initial commit

1 files changed, 151 insertions, 0 deletions

diff --git a/files/zh-cn/web/api/analysernode/getbytefrequencydata/index.html b/files/zh-cn/web/api/analysernode/getbytefrequencydata/index.html
new file mode 100644
index 0000000000..a16460525b
--- /dev/null
+++ b/files/zh-cn/web/api/analysernode/getbytefrequencydata/index.html
@@ -0,0 +1,151 @@
+---
+title: AnalyserNode.getByteFrequencyData()
+slug: Web/API/AnalyserNode/getByteFrequencyData
+translation_of: Web/API/AnalyserNode/getByteFrequencyData
+---
+<p>{{ APIRef("Web Audio API") }}</p>
+
+<div>
+<p>{{ domxref("AnalyserNode") }}接口的<strong><code>getByteFrequencyData()</code></strong>方法将当前频率数据复制到传入的Uint8Array（无符号字节数组）中。</p>
+
+<p>如果数组的长度小于 {{domxref("AnalyserNode.frequencyBinCount")}}, 那么Analyser多出的元素会被删除. 如果是大于, 那么数组多余的元素会被忽略.</p>
+</div>
+
+<h2 id="语法">语法</h2>
+
+<pre class="brush: js">var audioCtx = new AudioContext();
+var analyser = audioCtx.createAnalyser();
+var dataArray = new Uint8Array(analyser.frequencyBinCount); // Uint8Array 的长度应该和 frequencyBinCount 相等
+analyser.getByteFrequencyData(dataArray); // 调用 getByteFrequencyData 方法填充 Uint8Array
+</pre>
+
+<h3 id="返回值">返回值</h3>
+
+<p>一个 {{domxref("Uint8Array")}}（无符号字节数组）.</p>
+
+<h2 id="例子">例子</h2>
+
+<p>下面的例子展示了 {{domxref("AudioContext")}} 创建一个 <code>AnalyserNode</code>, 然后用 {{domxref("window.requestAnimationFrame()","requestAnimationFrame")}} 和 {{htmlelement("canvas")}} 去反复收集当前音频的频率数据, 并绘制为一个柱状风格的输出(频谱).</p>
+
+<p>更多的例子/信息, 查看 <a href="https://mdn.github.io/voice-change-o-matic/">Voice-change-O-matic</a> 演示 (相关代码在 <a href="https://github.com/mdn/voice-change-o-matic/blob/gh-pages/scripts/app.js#L128-L205">app.js 的 128行~205行</a>).</p>
+
+<pre class="brush: js">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
+var analyser = audioCtx.createAnalyser();
+
+  ...
+
+analyser.fftSize = 256;
+var bufferLength = analyser.frequencyBinCount;
+console.log(bufferLength);
+var dataArray = new Uint8Array(bufferLength);
+
+canvasCtx.clearRect(0, 0, WIDTH, HEIGHT);
+
+function draw() {
+  drawVisual = requestAnimationFrame(draw);
+
+  analyser.getByteFrequencyData(dataArray);
+
+  canvasCtx.fillStyle = 'rgb(0, 0, 0)';
+  canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
+
+  var barWidth = (WIDTH / bufferLength) * 2.5;
+  var barHeight;
+  var x = 0;
+
+  for(var i = 0; i &lt; bufferLength; i++) {
+    barHeight = dataArray[i];
+
+    canvasCtx.fillStyle = 'rgb(' + (barHeight+100) + ',50,50)';
+    canvasCtx.fillRect(x,HEIGHT-barHeight/2,barWidth,barHeight/2);
+
+    x += barWidth + 1;
+  }
+};
+
+draw();</pre>
+
+<h2 id="参数">参数</h2>
+
+<dl>
+ <dt>array (数组)</dt>
+ <dd>必须为{{domxref("Uint8Array")}}, 频域数据将复制到该数组内.</dd>
+</dl>
+
+<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-AnalyserNode-getByteFrequencyData-void-Uint8Array-array', 'getByteFrequencyData()')}}</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>{{CompatibilityTable}}</div>
+
+<div id="compat-desktop">
+<table class="compat-table">
+ <tbody>
+  <tr>
+   <th>Feature</th>
+   <th>Chrome</th>
+   <th>Firefox (Gecko)</th>
+   <th>Internet Explorer</th>
+   <th>Opera</th>
+   <th>Safari (WebKit)</th>
+  </tr>
+  <tr>
+   <td>Basic support</td>
+   <td>{{CompatChrome(10.0)}}{{property_prefix("webkit")}}</td>
+   <td>{{CompatGeckoDesktop(25.0)}} </td>
+   <td>{{CompatNo}}</td>
+   <td>15.0{{property_prefix("webkit")}}<br>
+    22 (unprefixed)</td>
+   <td>6.0{{property_prefix("webkit")}}</td>
+  </tr>
+ </tbody>
+</table>
+</div>
+
+<div id="compat-mobile">
+<table class="compat-table">
+ <tbody>
+  <tr>
+   <th>Feature</th>
+   <th>Android</th>
+   <th>Firefox Mobile (Gecko)</th>
+   <th>Firefox OS</th>
+   <th>IE Mobile</th>
+   <th>Opera Mobile</th>
+   <th>Safari Mobile</th>
+   <th>Chrome for Android</th>
+  </tr>
+  <tr>
+   <td>Basic support</td>
+   <td>{{CompatUnknown}}</td>
+   <td>26.0</td>
+   <td>1.2</td>
+   <td>{{CompatUnknown}}</td>
+   <td>{{CompatUnknown}}</td>
+   <td>{{CompatUnknown}}</td>
+   <td>33.0</td>
+  </tr>
+ </tbody>
+</table>
+</div>
+
+<h2 id="相关内容">相关内容</h2>
+
+<ul>
+ <li><a href="/en-US/docs/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
+</ul>