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MIDI
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| import music21 | |
| path = 'data/exodus/ambrosia.midi' | |
| score = music21.converter.parse(path, forceSource=True, quantizePost=False) | |
| # validate time signature is 4/4 | |
| time_signature = score.parts[0].timeSignature | |
| if time_signature: assert time_signature.ratioString == '4/4' | |
| # validate mode is major / minor | |
| key = score.analyze('key') | |
| assert key.mode == 'minor' or key.mode == 'major' | |
| # transpose to c major / a minor | |
| interval = 60 - key.tonic.midi | |
| if key.mode == 'minor': interval -= 3 | |
| score = score.transpose(interval) | |
| # convert midi to string | |
| s = '' | |
| last_offset = 0 | |
| for n in score.flat.notes: | |
| if not isinstance(n, music21.chord.Chord): | |
| note = n.pitch.midi | |
| duration = n.duration.type # n.duration.quarterLength | |
| offset = n.offset | |
| delta = offset - last_offset | |
| if delta: s += 'wait_{} '.format(delta) | |
| s += 'note_{}_{} '.format(note, duration) | |
| last_offset = offset | |
| # convert string back to midi | |
| from fractions import Fraction | |
| d = { | |
| '32nd': 1/32, | |
| '16th': 1/16, | |
| 'eighth': 1/8, | |
| 'quarter': 1/4, | |
| 'half': 1/2, | |
| 'whole': 1, | |
| } | |
| time = 0 | |
| stream = music21.stream.Stream() | |
| for i in s.split(): | |
| if i.startswith('note'): | |
| note, duration = i.lstrip('note_').split('_') | |
| n = music21.note.Note(int(note)) | |
| n.duration.type = duration | |
| stream.insertIntoNoteOrChord(time, n) | |
| elif i.startswith('wait'): | |
| duration = float(Fraction(i.lstrip('wait_'))) | |
| time += duration | |
| else: | |
| print('did not expect', i) | |
| stream.write('midi', fp='yeet.midi') | |
| # play the result | |
| stream.show('midi') |
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