The getByteTimeDomainData()
method of the 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.
Syntax
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()
Parameters
array
- The
Uint8Array
that the time domain data will be copied to.
If the array has fewer elements than theAnalyserNode.fftSize
, excess elements are dropped. If it has more elements than needed, excess elements are ignored.
Return value
void
| None
Example
The following example shows basic usage of an AudioContext
to create an AnalyserNode
, then 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();
Specifications
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'getByteTimeDomainData()' in that specification. |
Working Draft |
Browser compatibility
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.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
getByteTimeDomainData | Chrome Full support 14 | Edge Full support 12 | Firefox Full support 25 | IE No support No | Opera Full support 15 | Safari Full support 6 | WebView Android Full support Yes | Chrome Android Full support 18 | Firefox Android Full support 26 | Opera Android Full support 14 | Safari iOS Full support 6 | Samsung Internet Android Full support 1.0 |
Legend
- Full support
- Full support
- No support
- No support