peas 0.3 released

Peas defines constants from music theory and allows one to perform math with them. Currently supports pitches (as MIDI values), pitch classes, and intervals using semitones, wholetones, chromatic, latin or diatonic abbreviations.

Coming soon: circles (as in ‘circle of fifths’), scales, chords and chord progressions.

Code available on github.

Features

• Defines common music theory constants:
  
  • PitchClass: C, Ds, Eb, etc
    
  • Pitch (as a MIDI value): C4, Ds5, Gb8, etc
    
  • Intervals:
    
    • Semitone: S0, S1, S2 … S127
      
    • Wholetone: W0, W1, W2 … W63
      
    • Chromatic: d2, A1, d3, A2 … A7
      
    • Latin: S, T and TT (semi, whole and tritones)
      
    • Diatonic: P1, m2, M2, m3, M3, P4, A4, d5, P5, m6, M6, m7, M7 and P8
      
• Constants output as their name (done using named_value_class)
  
• Adds helpers to Fixnum: 2.octaves, 3.semitones, 4.major_seconds, etc.
  

Installation

gem install peas

Requirements

Currently only tested with Ruby 1.9.2-p290.  named_value_class 0.7 gem required.

Usage

require 'peas'

include Peas::Pitches
include Peas::Intervals

def play_midi_note(pitch)
  # maybe use arirusso/micromidi here  
end

[Ab3,G3,Ab3,C2].each do |root_pitch|
  [P1,m3,P5,P5,d5].each do |interval|
    play_midi_note(root_pitch + interval)
    play_midi_note(root_pitch + interval + 2.octaves)
    play_midi_note(root_pitch - 2.tritones)
  end
end