#!/usr/bin/python
# -*- coding: utf-8 -*-
# mingus - Music theory Python package, midi_file_in module.
# Copyright (C) 2008-2009, Bart Spaans
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""Read a MIDI file and convert it into mingus.containers objects."""
from mingus.containers.note import Note
from mingus.containers.note_container import NoteContainer
from mingus.containers.bar import Bar
from mingus.containers.track import Track
from mingus.containers.composition import Composition
from mingus.containers.instrument import MidiInstrument
import mingus.core.notes as notes
import mingus.core.intervals as intervals
import binascii
[docs]def MIDI_to_Composition(file):
"""Convert a MIDI file to a mingus.containers.Composition and return it
in a tuple with the last used tempo in beats per minute (this will
change in the future).
This function can raise all kinds of exceptions (IOError, HeaderError,
TimeDivisionError, FormatError), so be sure to try and catch.
"""
m = MidiFile()
return m.MIDI_to_Composition(file)
[docs]class TimeDivisionError(Exception):
pass
[docs]class MidiFile:
"""A class that parses a MIDI file."""
bpm = 120
meter = (4, 4)
bytes_read = 0
[docs] def MIDI_to_Composition(self, file):
(header, track_data) = self.parse_midi_file(file)
c = Composition()
if header[2]['fps']:
print "Don't know how to parse this yet"
return c
ticks_per_beat = header[2]['ticks_per_beat']
for track in track_data:
t = Track()
b = Bar()
metronome = 1 # Tick once every quarter note
thirtyseconds = 8 # 8 thirtyseconds in a quarter note
meter = (4, 4)
key = 'C'
for e in track:
(deltatime, event) = e
duration = float(deltatime) / (ticks_per_beat * 4.0)
if duration != 0.0:
duration = 1.0 / duration
if len(b.bar) > 0:
current_length = b.bar[-1][1]
b.bar[-1][1] = duration
if current_length - duration != 0:
b.current_beat -= 1.0 / current_length
b.current_beat += 1.0 / duration
if not b.place_notes(NoteContainer(), duration):
t + b
b = Bar(key, meter)
b.place_notes(NoteContainer(), duration)
if event['event'] == 8:
if deltatime == 0:
pass
elif event['event'] == 9:
# note on
n = Note(notes.int_to_note(event['param1'] % 12),
event['param1'] / 12 - 1)
n.channel = event['channel']
n.velocity = event['param2']
if len(b.bar) > 0:
b.bar[-1][2] + n
else:
b + n
elif event['event'] == 10:
# note aftertouch
pass
elif event['event'] == 11:
# controller select
pass
elif event['event'] == 12:
# program change
i = MidiInstrument()
i.instrument_nr = event['param1']
t.instrument = i
elif event['event'] == 0x0f:
# meta event Text
if event['meta_event'] == 1:
pass
elif event['meta_event'] == 3:
# Track name
t.name = event['data']
elif event['meta_event'] == 6:
# Marker
pass
elif event['meta_event'] == 7:
# Cue Point
pass
elif event['meta_event'] == 47:
# End of Track
pass
elif event['meta_event'] == 81:
# Set tempo warning Only the last change in bpm will get
# saved currently
mpqn = self.bytes_to_int(event['data'])
bpm = 60000000 / mpqn
elif event['meta_event'] == 88:
# Time Signature
d = event['data']
thirtyseconds = self.bytes_to_int(d[3])
metronome = self.bytes_to_int(d[2]) / 24.0
denom = 2 ** self.bytes_to_int(d[1])
numer = self.bytes_to_int(d[0])
meter = (numer, denom)
b.set_meter(meter)
elif event['meta_event'] == 89:
# Key Signature
d = event['data']
sharps = self.bytes_to_int(d[0])
minor = self.bytes_to_int(d[0])
if minor:
key = 'A'
else:
key = 'C'
for i in xrange(abs(sharps)):
if sharps < 0:
key = intervals.major_fourth(key)
else:
key = intervals.major_fifth(key)
b.key = Note(key)
else:
print 'Unsupported META event', event['meta_event']
else:
print 'Unsupported MIDI event', event
t + b
c.tracks.append(t)
return (c, bpm)
[docs] def bytes_to_int(self, bytes):
return int(binascii.b2a_hex(bytes), 16)
[docs] def parse_time_division(self, bytes):
"""Parse the time division found in the header of a MIDI file and
return a dictionary with the boolean fps set to indicate whether to
use frames per second or ticks per beat.
