From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- .../analysernode/getbytefrequencydata/index.html | 151 +++++++++++++++++++++ 1 file changed, 151 insertions(+) create mode 100644 files/zh-cn/web/api/analysernode/getbytefrequencydata/index.html (limited to 'files/zh-cn/web/api/analysernode/getbytefrequencydata/index.html') 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 +--- +

{{ APIRef("Web Audio API") }}

+ +
+

{{ domxref("AnalyserNode") }}接口的getByteFrequencyData()方法将当前频率数据复制到传入的Uint8Array（无符号字节数组）中。

+ +

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.

+
+ +

语法

+ +
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
+
+ +

返回值

+ +

一个 {{domxref("Uint8Array")}}（无符号字节数组）.

+ +

例子

+ +

下面的例子展示了 {{domxref("AudioContext")}} 创建一个 AnalyserNode, 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).

+ +

更多的例子/信息, 查看 Voice-change-O-matic 演示 (相关代码在 app.js 的 128行~205行).

+ +
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 < 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();
+ +

参数

+ +
+
array (数组)
+
必须为{{domxref("Uint8Array")}}, 频域数据将复制到该数组内.
+
+ +

规范

+ + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('Web Audio API', '#widl-AnalyserNode-getByteFrequencyData-void-Uint8Array-array', 'getByteFrequencyData()')}}{{Spec2('Web Audio API')}} 
+ +

浏览器兼容性

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{{CompatibilityTable}}
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+ + + + + + + + + + + + + + + + + + + +
FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari (WebKit)
Basic support{{CompatChrome(10.0)}}{{property_prefix("webkit")}}{{CompatGeckoDesktop(25.0)}} {{CompatNo}}15.0{{property_prefix("webkit")}}
+ 22 (unprefixed)		6.0{{property_prefix("webkit")}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidFirefox Mobile (Gecko)Firefox OSIE MobileOpera MobileSafari MobileChrome for Android
Basic support{{CompatUnknown}}26.01.2{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}33.0
+
+ +

相关内容

+ + -- cgit v1.2.3-54-g00ecf