Module: MIDIOps::Note

Defined in:
lib/midiops/note.rb

Constant Summary collapse

KEY_OFFSETS = 
{
  C: 0,

  Csharp: 1,
  Dflat: 1,

  D: 2,

  Dsharp: 3,
  Eflat: 3,

  E: 4,

  F: 5,

  Fsharp: 6,
  Gflat: 6,

  G: 7,

  Gsharp: 8,
  Aflat: 8,

  A: 9,

  Asharp: 10,
  Bflat: 10,

  B: 11
}

Class Method Summary collapse

Class Method Details

.key_to_code(key, octave) ⇒ Object 



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# File 'lib/midiops/note.rb', line 35

def key_to_code key, octave
  KEY_OFFSETS[key] + 12 + (12 * octave)
end

.note_to_code(note) ⇒ Object 



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# File 'lib/midiops/note.rb', line 57

def note_to_code note
  res = parse_note note
  key_to_code res[:key], res[:octave]
end

.parse_note(note) ⇒ Object 



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# File 'lib/midiops/note.rb', line 39

def parse_note note
  # formats to accept: "C3" / "B-1" / "C#4" (sharp) / "Db5" (flat)

  case note
  when /^([A-Ga-g])(-?[0-9]{1,2})$/
    m = $~.captures
    {key: m[0].upcase.to_sym, octave: m[1].to_i}
  when /^([CDFGAcdfga])\#(-?[0-9]{1,2})$/
    m = $~.captures
    {key: "#{m[0].upcase}sharp".to_sym, octave: m[1].to_i}
  when /^([DEGABdegab])b(-?[0-9]{1,2})$/
    m = $~.captures
    {key: "#{m[0].upcase}flat".to_sym, octave: m[1].to_i}
  else
    raise RuntimeError, "Invalid note format: #{note}"
  end
end