text2midi.py

import numpy
from music21 import instrument, note, stream, chord
import sys
import numpy as np

def convert_to_float(frac_str):
    try:
        return float(frac_str)
    except ValueError:
        num, denom = frac_str.split('/')
        try:
            leading, num = num.split(' ')
            whole = float(leading)
        except ValueError:
            whole = 0
        frac = float(num) / float(denom)
        return whole - frac if whole < 0 else whole + frac

def note_number_to_name(note_number):
    #print(note_number)
    semis = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B']

    # Ensure the note is an int
    note_number = int(np.round(note_number))

    # Get the semitone and the octave, and concatenate to create the name
    output = semis[note_number % 12] + str(note_number//12 - 1)
    #print(output)
    return output


def duration(note_text):
    if "|" in note_text:
        return convert_to_float(note_text.split("|")[-1])
    # It's invalid but's let's return 0.5 to make it more resilient
    else:
        return 0.5

def create_midi(notes_sequence,output_file="output.mid"):
    offset = 0
    output_notes = []

    prev_note = 60
    # create note and chord objects based on the values generated by the model
    for token in notes_sequence:
        # starting token
        if token == "S":
            continue
        token_duration = duration(token)
        token = token.split("|")[0]

        # token is a chord
        if '.' in token:
            notes_in_chord = token.split('.')
            notes = []
            for current_note in notes_in_chord:

                new_note = note.Note(note_number_to_name(prev_note+int(current_note)))
                new_note.storedInstrument = instrument.Piano()
                notes.append(new_note)
            prev_note = int(notes_in_chord[0]) + prev_note
            new_chord = chord.Chord(notes,quarterLength=token_duration)
            new_chord.offset = offset
            output_notes.append(new_chord)
        # token is a rest
        elif "R" in token:
            output_notes.append(note.Rest(quarterLength=token_duration))
        # token is a single note
        else:
            new_note = note.Note(note_number_to_name(prev_note+int(token)),quarterLength=token_duration)
            prev_note = int(token) + prev_note
            new_note.offset = offset
            new_note.storedInstrument = instrument.Piano()
            output_notes.append(new_note)

        # increase offset each iteration so that notes do not stack
        offset += token_duration

    midi_stream = stream.Stream(output_notes)

    midi_stream.write('midi', fp=output_file)

if __name__ == '__main__':
    notes_sequence = sys.argv[1].split()[2:]
    if len(sys.argv) > 2:
        output_path = sys.argv[2]
        create_midi(notes_sequence,output_path)
    else:
        create_midi(notes_sequence)