The getFloatTimeDomainData()
method of the 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.
Syntax
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(myDataArray); // fill the Float32Array with data returned from getFloatTimeDomainData()
Returns
A Float32Array
.
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-float-data demo (see the source code 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();
Parameters
- array
- The
Float32Array
that the time domain data will be copied to.
Specifications
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'getFloatTimeDomainData()' in that specification. |
Working Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 10.0webkit | 25.0 (25.0) | Not supported | 15.0webkit 22 (unprefixed) |
6.0webkit |
Feature | Android | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|
Basic support | ? | 26.0 | 1.2 | ? | ? | ? | 33.0 |
See also
Document Tags and Contributors
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Contributors to this page:
teoli,
chrisdavidmills
Last updated by:
teoli,