source/tokensequence.py

import note_seq
import numpy as np
from PIL import Image

NOTE_LENGTH_16TH_120BPM = 0.25 * 60 / 120
BAR_LENGTH_120BPM = 4.0 * 60 / 120
SAMPLE_RATE=44100

def token_sequence_to_audio(token_sequence):
    note_sequence = token_sequence_to_note_sequence(token_sequence)
    synth = note_seq.midi_synth.fluidsynth
    array_of_floats = synth(note_sequence, sample_rate=SAMPLE_RATE)
    note_plot = note_seq.plot_sequence(note_sequence, False)
    array_of_floats /=1.414
    array_of_floats *= 32767
    int16_data = array_of_floats.astype(np.int16)
    return SAMPLE_RATE, int16_data

def token_sequence_to_image(token_sequence):
    
    note_sequence = token_sequence_to_note_sequence(token_sequence)

    # Find minumum and maximum pitch.
    min_pitch = 128
    max_pitch = 0
    for note in note_sequence.notes:
        if note.pitch < min_pitch:
            min_pitch = note.pitch
        if note.pitch > max_pitch:
            max_pitch = note.pitch

    image_height = max_pitch - min_pitch + 1
    image_width = int(16 * 4)

    color = (12, 12, 12)

    # Indicate that this bar was used for composition.
    image = Image.new("RGB", (image_width, image_height), color)

    # colors = [(0, 0, 0), (255, 255, 255), (255, 0, 0), (0, 255, 0), (0, 0, 255), (255, 255, 0), (255, 0, 255), (0, 255, 255)]
    colors = [(248, 249, 250), (233, 236, 239), (173, 181, 189), (52, 58, 64)]

    instrument_to_color_index = {}

    # Draw the notes.
    for note in note_sequence.notes:
        x = int(note.start_time / note_sequence.total_time * image_width)
        y = note.pitch - min_pitch
        width = int((note.end_time - note.start_time) / note_sequence.total_time * image_width)
        height = 1

        if note.instrument not in instrument_to_color_index:
            instrument_to_color_index[note.instrument] = len(instrument_to_color_index)
        color_index = instrument_to_color_index[note.instrument]
        color = colors[color_index]

        #color = (255, 255, 255)
        image.paste(color, (x, y, x + width, y + height))

    # Rescale and rotate.
    factor = 8
    image = image.resize((image_width * factor, image_height * factor), Image.NEAREST)
    image = image.transpose(Image.FLIP_TOP_BOTTOM)

    return image
    
    
    

def token_sequence_to_note_sequence(token_sequence, use_program=True, use_drums=True, instrument_mapper=None, only_piano=False):
    if isinstance(token_sequence, str):
        token_sequence = token_sequence.split()
    note_sequence = empty_note_sequence()

    # Render all notes.
    current_program = 1
    current_is_drum = False
    current_instrument = 0
    track_count = 0
    for token_index, token in enumerate(token_sequence):

        if token == "PIECE_START":
            pass
        elif token == "PIECE_END":
            print("The end.")
            break
        elif token == "TRACK_START":
            current_bar_index = 0
            track_count += 1
            pass
        elif token == "TRACK_END":
            pass
        elif token.startswith("INST"):
            instrument = token.split("=")[-1]
            if instrument != "DRUMS" and use_program:
                if instrument_mapper is not None:
                    if instrument in instrument_mapper:
                        instrument = instrument_mapper[instrument]
                current_program = int(instrument)
                current_instrument = track_count
                current_is_drum = False
            if instrument == "DRUMS" and use_drums:
                current_instrument = 0
                current_program = 0
                current_is_drum = True
        elif token == "BAR_START":
            current_time = current_bar_index * BAR_LENGTH_120BPM
            current_notes = {}
        elif token == "BAR_END":
            current_bar_index += 1
            pass
        elif token.startswith("NOTE_ON"):
            pitch = int(token.split("=")[-1])
            note = note_sequence.notes.add()
            note.start_time = current_time
            note.end_time = current_time + 4 * NOTE_LENGTH_16TH_120BPM
            note.pitch = pitch
            note.instrument = current_instrument
            note.program = current_program
            note.velocity = 80
            note.is_drum = current_is_drum
            current_notes[pitch] = note
        elif token.startswith("NOTE_OFF"):
            pitch = int(token.split("=")[-1])
            if pitch in current_notes:
                note = current_notes[pitch]
                note.end_time = current_time
        elif token.startswith("TIME_DELTA"):
            delta = float(token.split("=")[-1]) * NOTE_LENGTH_16TH_120BPM
            current_time += delta
        elif token.startswith("DENSITY="):
            pass
        elif token == "[PAD]":
            pass
        else:
            pass

    # Make the instruments right.
    instruments_drums = []
    for note in note_sequence.notes:
        pair = [note.program, note.is_drum]
        if pair not in instruments_drums:
            instruments_drums += [pair]
        note.instrument = instruments_drums.index(pair)

    if only_piano:
        for note in note_sequence.notes:
            if not note.is_drum:
                note.instrument = 0
                note.program = 0

    note_sequence.total_time = current_time

    return note_sequence

def empty_note_sequence(qpm=120.0, total_time=0.0):
    note_sequence = note_seq.protobuf.music_pb2.NoteSequence()
    note_sequence.tempos.add().qpm = qpm
    note_sequence.ticks_per_quarter = note_seq.constants.STANDARD_PPQ
    note_sequence.total_time = total_time
    return note_sequence