music-beat-detector

music-beat-detector is a library that analyzes a music stream and detects any beat. It can be used to control lights or any magic effect by the music wave.

Bundled with this library there are three components:

• MusicBeatDetector is able to analyze any PCM 16bit Little Endian audio stream. It detects music peaks and realtime bpm.
• MusicBeatScheduler is able to sync any detected peak with the listened audio. It's useful to control some lights or any other effect.
• MusicGraph generates an SVG graph that displays every detected peak. It's useful to tune the peak detection.

Example

const fs = require('fs')
const Speaker = require('speaker')
const createMusicStream = require('create-music-stream') //read this https://github.com/chrvadala/create-music-stream#faq
const {MusicBeatDetector, MusicBeatScheduler, MusicGraph} = require('music-beat-detector')

const musicSource = process.argv[2] //get the first argument on cli

const musicGraph = new MusicGraph()

const musicBeatScheduler = new MusicBeatScheduler(pos => {
  console.log(`peak at ${pos}ms`) // your music effect goes here
})

const musicBeatDetector = new MusicBeatDetector({
  plotter: musicGraph.getPlotter(),
  scheduler: musicBeatScheduler.getScheduler(),
})

createMusicStream(musicSource)
  .pipe(musicBeatDetector.getAnalyzer())
  .on('peak-detected', (pos, bpm) => console.log(`peak-detected at ${pos}ms, detected bpm ${bpm}`))
  .on('end', () => {
    fs.writeFileSync('graph.svg', musicGraph.getSVG())
    console.log('end')
  })

  .pipe(new Speaker())
  .on('open', () => musicBeatScheduler.start())

Usage

You can play any music sound supported by the library create-music-stream. Note: The beat detection performs better on mp3 files than YouTube video.

node example.js ./track.mp3
node example.js https://www.youtube.com/watch?v=qeMFqkcPYcg
node example.js https://www.youtube.com/watch?v=Zi_XLOBDo_Y
node example.js https://www.youtube.com/watch?v=n_GFN3a0yj0
node example.js https://www.youtube.com/watch?v=59Q_lhgGANc

Reference

new MusicBeatDetector(options)

Param	Default	Description
options.sensitivity	0.6	Response to the music wave (value from 0.5 to 1)
options.plotter	-	Instance of MusicGraph
options.scheduler	-	Instance of MusicBeatScheduler
options.minThreashold	1638	Peaks under this level are ignored (usually they're noise)
options.debugFilter	false	Stream the filtered music throught the lowpass filter (for debug purpose)

• getAnalyzer() - Returns a transformer stream that analyze the music

new MusicBeatScheduler(effectCallback)

• getScheduler() - returns an instance used by MusicBeatDetector
• start() - start effects (usually controlled by speaker events)

new MusicGraph(secondWidth, secondHeight)

• getPlotter() - returns an instance used by MusicBeatDetector
• getSVG() - returns a string with the SVG that displays the analyzed music

Contributors

• chrvadala (author)