README.md

wav-spectrogram

A Node.js library for loading WAV files and drawing a spectrogram to a canvas.

Usage

Load WAV file using a input object, read contents as an array buffer and pass to function with a canvas of the desired dimensions:

var wavSpectro = require('wav-spectrogram');

var fileInput = document.getElementById('file-input');
var canvasElem = document.getElementById('spectrogram-canvas');

var reader = new FileReader();

reader.onload = function() {

    var arrayBuffer = reader.result;

    wavSpectro.drawSpectrogram({arrayBuffer: arrayBuffer, canvasElem: canvasElem, cmap: 'jet'}, function () {
    
        console.log("Done.");
    
    });

};

reader.readAsArrayBuffer(fileInput.files[0]);

Functions

The draw function must be handed parameters in an object, named as such. Parameters with default values can be left out.

Option	Default	Description
arrayBuffer	-	Array buffer read from WAV file
canvasElem	-	Canvas element to draw to (spectrogram will fill dimensions)
cmap	-	Colour map to draw using colormap module
nfft	512	Buffer size of Fast Fourier Transform
frameLengthMs	0.1	Length of frames signal is divided into before FFT is applied (given in milliseconds)
frameStepMs	0.005	Size of steps forward each frame takes (if less than frameLengthMs then frames overlap)
errorHandler	-	An error handling function which will be called if loading the wav file fails

As well as the params object, the draw function accepts a callback function.