likethemammal / visualizer-micro

A JS micro library for just the getSpectrum and getWaveform methods from Dancer.js, using Web Audio API.

visualizer-micro

zero dependencies

A JS micro library for creating audio visualizers.

Simplifies the use of the HTML5 Web Audio API for retrieving audio data from an audio source.

Inspired by Dancer.js, and the getSpectrum and getWaveform methods.

Example / Demo

An example of basic install and setup can be found in the source of the Live Demo.

Install

visualizer-micro supports the UMD, meaning it supports install/usage through ES6 modules, CommonJS, AMD, and script tag globals.

Check out the dist/ directory for the minified and unminified production scripts.

npm install -d visualizer-micro

Setup

import VisualizerMicro from 'visualizer-micro'

var vm = new VisualizerMicro()

Check for browser support

Before getting any visualization data, check for browser support to make sure visualization is possible.

if (vm.isSupported()) {
    // load audio and get visualizer data
}

Load an audio source

Before you can call load(), the user has to click something. Read more about why here.

First parameter is the source for audio data. This can be an <audio> element or an instance of the HTML5 Audio() class.

Second parameter is a callback, that will be called once the audio source has been loaded for visualization.

// <audio> element
var audioEl = document.getElementById('some-audio-el')
var onLoad = function() {
    // do something after the audio source has be loaded
}

vm.load(audioEl, onLoad)

// Audio class
var audio = new Audio()

vm.load(audio, onLoad)

load() only needs to be called once per audio source. It is not necessary to call it again if audio.src is changed.

Unloading an audio source

When the audio source is no longer needed, call unload() before the audio source has been destroyed/remove/collected.

// before deleting or garbage collecting audio source

vm.unload();

Usage

getSpectrum and getWaveform

These methods retrieve the actual visualization data from the audio source. They each return arrays of numbers. They can be called anytime after an audio source is loaded, but in most cases they'll only be called if the audio source isn't paused. Generally they're only called inside an animation loop to capture the change in audio data.

// inside an animation loop..

if (!audio.paused) {
    var spectrum = vm.getSpectrum();
    
    // and/or
    
    var waveform = vm.getWaveform();
    
    // ...loop over spectrum and/or waveform array, parsing visualization numbers..
}