AnalyserNode.getByteFrequencyData()

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getByteFrequencyData() 方法在 AnalyserNode interface copies the current frequency data into a Uint8Array (unsigned byte array) passed into it.

The frequency data is composed of integers on a scale from 0 to 255.

Each item in the array represents the decibel value for a specific frequency. The frequencies are spread linearly from 0 to 1/2 of the sample rate. For example, for 48000 sample rate, the last item of the array will represent the decibel value for 24000 Hz.

If the array has fewer elements than the AnalyserNode.frequencyBinCount , excess elements are dropped. If it has more elements than needed, excess elements are ignored.

句法

var audioCtx = new AudioContext();
var analyser = audioCtx.createAnalyser();
var dataArray = new Uint8Array(analyser.frequencyBinCount); // Uint8Array should be the same length as the frequencyBinCount
void analyser.getByteFrequencyData(dataArray); // fill the Uint8Array with data returned from getByteFrequencyData()

参数

array: Uint8Array that the frequency domain data will be copied to. For any sample which is silent, the value is - Infinity .
If the array has fewer elements than the AnalyserNode.frequencyBinCount , excess elements are dropped. If it has more elements than needed, excess elements are ignored.

返回值

None.

范例

The following example shows basic usage of an AudioContext to create an AnalyserNode ，那么 requestAnimationFrame and <canvas> to collect frequency data repeatedly and draw a "winamp bargraph style" output of the current audio input. For more examples/information, check out our Voice-change-O-matic demo (see app.js lines 128–205 for relevant code).

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: Uint8Array that the frequency domain data will be copied to.

规范

规范	状态	注释
Web 音频 API The definition of 'getByteFrequencyData()' in that specification.	工作草案

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`getByteFrequencyData`	Chrome 14	Edge 12	Firefox 25	IE 不支持 No	Opera 15	Safari 6	WebView Android Yes	Chrome Android 18	Firefox Android 26	Opera Android 14	Safari iOS 6	Samsung Internet Android 1.0

图例

完整支持
不支持

另请参阅

使用 Web 音频 API

元数据

最后修改： Feb 23, 2020

Web 音频 API
AnalyserNode
构造函数
1. AnalyserNode()
特性
方法
1. getByteFrequencyData()
2. getByteTimeDomainData()
3. getFloatFrequencyData()
4. getFloatTimeDomainData()
继承：
1. AudioNode
2. EventTarget
Related pages for Web Audio API

在此页

句法

参数

返回值

范例

参数

规范

浏览器兼容性

图例

另请参阅

相关话题