gcode_midi_2.py

import mido
import os
import math
from song import Note

FILENAME = "/home/pi/Dark_World_Theme.mid"
OUTPUT_FOLDER = "~/3D Printing/"
OUTPUT_NAME = 'DarkWorldTheme-'

# MIDI takes a number from 0 to 127 to represent the notes for the following frequencies
NOTES = [8.18, 8.66, 9.18, 9.72, 10.30, 10.91, 11.56, 12.25, 12.98, 13.75, 14.57, 15.43, 16.35,
        17.32, 18.35, 19.45, 20.60, 21.83, 23.12, 24.50, 25.96, 27.50, 29.14, 30.87, 32.70,
        34.65, 36.71, 38.89, 41.20, 43.65, 46.25, 49.00, 51.91, 55.00, 58.27, 61.74, 65.41,
        69.30, 73.42, 77.78, 82.41, 87.31, 92.50, 98.00, 103.83, 110.00, 116.54, 123.47,
        130.81, 138.59, 146.83, 155.56, 164.81, 174.61, 185.00, 196.00, 207.65, 220.00, 233.08,
        246.94, 261.63, 277.18, 293.66, 311.13, 329.63, 349.23, 369.99, 392.00, 415.30, 440.00,
        466.16, 493.88, 523.25, 554.37, 587.33, 622.25, 659.26, 698.46, 739.99, 783.99, 830.61,
        880.00, 932.33, 987.77, 1046.50, 1108.73, 1174.66, 1244.51, 1318.51, 1396.91, 1479.98,
        1567.98, 1661.22, 1760.00, 1864.66, 1975.53, 2093.00, 2217.46, 2349.32, 2489.02,
        2637.02, 2793.83, 2959.96, 3135.96, 3322.44, 3520.00, 3729.31, 3951.07, 4186.01,
        4434.92, 4698.64, 4978.03, 5274.04, 5587.65, 5919.91, 6271.93, 6644.88, 7040.00,
        7458.62, 7902.13, 8372.02, 8869.84, 9397.27, 9956.06, 10548.08, 11175.30, 11839.82,
        12543.85, 13289.75]

# The speed offset of the printer. Adjusting this will 'tune' the printer
VELOCITY_MULT = 5
AXIS = 'Y'
MIN = 0
MAX = 150
START = (MIN + MAX)//2
START_INSTRUCTIONS = "G26\nG21\nG90\nG28\nG1 {}{} F{}\nG4 P1000\n".format(AXIS, START, (600*VELOCITY_MULT))
END_INSTRUCTIONS = "\nG4 P1000\nG1 {}{} F{}\n".format(AXIS, START, int(600*VELOCITY_MULT))

def main():

    notes = notes_from_file(FILENAME)
    for channel in notes:
        print(channel, len(notes[channel]))

    full_export(notes, OUTPUT_FOLDER, OUTPUT_NAME)
    
def notes_from_file(filename):

    mid = mido.MidiFile(FILENAME)
    tpb = mid.ticks_per_beat
    tps = 8000*tpb

    notes = {}
    start_times = {}

    for track in mid.tracks:
        for note in track:
            if hasattr(note, 'channel') and note.channel not in notes:
                notes[note.channel] = []

    for track in mid.tracks:
        abstime = 0

        for note in track:
            abstime += note.time / tps
            if note.type == 'note_on' and note.velocity != 0:
                start_times[note.channel] = abstime
            elif note.type =='note_off' or (note.type == 'note_on' and note.velocity == 0):
                notes[note.channel].append(Note(note.note, int(start_times[note.channel]*1000), int((abstime - start_times[note.channel])*1000)))
            elif note.type == 'set_tempo':
                tps = 1000000/note.tempo*tpb

    return notes

def convert_notes(notes):

    gcode = ''
    pos = START
    new_positions = []

    i = 0
    current_time = 0

    for note in notes:

        # Calculate distance and velocity
        velocity = NOTES[note.note] * VELOCITY_MULT
        distance = velocity * note.length / 60000 # notes are in miliseconds

        # Try to go towards max Y. If it doesn't fit, go towards min Y. If neither fit, go back and forth as much as required.
        while distance > 0:
            if pos + distance <= MAX:
                pos += distance
                new_positions.append(pos)
                distance = 0
            elif pos - distance >= MIN:
                pos -= distance
                new_positions.append(pos)
                distance = 0
            elif pos + distance - MAX < distance - pos + MIN:
                new_positions.append(MAX)
                distance -= MAX - pos
                pos = MAX
            else:
                new_positions.append(MIN)
                distance -= pos - MIN
                pos = MIN

        # Write GCode to string
        gcode += "G4 P{}\n".format(note.time - current_time)
        for new_pos in new_positions:
            gcode += "G1 {}{} F{}\n".format(AXIS, int(new_pos), int(velocity))

        # Prepare for next note
        new_positions.clear()
        current_time = note.time + note.length

    return gcode
            
def full_export(notes, folder, filename):
    for track in notes:
        export_gcode(os.path.join(folder, filename + str(track) + '.gcode'), convert_notes(notes[track]))

def export_gcode(filename, gcode):

    with open(filename, 'w') as file:
        file.write(START_INSTRUCTIONS + gcode + END_INSTRUCTIONS)

#main()