If fps is True, the values SMPTE_frames and clock_ticks will also be
set. If fps is False, ticks_per_beat will hold the value.
"""
# If highest bit is set, time division is set in frames per second
# otherwise in ticks_per_beat
value = self.bytes_to_int(bytes)
if not value & 0x8000:
return {'fps': False, 'ticks_per_beat': value & 0x7FFF}
else:
SMPTE_frames = (value & 0x7F00) >> 2
if SMPTE_frames not in [24, 25, 29, 30]:
raise TimeDivisionError, \
"'%d' is not a valid value for the number of SMPTE frames"\
% SMPTE_frames
clock_ticks = (value & 0x00FF) >> 2
return {'fps': True, 'SMPTE_frames': SMPTE_frames,
'clock_ticks': clock_ticks}
[docs] def parse_track(self, fp):
"""Parse a MIDI track from its header to its events.
Return a list of events and the number of bytes that were read.
"""
events = []
chunk_size = self.parse_track_header(fp)
bytes = chunk_size
while chunk_size > 0:
(delta_time, chunk_delta) = self.parse_varbyte_as_int(fp)
chunk_size -= chunk_delta
(event, chunk_delta) = self.parse_midi_event(fp)
chunk_size -= chunk_delta
events.append([delta_time, event])
if chunk_size < 0:
print 'yikes.', self.bytes_read, chunk_size
return events
[docs] def parse_midi_event(self, fp):
"""Parse a MIDI event.
Return a dictionary and the number of bytes read.
"""
chunk_size = 0
try:
ec = self.bytes_to_int(fp.read(1))
chunk_size += 1
self.bytes_read += 1
except:
raise IOError("Couldn't read event type "
"and channel data from file.")
# Get the nibbles
event_type = (ec & 0xf0) >> 4
channel = ec & 0x0f
# I don't know what these events are supposed to do, but I keep finding
# them. The parser ignores them.
if event_type < 8:
raise FormatError('Unknown event type %d. Byte %d.' % (event_type,
self.bytes_read))
# Meta events can have strings of variable length
if event_type == 0x0f:
try:
meta_event = self.bytes_to_int(fp.read(1))
(length, chunk_delta) = self.parse_varbyte_as_int(fp)
data = fp.read(length)
chunk_size += 1 + chunk_delta + length
self.bytes_read += 1 + length
except:
raise IOError("Couldn't read meta event from file.")
return ({'event': event_type, 'meta_event': meta_event,
'data': data}, chunk_size)
elif event_type in [12, 13]:
# Program change and Channel aftertouch events only have one
# parameter
try:
param1 = fp.read(1)
chunk_size += 1
self.bytes_read += 1
except:
raise IOError("Couldn't read MIDI event parameters from file.")
param1 = self.bytes_to_int(param1)
return ({'event': event_type, 'channel': channel,
'param1': param1}, chunk_size)
else:
try:
param1 = fp.read(1)
param2 = fp.read(1)
chunk_size += 2
self.bytes_read += 2
except:
raise IOError("Couldn't read MIDI event parameters from file.")
param1 = self.bytes_to_int(param1)
param2 = self.bytes_to_int(param2)
return ({'event': event_type, 'channel': channel, 'param1': param1,
'param2': param2}, chunk_size)
[docs] def parse_midi_file(self, file):
"""Parse a MIDI file.
Return the header -as a tuple containing respectively the MIDI
format, the number of tracks and the time division-, the parsed
track data and the number of bytes read.
"""
try:
f = open(file, 'r')
except:
raise IOError('File not found')
self.bytes_read = 0
header = self.parse_midi_file_header(f)
tracks = header[1]
result = []
while tracks > 0:
events = self.parse_track(f)
result.append(events)
tracks -= 1
f.close()
return (header, result)
[docs] def parse_varbyte_as_int(self, fp, return_bytes_read=True):
"""Read a variable length byte from the file and return the
corresponding integer."""
result = 0
bytes_read = 0
r = 0x80
while r & 0x80:
try:
r = self.bytes_to_int(fp.read(1))
self.bytes_read += 1
except:
raise IOError("Couldn't read variable length byte from file.")
if r & 0x80:
result = (result << 7) + (r & 0x7F)
else:
result = (result << 7) + r
bytes_read += 1
if not return_bytes_read:
return result
else:
return (result, bytes_read)
if __name__ == '__main__':
from sys import argv
import fluidsynth
import MidiFileOut
fluidsynth.init()
(m, bpm) = MIDI_to_Composition(argv[1])
MidiFileOut.write_Composition('test.mid', m, bpm)
