AnalyserNode.getFloatTimeDomainData()

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getFloatTimeDomainData() 方法在 AnalyserNode Interface copies the current waveform, or time-domain, data into a Float32Array array passed into it.

If the array has fewer elements than the AnalyserNode.fftSize , 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 Float32Array(analyser.fftSize); // Float32Array needs to be the same length as the fftSize
analyser.getFloatTimeDomainData(dataArray); // fill the Float32Array with data returned from getFloatTimeDomainData()

参数

array: Float32Array that the time domain data will be copied to.
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 time domain data repeatedly and draw an "oscilloscope style" output of the current audio input. For more complete applied examples/information, check out our Voice-change-O-matic-float-data demo (see the 源代码 too).

var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var analyser = audioCtx.createAnalyser();
  ...
analyser.fftSize = 1024;
var bufferLength = analyser.fftSize;
console.log(bufferLength);
var dataArray = new Float32Array(bufferLength);
canvasCtx.clearRect(0, 0, WIDTH, HEIGHT);
function draw() {
  drawVisual = requestAnimationFrame(draw);
  analyser.getFloatTimeDomainData(dataArray);
  canvasCtx.fillStyle = 'rgb(200, 200, 200)';
  canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
  canvasCtx.lineWidth = 2;
  canvasCtx.strokeStyle = 'rgb(0, 0, 0)';
  canvasCtx.beginPath();
  var sliceWidth = WIDTH * 1.0 / bufferLength;
  var x = 0;
  for(var i = 0; i < bufferLength; i++) {
    var v = dataArray[i] * 200.0;
    var y = HEIGHT/2 + v;
    if(i === 0) {
      canvasCtx.moveTo(x, y);
    } else {
      canvasCtx.lineTo(x, y);
    }
    x += sliceWidth;
  }
  canvasCtx.lineTo(canvas.width, canvas.height/2);
  canvasCtx.stroke();
};
draw();

参数

array: Float32Array that the time domain data will be copied to.

规范

规范	状态	注释
Web 音频 API The definition of 'getFloatTimeDomainData()' 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
`getFloatTimeDomainData`	Chrome 14	Edge 12	Firefox 25	IE 不支持 No	Opera 15	Safari 不支持 No	WebView Android Yes	Chrome Android 18	Firefox Android 26	Opera Android 14	Safari iOS 不支持 No	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： 2020 年 1 月 22 日

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