midi2text.py

import glob
from music21 import converter, instrument, note, chord, interval, pitch
import sys
from tqdm import tqdm

def valid_note(note_number):
    return -12*5 <= note_number <= 12*5

def first_note(notes_to_parse):
    for element in notes_to_parse:
        try:
            if isinstance(element, note.Note):
                return int(element.pitch.ps)
            if isinstance(element, chord.Chord):
                return int(element.notes[-1].pitch.ps)
        except:
            pass
    return 60

def midi2text(midis_folder):
    """ Get all the notes and chords from the midi files in the ./midi_songs directory """
    notes = []

    midis = sorted(glob.glob(f"{midis_folder}/*.mid"))

    for file in tqdm(midis):
        try:
            midi = converter.parse(file)

            # Transpose to C
            k = midi.analyze('key')
            i = interval.Interval(k.tonic, pitch.Pitch('C4'))
            midi = midi.transpose(i)
            mode = str(k.mode)

            #print("Parsing %s" % file)

            notes_to_parse = None

            try: # file has instrument parts
                s2 = instrument.partitionByInstrument(midi)
                notes_to_parse = s2.parts[0].recurse() 
            except: # file has notes in a flat structure
                notes_to_parse = midi.flat.notes

            notes.append(f"{mode} =>")

            last_note = first_note(notes_to_parse)

            for element in notes_to_parse:
                try:
                    #print(last_note)
                    if isinstance(element, note.Note):
                        duration = element.duration.quarterLength
                        new_note = int(element.pitch.ps)

                        if duration > 0 and valid_note(new_note - last_note):
                            notes.append(f"{str(new_note - last_note)}|{duration}")
                            last_note = new_note
                    elif isinstance(element, note.Rest):
                        duration = element.duration.quarterLength
                        if 0 < duration < 32:
                            notes.append(f"R|{duration}")
                    elif isinstance(element, chord.Chord):
                        duration = element.duration.quarterLength
                        chord_notes = [int(new_note.pitch.ps)-last_note for new_note in element.notes if valid_note(int(new_note.pitch.ps)-last_note)]
                        if duration > 0 and len(chord_notes) > 0:
                            notes.append('.'.join(map(str,chord_notes)) + "|" + str(duration))
                            last_note = int(element.notes[0].pitch.ps)
                except:
                    pass
            notes.append("\n")
        except:
            pass
    with open('notes.txt', 'w') as filepath:
        filepath.write(" ".join(notes).replace("\n ","\n").strip())

if __name__ == '__main__':
    midis_folder = sys.argv[1]
    midi2text(midis_folder)