Standard MIDI file, typically known just as "MID", is a standard way to serialize series of MIDI events, which is a protocol used in many music synthesizers to transfer music data: notes being played, effects being applied, etc.
Internally, file consists of a header and series of tracks, every track listing MIDI events with certain header designating time these events are happening.
NOTE: Rarely, MIDI files employ certain stateful compression scheme to avoid storing certain elements of further elements, instead reusing them from events which happened earlier in the stream. Kaitai Struct (as of v0.9) is currently unable to parse these, but files employing this mechanism are relatively rare.
This page hosts a formal specification of Standard MIDI file using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = StandardMidiFile.from_file("path/to/local/file.mid")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = StandardMidiFile(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.hdr # => get hdr
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import Enum
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 9):
raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))
import vlq_base128_be
class StandardMidiFile(KaitaiStruct):
"""Standard MIDI file, typically known just as "MID", is a standard way
to serialize series of MIDI events, which is a protocol used in many
music synthesizers to transfer music data: notes being played,
effects being applied, etc.
Internally, file consists of a header and series of tracks, every
track listing MIDI events with certain header designating time these
events are happening.
NOTE: Rarely, MIDI files employ certain stateful compression scheme
to avoid storing certain elements of further elements, instead
reusing them from events which happened earlier in the
stream. Kaitai Struct (as of v0.9) is currently unable to parse
these, but files employing this mechanism are relatively rare.
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.hdr = StandardMidiFile.Header(self._io, self, self._root)
self.tracks = []
for i in range(self.hdr.num_tracks):
self.tracks.append(StandardMidiFile.Track(self._io, self, self._root))
class TrackEvents(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.event = []
i = 0
while not self._io.is_eof():
self.event.append(StandardMidiFile.TrackEvent(self._io, self, self._root))
i += 1
class TrackEvent(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.v_time = vlq_base128_be.VlqBase128Be(self._io)
self.event_header = self._io.read_u1()
if self.event_header == 255:
self.meta_event_body = StandardMidiFile.MetaEventBody(self._io, self, self._root)
if self.event_header == 240:
self.sysex_body = StandardMidiFile.SysexEventBody(self._io, self, self._root)
_on = self.event_type
if _on == 224:
self.event_body = StandardMidiFile.PitchBendEvent(self._io, self, self._root)
elif _on == 144:
self.event_body = StandardMidiFile.NoteOnEvent(self._io, self, self._root)
elif _on == 208:
self.event_body = StandardMidiFile.ChannelPressureEvent(self._io, self, self._root)
elif _on == 192:
self.event_body = StandardMidiFile.ProgramChangeEvent(self._io, self, self._root)
elif _on == 160:
self.event_body = StandardMidiFile.PolyphonicPressureEvent(self._io, self, self._root)
elif _on == 176:
self.event_body = StandardMidiFile.ControllerEvent(self._io, self, self._root)
elif _on == 128:
self.event_body = StandardMidiFile.NoteOffEvent(self._io, self, self._root)
@property
def event_type(self):
if hasattr(self, '_m_event_type'):
return self._m_event_type
self._m_event_type = (self.event_header & 240)
return getattr(self, '_m_event_type', None)
@property
def channel(self):
if hasattr(self, '_m_channel'):
return self._m_channel
if self.event_type != 240:
self._m_channel = (self.event_header & 15)
return getattr(self, '_m_channel', None)
class PitchBendEvent(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.b1 = self._io.read_u1()
self.b2 = self._io.read_u1()
@property
def bend_value(self):
if hasattr(self, '_m_bend_value'):
return self._m_bend_value
self._m_bend_value = (((self.b2 << 7) + self.b1) - 16384)
return getattr(self, '_m_bend_value', None)
@property
def adj_bend_value(self):
if hasattr(self, '_m_adj_bend_value'):
return self._m_adj_bend_value
self._m_adj_bend_value = (self.bend_value - 16384)
return getattr(self, '_m_adj_bend_value', None)
class ProgramChangeEvent(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.program = self._io.read_u1()
class NoteOnEvent(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.note = self._io.read_u1()
self.velocity = self._io.read_u1()
class PolyphonicPressureEvent(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.note = self._io.read_u1()
self.pressure = self._io.read_u1()
class Track(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.magic = self._io.read_bytes(4)
if not self.magic == b"\x4D\x54\x72\x6B":
raise kaitaistruct.ValidationNotEqualError(b"\x4D\x54\x72\x6B", self.magic, self._io, u"/types/track/seq/0")
self.len_events = self._io.read_u4be()
self._raw_events = self._io.read_bytes(self.len_events)
_io__raw_events = KaitaiStream(BytesIO(self._raw_events))
self.events = StandardMidiFile.TrackEvents(_io__raw_events, self, self._root)
class MetaEventBody(KaitaiStruct):
class MetaTypeEnum(Enum):
sequence_number = 0
text_event = 1
copyright = 2
sequence_track_name = 3
instrument_name = 4
lyric_text = 5
marker_text = 6
cue_point = 7
midi_channel_prefix_assignment = 32
end_of_track = 47
tempo = 81
smpte_offset = 84
time_signature = 88
key_signature = 89
sequencer_specific_event = 127
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.meta_type = KaitaiStream.resolve_enum(StandardMidiFile.MetaEventBody.MetaTypeEnum, self._io.read_u1())
self.len = vlq_base128_be.VlqBase128Be(self._io)
self.body = self._io.read_bytes(self.len.value)
class ControllerEvent(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.controller = self._io.read_u1()
self.value = self._io.read_u1()
class Header(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.magic = self._io.read_bytes(4)
if not self.magic == b"\x4D\x54\x68\x64":
raise kaitaistruct.ValidationNotEqualError(b"\x4D\x54\x68\x64", self.magic, self._io, u"/types/header/seq/0")
self.len_header = self._io.read_u4be()
self.format = self._io.read_u2be()
self.num_tracks = self._io.read_u2be()
self.division = self._io.read_s2be()
class SysexEventBody(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.len = vlq_base128_be.VlqBase128Be(self._io)
self.data = self._io.read_bytes(self.len.value)
class NoteOffEvent(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.note = self._io.read_u1()
self.velocity = self._io.read_u1()
class ChannelPressureEvent(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.pressure = self._io.read_u1()