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 [[../../../../../../../mdn.github.io/voice-change-o-matic/index|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 APIThe 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.
Update compatibility data on GitHub
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
See also
AnalyserNode.getByteTimeDomainData() by Mozilla Contributors is licensed under CC-BY-SA 2.5.