AutoComposerJS

See it in action here!

Overview

AutoComposerJS creates small musical snippets that conform to the best practices of Western music theory. In its current form, it does this by writing a simple melody over a chord progression. It also has a few more tricks:

Writes basic accompaniment for melodies.
Can present generated melodies in the following formats:
- Musical score
- MIDI file
- Audio - the program play back generated MIDI files in the browser

If you're a music nerd that frequently wonders about the melodic possibilities in a chord progression, this program can help you out. It visualizes various sequences of chord tones that fit in a chord progression, and ranks them by smoothness. In our case, smoothness is calculated as the sum of intervals between the notes of a melody.

Usage

Install the package through NPM

npm install --save autocomposer-js

And then it'll be usable in your code!

var AutoComposerJS = require('autocomposer-js')
var chordProgression = "Gm Em C D".split(" ")
var allTheMelodies = AutoComposerJS.melody.buildSimpleMelodies(chordProgression)

Or just drop the file in dist/ through a script tag like so:

<script src="path/to/autocomposer-js.js"></script>
<script>
  var chordProgression = "Gm Em C D".split(" ")
  var allTheMelodies = AutoComposerJS.melody.buildSimpleMelodies(chordProgression)
</script>

The melodies will be returned as MelodyData objects, which look like this:

{
   "chordProgression":[
      "Gm",
      "D7"
   ],
   "melodyNotes":[
      "D5",
      "C5"
   ],
   "smoothness":2,
   "range":2,
   "melodyString":"D5 C5"
}

The range is the distance between the highest and lowest note (in semitones). The smoothness shows the total distance between all notes in the melody (in semitones).

Browserify

If you're going to use this for a web app of some sort and you're going to Browserify it, use src/browser-build.js as your target. This will include the MIDI player which can play all those nice melodies on a browser.

Potential Uses

Brainstorming when starting or continuing a musical composition.
Exploring how melody and harmony work together.

More info