Midified

 from mido import MidiFile, MidiTrack, Message

import numpy as np

num_notes = 96

samples_per_measure = 96

def midi_to_samples(fname):

has_time_sig = False

flag_warning = False

mid = MidiFile(fname)

ticks_per_beat = mid.ticks_per_beat

ticks_per_measure = 4 * ticks_per_beat

for i, track in enumerate(mid.tracks):

for msg in track:

if msg.type == 'time_signature':

new_tpm = msg.numerator * ticks_per_beat * 4 / msg.denominator

if has_time_sig and new_tpm != ticks_per_measure:

flag_warning = True

ticks_per_measure = new_tpm

has_time_sig = True

if flag_warning:

print "  ^^^^^^ WARNING ^^^^^^"

print "    " + fname

print "    Detected multiple distinct time signatures."

print "  ^^^^^^ WARNING ^^^^^^"

return []

all_notes = {}

for i, track in enumerate(mid.tracks):

abs_time = 0

for msg in track:

abs_time += msg.time

if msg.type == 'note_on':

if msg.velocity == 0:

continue

note = msg.note - (128 - num_notes)/2

assert(note >= 0 and note < num_notes)

if note not in all_notes:

all_notes[note] = []

else:

single_note = all_notes[note][-1]

if len(single_note) == 1:

single_note.append(single_note[0] + 1)

all_notes[note].append([abs_time * samples_per_measure / ticks_per_measure])

elif msg.type == 'note_off':

if len(all_notes[note][-1]) != 1:

continue

all_notes[note][-1].append(abs_time * samples_per_measure / ticks_per_measure)

for note in all_notes:

for start_end in all_notes[note]:

if len(start_end) == 1:

start_end.append(start_end[0] + 1)

samples = []

for note in all_notes:

for start, end in all_notes[note]:

sample_ix = start / samples_per_measure

while len(samples) <= sample_ix:

samples.append(np.zeros((samples_per_measure, num_notes), dtype=np.uint8))

sample = samples[sample_ix]

start_ix = start - sample_ix * samples_per_measure

if False:

end_ix = min(end - sample_ix * samples_per_measure, samples_per_measure)

while start_ix < end_ix:

sample[start_ix, note] = 1

start_ix += 1

else:

sample[start_ix, note] = 1

return samples

def samples_to_midi(samples, fname, ticks_per_sample, thresh=0.5):

mid = MidiFile()

track = MidiTrack()

mid.tracks.append(track)

ticks_per_beat = mid.ticks_per_beat

ticks_per_measure = 4 * ticks_per_beat

ticks_per_sample = ticks_per_measure / samples_per_measure

abs_time = 0

last_time = 0

for sample in samples:

for y in xrange(sample.shape[0]):

abs_time += ticks_per_sample

for x in xrange(sample.shape[1]):

note = x + (128 - num_notes)/2

if sample[y,x] >= thresh and (y == 0 or sample[y-1,x] < thresh):

delta_time = abs_time - last_time

track.append(Message('note_on', note=note, velocity=127, time=delta_time))

last_time = abs_time

if sample[y,x] >= thresh and (y == sample.shape[0]-1 or sample[y+1,x] < thresh):

delta_time = abs_time - last_time

track.append(Message('note_off', note=note, velocity=127, time=delta_time))

last_time = abs_time

mid.save(fname)