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# Python midifile package -- parse, load and play MIDI files.
# Copyright (c) 2011 - 2014 by Wilbert Berendsen
#
# 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 2
# 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, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
# See http://www.gnu.org/licenses/ for more information.
"""
midifile.parser -- parses MIDI file data.
This is a simple module that can parse data from a MIDI file and
its tracks.
A basic event factory returns the MIDI events as simple named tuples,
but you can subclass the event factory for more sophisticated behaviour.
Runs with Python 2.6, 2.7 and 3.
"""
from __future__ import print_function
import sys
import struct
from . import event
PY2 = sys.version_info[0] == 2
unpack_midi_header = struct.Struct(b'>hhh').unpack
unpack_int = struct.Struct(b'>i').unpack
def get_chunks(s):
"""Splits a MIDI file bytes string into chunks.
Yields (b'Name', b'data') tuples.
"""
pos = 0
while pos < len(s):
name = s[pos:pos+4]
size, = unpack_int(s[pos+4:pos+8])
yield name, s[pos+8:pos+8+size]
pos += size + 8
def parse_midi_data(s):
"""Parses MIDI file data from the bytes string s.
Returns a three tuple (format_type, time_division, tracks).
Every track is an unparsed bytes string.
May raise ValueError or IndexError in case of invalid MIDI data.
"""
chunks = get_chunks(s)
for name, data in chunks:
if name == b'MThd':
fmt, ntracks, division = unpack_midi_header(data[:6])
tracks = [data for name, data in chunks if name == b'MTrk']
return fmt, division, tracks
break
raise ValueError("invalid midi data")
def read_var_len(s, pos):
"""Reads variable-length integer from byte string s starting on pos.
Returns the value and the new position.
"""
value = 0
while True:
i = s[pos]
pos += 1
value = value * 128 + (i & 0x7F)
if not i & 0x80:
return value, pos
def parse_midi_events(s, factory=None):
"""Parses the bytes string s (typically a track) for MIDI events.
If factory is given, it should be an EventFactory instance that
returns objects describing the event.
Yields two-tuples (delta, event).
Raises ValueError or IndexError on invalid MIDI data.
"""
if factory is None:
factory = event.EventFactory()
running_status = None
if PY2:
s = bytearray(s)
pos = 0
while pos < len(s):
delta, pos = read_var_len(s, pos)
status = s[pos]
if status & 0x80:
running_status = status
pos += 1
elif not running_status:
raise ValueError("invalid running status")
else:
status = running_status
ev_type = status >> 4
channel = status & 0x0F
if ev_type <= 0x0A:
# note on, off or aftertouch
note = s[pos]
value = s[pos+1]
pos += 2
ev = factory.note_event(ev_type, channel, note, value)
elif ev_type >= 0x0F:
running_status = None
if status == 0xFF:
# meta event
meta_type = s[pos]
meta_size, pos = read_var_len(s, pos+1)
meta_data = s[pos:pos+meta_size]
pos += meta_size
ev = factory.meta_event(meta_type, meta_data)
else:
# some sort of sysex
sysex_size, pos = read_var_len(s, pos)
sysex_data = s[pos:pos+sysex_size]
pos += sysex_size
ev = factory.sysex_event(status, sysex_data)
elif ev_type == 0x0E:
# Pitch Bend
value = s[pos] + s[pos+1] * 128
pos += 2
ev = factory.pitchbend_event(channel, value)
elif ev_type == 0xD:
# Channel AfterTouch
value = s[pos]
pos += 1
ev = factory.channelaftertouch_event(channel, value)
elif ev_type == 0xB:
# Controller
number = s[pos]
value = s[pos+1]
pos += 2
ev = factory.controller_event(channel, number, value)
else: # ev_type == 0xC
# Program Change
number = s[pos]
pos += 1
ev = factory.programchange_event(channel, number)
yield delta, ev
def time_events(track, time=0):
"""Yields two-tuples (time, event).
The track is the generator returned by parse_midi_events,
the time is accumulated from the given starting time (defaulting to 0).
"""
for delta, ev in track:
time += delta
yield time, ev
def time_events_grouped(track, time=0):
"""Yields two-tuples (time, event_list).
Every event_list is a Python list of all events happening on that time.
The track is the generator returned by parse_midi_events,
the time is accumulated from the given starting time (defaulting to 0).
"""
evs = []
for delta, ev in track:
if delta:
if evs:
yield time, evs
evs = []
time += delta
evs.append(ev)
if evs:
yield time, evs
if __name__ == '__main__':
"""Test specified MIDI files."""
import sys
files = sys.argv[1:]
for f in files:
with open(f, 'rb') as midifile:
s = midifile.read()
ftm, div, tracks = parse_midi_data(s)
try:
for t in tracks:
print(list(parse_midi_events(t)))
except Exception as e:
print('error in:', f)
print(e)
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