Class: Composer

Inherits:
Object show all
Defined in:
lib/composer.rb

Overview

contains the functions a music composer needs. all functions are related to music instead of audio.

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.bpm ⇒ Object

beats per minute of the track. (Set this first thing in your input file)



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# File 'lib/composer.rb', line 6

def bpm
  @bpm
end

.samplerate ⇒ Object

fames per second



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# File 'lib/composer.rb', line 8

def samplerate
  @samplerate
end

.scale ⇒ Object

the current scale to be used by many commands that require it. String. def: “major”.



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# File 'lib/composer.rb', line 10

def scale
  @scale
end

Class Method Details

.beat(beats) ⇒ Object

convert beats to seconds @beat: the beat denominator. ie 4 means 4 beats, .125 means 1 8th beat.



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# File 'lib/composer.rb', line 71

def self.beat(beats)
  bps = (self.bpm/60.0)
  return (beats) * (1.0/bps) * self.samplerate.to_f
end

.chords ⇒ Object 



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# File 'lib/composer.rb', line 12

def self.chords
  all = Hash.new
  #Triads
  all["maj"] = [4, 7] # major
  all["min"] = [3, 7] # minor
  all["aug"] = [4, 8] # augmented
  all["dim"] = [3, 6] # diminished

  #Seventh chords
  all["dim7"] = [3, 6, 9] # diminished 7th
  all["mm7"] = [3, 7, 11] # major minor 7th
  all["min7"] = [3, 7, 10] # minor 7th
  all["dom7"] = [4, 7, 10] # dominant 7th
  all["maj7"] = [4, 7, 11] # major 7th
  # half diminished
  # augmented
  # augmented major

  all["sus4"] = [5, 7]
  all["sus2"] = [2, 7]
  all["6"] = [4, 7, 9]
  all["m13"] = [2, 4, 7, 9, 11]
  all["9#11"] = [2, 4, 6, 7, 10]
  all["tonic"] = [6]
  all
end

.get_notes(notes_ar, offset = 0) ⇒ Object

return an array of notes from a array of notes with an offset, adding the root note at the start. e.g. ([1,10,2],2) outputs [2,3,0,4] (root note is 2, 10 + 2 becomes 0, 1 + 2 is 3 etc)



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# File 'lib/composer.rb', line 56

def self.get_notes(notes_ar, offset = 0)
  notes = [0] + notes_ar
  #offset
  notes.collect! do |val|
    if offset >= 0
      val+offset>11 ? val+offset-12 : val+offset
    else
      val+offset<0 ? val+offset+12 : val+offset
    end
  end
  notes
end

.matching_chords(offset = 0) ⇒ Object

return set of chord names of chords that fit in the scale, offset upward by offset notes.



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# File 'lib/composer.rb', line 77

def self.matching_chords(offset = 0)
  all = Composer.chords
  scale_n = [0] + Composer.scales[scale] # not offset at all
  out = []
  all.each do |chord|
    name = chord[0]
    notes=Composer.get_notes all[name], offset # lookup chord with name and offset
    out.push name if (scale_n&notes).sort==notes.sort # if all notes are in scale
  end
  out
end

.note_m(note) ⇒ Object

convert a note as a string to midi value

note

range: “A” to “G#”. No a flats.



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# File 'lib/composer.rb', line 91

def self.note_m(note)
  val=nil
  note.upcase!
  case note
  when 'A'
    val=0
  when 'A#'
    val=1
  when 'B'
    val=2
  when 'C'
    val=3
  when 'C#'
    val=4
  when 'D'
    val=5
  when 'D#'
    val=6
  when 'E'
    val=7
  when 'F'
    val=8
  when 'F#'
    val=9
  when 'G'
    val=10
  when 'G#'
    val=11
  else
    raise "Unknown note name recieved."
  end
  val
end

.scales ⇒ Object 



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# File 'lib/composer.rb', line 39

def self.scales
  all = Hash.new
  all["major"] = [2,4,5,7,9,11] # 7 total
  all["minor"] = [2,3,5,7,8,10]
  all["chromatic"] = *(1..10) #splat
  #all["ionian"] = [2,4,5,7,9,11]
  all["dorian"] = [2,3,5,7,9,10]
  all["phygian"] = [1,3,5,7,8,10]
  all["lydian"] = [2,4,6,7,9,11]
  all["mixolydian"] = [2,4,5,7,9,10]
  #all["aeolian"] = [2,3,5,7,8,10]
  all["locrian"] = [1,3,5,6,8,10]
  all
end