The createAnalyser()
method of the BaseAudioContext
interface creates an AnalyserNode
, which can be used to expose audio time and frequency data and create data visualisations.
Note: For more on using this node, see the AnalyserNode
page.
Syntax
var analyserNode = baseAudioContext.createAnalyser();
Returns
An AnalyserNode
.
Example
The following example shows basic usage of an AudioContext to create an Analyser node, then use requestAnimationFrame() 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).
var audioCtx = new (window.AudioContext || window.webkitAudioContext)(); var analyser = audioCtx.createAnalyser(); ... analyser.fftSize = 2048; var bufferLength = analyser.frequencyBinCount; var 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)'; canvasCtx.beginPath(); var sliceWidth = WIDTH * 1.0 / bufferLength; var x = 0; for(var i = 0; i < bufferLength; i++) { var v = dataArray[i] / 128.0; var y = v * HEIGHT/2; if(i === 0) { canvasCtx.moveTo(x, y); } else { canvasCtx.lineTo(x, y); } x += sliceWidth; } canvasCtx.lineTo(canvas.width, canvas.height/2); canvasCtx.stroke(); }; draw();
Specifications
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'createAnalyser()' 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 | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
createAnalyser | Chrome
Full support
10
| Edge Full support ≤18 | Firefox
Full support
53
| IE No support No | Opera
Full support
22
| Safari
Full support
6
| WebView Android Full support Yes | Chrome Android Full support 33 | Firefox Android
Full support
53
| Opera Android
Full support
22
| Safari iOS
Full support
6
| Samsung Internet Android Full support 2.0 |
Legend
- Full support
- Full support
- No support
- No support
- See implementation notes.
- See implementation notes.
- Requires a vendor prefix or different name for use.
- Requires a vendor prefix or different name for use.