meyda: A JavaScript repository from felakuti4life

#meyda

is a javascript audio feature extraction library designed for and implemented in the Web Audio API.

hughrawlinson | nevosegal | jakubfiala

###Currently supported features #####(inspired by the yaafe library)

rms
energy
zcr
complexSpectrum
amplitudeSpectrum
powerSpectrum
spectralCentroid
spectralFlatness
spectralSlope
spectralRolloff
spectralSpread
spectralSkewness
spectralKurtosis
loudness
- specific
- total
perceptualSpread
perceptualSharpness
mfcc

For a detailed description of the above features (and other functions in Meyda), see the docs.md file.

###Setup

Supported Browsers: Chrome, Firefox, Opera. Safari works, unless you're using a MediaElementSource.

Download meyda.min.js and include it within the <head> tag your HTML.

<script type="text/javascript" src="meyda.min.js"></script>

In your javascript, initialize Meyda with the desired buffer size as follows:

// get context
window.AudioContext = window.AudioContext || window.webkitAudioContext;
var context = new AudioContext();

// create source node (this could be any kind of Web Audio Buffer source or a Media Element/Media Stream source)
// in Safari, use a buffer source instead
var tune = new Audio('audio/guitar.mp3');
window.source = context.createMediaElementSource(tune);

// instantiate new meyda with buffer size of 512 (default is 256)
var meyda = new Meyda(context,source,512);

Use the get function to extract a desired feature in real time

var rootMeanSquare = meyda.get("rms");

You can also pass an array of strings to get multiple features at a time

var myFeatures = meyda.get(["rms", "loudness", "spectralCentroid"]);

Alternatively, you can use snychronized buffer-by-buffer extraction by specifying a callback when constructing Meyda

//instantiate new meyda with callback
var meyda = new Meyda(context, source, 512, function(output){
	myFeatures = output;
});

//commence extraction with specified features
meyda.start(["zcr", "spectralSlope"]);

//stop extraction whenever we want (e.g. after 3 seconds)
setTimeout(function() {
	meyda.stop();
}, 3000);

You can obtain information about the extractors' output by querying the featureInfo object meyda.featureInfo['zcr'].type; The return type of features can be either 'Number', 'Array', or 'multipleArrays', and the object definition can be found in meyda.js.

###Acknowledgements

This library is using the jsfft implementation by Nick Jones released under the MIT License. The authors would like to thank Rebecca Fiebrink for essential guidance and support.

felakuti4life/meyda