Web/API/BaseAudioContext/createAnalyser

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 [[../../../../../../../mdn.github.io/voice-change-o-matic/index|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 APIThe definition of 'createAnalyser()' in that specification.	Working Draft

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`createAnalyser`	Chrome Full support 10 Prefixed' Full support 10 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Edge Full support ≤18	Firefox Full support 53 Notes' Full support 53 Notes' Notes' Originally implemented on `AudioContext` in Firefox 25.	IE No support No	Opera Full support 22 Full support 22 Full support 15 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Safari Full support 6 Prefixed' Full support 6 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	WebView Android Full support Yes	Chrome Android Full support 33	Firefox Android Full support 53 Notes' Full support 53 Notes' Notes' Originally implemented on `AudioContext` in Firefox Android 26.	Opera Android Full support 22 Full support 22 Full support 14 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Safari iOS Full support 6 Prefixed' Full support 6 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	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.