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Example of getting Bach from MusicXML using music21
"""
Example of iterating Bach Chorales and getting individual voice parts
In this case, want specifically 4 voice pieces only
Also transpose to key of C (major or minor depending on piece)
Also shows how to write out all the xml as midi
"""
# Author: Kyle Kastner
# License: BSD 3-Clause
# Based on StackOverflow answer
# http://stackoverflow.com/questions/36647054/music21-getting-all-notes-with-durations
# midi writing modified from tests inside music21
from music21 import corpus, interval, pitch
import time
import numpy as np
import os
def write_midi(pitch_block, duration_block, outfile="out.mid",
qpm_multiplier=1024, tempo_multiplier=1.0):
# Assumes any element with
from music21.midi import MidiTrack, MidiFile, MidiEvent, DeltaTime
# duration, pitch, velocity
qpm_mult = qpm_multiplier
all_mt = []
for i in range(pitch_block.shape[0]):
mt = MidiTrack(1)
t = 0
t_last = 0
pitch_slice = pitch_block[i, :]
duration_slice = duration_block[i, :]
beat_slice = list((qpm_mult * duration_slice).astype("int32"))
pitch_slice = list(pitch_slice.astype("int32"))
for d, p in zip(beat_slice, pitch_slice):
if (p == -1) or (d == -1):
# bypass
continue
dt = DeltaTime(mt)
dt.time = t - t_last
mt.events.append(dt)
me = MidiEvent(mt)
me.type = "NOTE_ON"
me.channel = 1
me.time = None
me.pitch = p
me.velocity = 90
mt.events.append(me)
# add note off / velocity zero message
dt = DeltaTime(mt)
dt.time = d
# add to track events
mt.events.append(dt)
me = MidiEvent(mt)
me.type = "NOTE_ON"
me.channel = 1
me.time = None
me.pitch = p
me.velocity = 0
mt.events.append(me)
t_last = t + d
t += d
# add end of track
dt = DeltaTime(mt)
dt.time = 0
mt.events.append(dt)
me = MidiEvent(mt)
me.type = "END_OF_TRACK"
me.channel = 1
me.data = ''
mt.events.append(me)
all_mt.append(mt)
mf = MidiFile()
mf.ticksPerQuarterNote = int(tempo_multiplier * qpm_mult)
for mt in all_mt:
mf.tracks.append(mt)
mf.open(outfile, 'wb')
mf.write()
mf.close()
start = time.time()
all_bach_paths = corpus.getComposer('bach')
print("Total number of Bach pieces to process from music21: %i" % len(all_bach_paths))
skipped = 0
processed = 0
n_major = 0
n_minor = 0
all_major = []
all_minor = []
for it, p_bach in enumerate(all_bach_paths):
if "riemenschneider" in p_bach:
# skip certain files we don't care about
skipped += 1
continue
p = corpus.parse(p_bach)
if len(p.parts) != 4:
print("Skipping file %i, %s due to undesired voice count..." % (it, p_bach))
skipped += 1
continue
print("Processing %i, %s ..." % (it, p_bach))
k = p.analyze('key')
print("Original key: %s" % k)
i = interval.Interval(k.tonic, pitch.Pitch('C'))
p = p.transpose(i)
k = p.analyze('key')
print("Transposed key: %s" % k)
if 'major' in k.name:
n_major += 1
elif 'minor' in k.name:
n_minor += 1
else:
raise ValueError('Unknown key %s' % k.name)
try:
parts = []
parts_times = []
for i, pi in enumerate(p.parts):
part = []
part_time = []
for n in pi.stream().flat.notesAndRests:
if n.isRest:
part.append(0)
else:
part.append(n.midi)
part_time.append(n.duration.quarterLength)
parts.append(part)
parts_times.append(part_time)
# Create a "block" of events and times
cumulative_times = map(lambda x: list(np.cumsum(x)), parts_times)
event_points = sorted(list(set(sum(cumulative_times, []))))
maxlen = max(map(len, cumulative_times))
# -1 marks invalid / unused
part_block = np.zeros((len(p.parts), maxlen)).astype("int32") - 1
ctime_block = np.zeros((len(p.parts), maxlen)).astype("float32") - 1
time_block = np.zeros((len(p.parts), maxlen)).astype("float32") - 1
# create numpy array for easier indexing
for i in range(len(parts)):
part_block[i, :len(parts[i])] = parts[i]
ctime_block[i, :len(cumulative_times[i])] = cumulative_times[i]
time_block[i, :len(parts_times[i])] = parts_times[i]
event_block = np.zeros((len(p.parts), len(event_points))) - 1
etime_block = np.zeros((len(p.parts), len(event_points))) - 1
for i, e in enumerate(event_points):
idx = zip(*np.where(ctime_block == e))
for ix in idx:
event_block[ix[0], i] = part_block[ix[0], ix[1]]
etime_block[ix[0], i] = time_block[ix[0], ix[1]]
bach_name = "_".join(p_bach.split(os.sep)[-1].split(".")[:-1])
midi_outfile = bach_name + ".mid"
write_midi(event_block, etime_block,
outfile="midifiles/" + midi_outfile,
tempo_multiplier=1.0)
# Grouping
processed += 1
except AttributeError:
skipped += 1
# Edge case for Chord error? Should be flat container but some piece is different
continue
stop = time.time()
print("Total skipped count: %i" % skipped)
print("Total processed count: %i" % processed)
print("Total major: %i" % n_major)
print("Total minor: %i" % n_minor)
print("Total processing time (seconds): %f" % (stop - start))
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