simple_midi_player.py

from mido import MidiFile
import mido
from collections import defaultdict
import time
import sys

filename = "Space Harrier.mid"
# filename = "Shovel.mid"

if len(sys.argv) == 2:
    print("Loading from argument:", sys.argv[1])
    filename = sys.argv[1]

mid = MidiFile(filename, clip=True)
print("Loading:", mid)
print("Ticks per beat:", mid.ticks_per_beat)

song_length = 0

track_notes = []
for track_i, track in enumerate(mid.tracks):
    print("Loading track:", track_i)
    notes = defaultdict(list)
    timestamp = 0
    for msg in track:
        timestamp += msg.time
        # TODO: real datatypes for saving MIDI data chunks
        if msg.type == "note_on" or msg.type == "note_off":
            notes[timestamp].append((msg.type, msg.note, msg.velocity))
        elif msg.type == "program_change":
            notes[timestamp].append((msg.type, msg.program))
        elif msg.type == "set_tempo":
            # print(dir(msg))
            notes[timestamp].append((msg.type, msg.tempo))
        elif msg.type == "control_change":
            pass
        elif msg.type == "end_of_track":
            pass
        elif msg.type == "pitchwheel":
            pass
        elif msg.type == "track_name":
            pass
        else:
            print(timestamp, msg)
    track_notes.append(notes)
    if timestamp > song_length:
        song_length = timestamp

print("Song length:", song_length)


def play_song(player, sleng, tnotes):
    # play the song
    start = time.time()
    tempo = 500000
    for i in range(sleng):
        # convert MIDI tick to seconds
        frac_time = i * tempo * 1e-6 / mid.ticks_per_beat
        notes = []
        for ti, t in enumerate(tnotes):
            if i in t:
                for n in t[i]:
                    # n: (type, note, velocity)
                    if n[0] == "note_on":
                        player.send(mido.Message('note_on', note=n[1], velocity=n[2], channel=ti))
                    elif n[0] == "note_off":
                        player.send(mido.Message('note_off', note=n[1], velocity=n[2], channel=ti))
                    elif n[0] == "program_change":
                        player.send(mido.Message('program_change', program=n[1], channel=ti))
                    elif n[0] == "set_tempo":
                        tempo = n[1]
                    else:
                        print(n[0])
                    # if n[0] in ["note_on", "note_off"]:
                    if n[0] in ["note_on"]:
                        notes.append(
                            f"{ti}:{'+' if n[0]=='note_on' else '-'}{n[1]:02x}.{n[2]:02x} "
                        )
        if notes:
            print("".join(notes))

        # lets say 3200 time = 1 sec
        if time.time() - start < frac_time:
            while (time.time() - start) < frac_time:
                time.sleep(0.001)


print("Tracks:", len(track_notes))

out_names = mido.get_output_names()
print("Out ports:", out_names)
selected_midi_out = 1
print(out_names[selected_midi_out])
midi_out = mido.open_output(out_names[selected_midi_out])

# http://www.ccarh.org/courses/253/handout/gminstruments/
if True:
    play_song(midi_out, song_length, track_notes)

midi_out.close()