">实时运行代码</a>，或者<a href="https://github.com/mdn/webaudio-examples">查看源代码</a>。</p>
+
+<pre class="brush: js;highlight[21]">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
+var button = document.querySelector('button');
+var pre = document.querySelector('pre');
+var myScript = document.querySelector('script');
+
+pre.innerHTML = myScript.innerHTML;
+
+// Stereo
+var channels = 2;
+// Create an empty two second stereo buffer at the
+// sample rate of the AudioContext
+var frameCount = audioCtx.sampleRate * 2.0;
+
+var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);
+
+button.onclick = function() {
+  // Fill the buffer with white noise;
+  //just random values between -1.0 and 1.0
+  for (var channel = 0; channel &lt; channels; channel++) {
+   // This gives us the actual ArrayBuffer that contains the data
+   var nowBuffering = myArrayBuffer.getChannelData(channel);
+   for (var i = 0; i &lt; frameCount; i++) {
+     // Math.random() is in [0; 1.0]
+     // audio needs to be in [-1.0; 1.0]
+     nowBuffering[i] = Math.random() * 2 - 1;
+   }
+  }
+
+  // Get an AudioBufferSourceNode.
+  // This is the AudioNode to use when we want to play an AudioBuffer
+  var source = audioCtx.createBufferSource();
+  // set the buffer in the AudioBufferSourceNode
+  source.buffer = myArrayBuffer;
+  // connect the AudioBufferSourceNode to the
+  // destination so we can hear the sound
+  source.connect(audioCtx.destination);
+  // start the source playing
+  source.start();
+}</pre>
+
+<h2 id="Specification">Specification</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', '#dom-audiobuffer-getchanneldata', 'getChannelData')}}</td>
+   <td>{{Spec2('Web Audio API')}}</td>
+   <td> </td>
+  </tr>
+ </tbody>
+</table>
+
+<h2 id="Browser_compatibility">Browser compatibility</h2>
+
+<div>
+
+
+<p>{{Compat("api.AudioBuffer.getChannelData")}}</p>
+</div>
+
+<h2 id="See_also">See also</h2>
+
+<ul>
+ <li><a href="/en-US/docs/Web/API/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
+</ul>
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