midiconvert.py

NOTES = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B']
OCTAVES = list(range(11))
NOTES_IN_OCTAVE = len(NOTES)

errors = {
    'program': 'Bad input, please refer this spec-\n'
               'http://www.electronics.dit.ie/staff/tscarff/Music_technology/midi/program_change.htm',
    'notes': 'Bad input, please refer this spec-\n'
             'http://www.electronics.dit.ie/staff/tscarff/Music_technology/midi/midi_note_numbers_for_octaves.htm'
}


def number_to_note(number):
    octave = number // NOTES_IN_OCTAVE
    assert octave in OCTAVES, errors['notes']
    assert 0 <= number <= 127, errors['notes']
    note = NOTES[number % NOTES_IN_OCTAVE]

    return note, octave


def note_to_number(note, octave):
    assert note in NOTES, errors['notes']
    assert octave in OCTAVES, errors['notes']

    note = NOTES.index(note)
    note += (NOTES_IN_OCTAVE * octave)

    assert 0 <= note <= 127, errors['notes']

    return note