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.