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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

getByteTimeDomainData() 方法在 AnalyserNode Interface copies the current waveform, or time-domain, data into a Uint8Array (unsigned byte 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

const audioCtx = new AudioContext();
const analyser = audioCtx.createAnalyser();
const dataArray = new Uint8Array(analyser.fftSize); // Uint8Array should be the same length as the fftSize
analyser.getByteTimeDomainData(dataArray); // fill the Uint8Array with data returned from getByteTimeDomainData()
					

参数

array

Uint8Array that the time domain data will be copied to.
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.

返回值

void | 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 demo (see app.js lines 128–205 for relevant code).

const audioCtx = new (window.AudioContext || window.webkitAudioContext)();
const analyser = audioCtx.createAnalyser();
  ...
analyser.fftSize = 2048;
const bufferLength = analyser.fftSize;
const dataArray = new Uint8Array(bufferLength);
analyser.getByteTimeDomainData(dataArray);
// draw an oscilloscope of the current audio source
function draw() {
  drawVisual = requestAnimationFrame(draw);
  analyser.getByteTimeDomainData(dataArray);
  canvasCtx.fillStyle = 'rgb(200, 200, 200)';
  canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
  canvasCtx.lineWidth = 2;
  canvasCtx.strokeStyle = 'rgb(0, 0, 0)';
  const sliceWidth = WIDTH * 1.0 / bufferLength;
  let x = 0;
  canvasCtx.beginPath();
  for(var i = 0; i < bufferLength; i++) {
    const v = dataArray[i]/128.0;
    const y = v * HEIGHT/2;
    if(i === 0)
      canvasCtx.moveTo(x, y);
    else
      canvasCtx.lineTo(x, y);
    x += sliceWidth;
  }
  canvasCtx.lineTo(WIDTH, HEIGHT/2);
  canvasCtx.stroke();
};
draw();
					

规范

规范	状态	注释
Web 音频 API The definition of 'getByteTimeDomainData()' 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
getByteTimeDomainData	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

完整支持

不支持

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

相关话题

1. AnalyserNode
2. 构造函数

   1. AnalyserNode()
3. 特性

   1. fftSize
   2. frequencyBinCount
   3. maxDecibels
   4. minDecibels
   5. smoothingTimeConstant
4. 方法

   1. getByteFrequencyData()
   2. getByteTimeDomainData()
   3. getFloatFrequencyData()
   4. getFloatTimeDomainData()
5. 继承：

   1. AudioNode
   2. EventTarget