Zack Buhman
86d12c37ed
This adds both a midi generator and a midi type 1 simulator. While I would have preferred to use an existing tool for this, I found that timidity++ does not emit pitch wheel events correctly, and I don't know of another widely-distributed tool that does midi-to-midi format conversion. The c++ and python versions were co-developed. I wrote one to test the other. There is more cleanup to do, but `roundtrip.cpp` produces a valid type 0 midi file given a type 1 or type 0 midi file as input.
397 lines
9.9 KiB
Python
397 lines
9.9 KiB
Python
import struct
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from dataclasses import dataclass
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from typing import *
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import enum
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def parse_variable_length(buf):
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n = 0
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i = 0
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while i < 4:
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n <<= 7
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b = buf[i]
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i += 1
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n |= (b & 0x7f)
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if not b & 0x80:
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break
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else:
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assert False, bytes(buf[0:5])
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return buf[i:], n
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def parse_header_chunk_type(buf):
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assert buf[0] == ord('M'), bytes(buf[0:4])
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assert buf[1] == ord('T'), bytes(buf[0:4])
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assert buf[2] == ord('h'), bytes(buf[0:4])
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assert buf[3] == ord('d'), bytes(buf[0:4])
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return buf[4:], None
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def parse_uint32(buf):
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n, = struct.unpack('>L', buf[:4])
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return buf[4:], n
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def parse_uint16(buf):
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n, = struct.unpack('>H', buf[:2])
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return buf[2:], n
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@dataclass
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class MetricalDivision:
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ticks_per_quarter_note: int
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@dataclass
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class TimeCodeDivision:
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smpte: int
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ticks_per_frame: int
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@dataclass
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class Header:
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format: int
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ntrks: int
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division: Union[MetricalDivision, TimeCodeDivision]
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def parse_division(buf):
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buf, n = parse_uint16(buf)
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if n & (1 << 15):
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smpte = ((n >> 8) & 0x7f) - 0x80 # sign-extend
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ticks_per_frame = n & 0xff
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division = TimeCodeDivision(smpte, ticks_per_frame)
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else:
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ticks_per_quarter_note = n
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division = MetricalDivision(ticks_per_quarter_note)
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return buf, division
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def parse_header(buf):
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buf, _ = parse_header_chunk_type(buf)
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buf, length = parse_uint32(buf)
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assert length == 6, length
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buf, format = parse_uint16(buf)
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assert format in {0, 1, 2}, format
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buf, ntrks = parse_uint16(buf)
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buf, division = parse_division(buf)
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return buf, Header(format, ntrks, division)
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@dataclass
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class NoteOff:
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channel: int
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note: int
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velocity: int
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@dataclass
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class NoteOn:
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channel: int
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note: int
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velocity: int
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@dataclass
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class PolyphonicKeyPressure:
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channel: int
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note: int
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pressure: int
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control_change_description = dict([
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(0x00, "Bank Select"),
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(0x01, "Modulation wheel or lever"),
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(0x02, "Breath Controller"),
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(0x04, "Foot controller"),
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(0x05, "Portamento time"),
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(0x06, "Data entry MSB"),
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(0x07, "Channel Volume"),
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(0x08, "Balance"),
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(0x0A, "Pan"),
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(0x0B, "Expression Controller"),
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(0x0C, "Effect Control 1"),
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(0x0D, "Effect Control 2"),
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(0x10, "General Purpose Controller 1"),
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(0x11, "General Purpose Controller 2"),
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(0x12, "General Purpose Controller 3"),
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(0x13, "General Purpose Controller 4"),
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(0x40, "Damper pedal (sustain)"),
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(0x41, "Portamento On/Off"),
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(0x42, "Sostenuto"),
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(0x43, "Soft pedal"),
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(0x44, "Legato Footswitch (vv = 00-3F:Normal, 40-7F=Legatto)"),
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(0x45, "Hold 2"),
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(0x46, "Sound Controller 1 (default: Sound Variation)"),
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(0x47, "Sound Controller 2 (default: Timbre/Harmonic Intensity)"),
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(0x48, "Sound Controller 3 (default: Release Time)"),
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(0x49, "Sound Controller 4 (default: Attack Time)"),
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(0x4A, "Sound Controller 5 (default: Brightness)"),
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(0x4B, "Sound Controller 6 (default: no default)"),
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(0x4C, "Sound Controller 7 (default: no default)"),
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(0x4D, "Sound Controller 8 (default: no default)"),
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(0x4E, "Sound Controller 9 (default: no default)"),
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(0x4F, "Sound Controller 10 (default: no default)"),
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(0x50, "General Purpose Controller 5"),
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(0x51, "General Purpose Controller 6"),
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(0x52, "General Purpose Controller 7"),
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(0x53, "General Purpose Controller 9"),
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(0x54, "Portamento Control"),
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(0x5B, "Effects 1 Depth"),
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(0x5C, "Effects 2 Depth"),
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(0x5D, "Effects 3 Depth"),
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(0x5E, "Effects 4 Depth"),
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(0x5F, "Effects 5 Depth"),
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(0x60, "Data increment"),
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(0x61, "Data decrement"),
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(0x62, "Non-Registered Parameter Number LSB"),
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(0x63, "Non-Registered Parameter Number MSB"),
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(0x64, "Registered Parameter Number LSB"),
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(0x65, "Registered Parameter Number MSB"),
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])
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@dataclass
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class ControlChange:
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channel: int
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control: int
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value: int
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def __init__(self, channel, control, value):
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self.channel = channel
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self.control = (control, control_change_description.get(control, "Undefined"))
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self.value = value
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@dataclass
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class ProgramChange:
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channel: int
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program: int
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@dataclass
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class ChannelPressure:
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channel: int
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pressure: int
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@dataclass
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class PitchBendChange:
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channel: int
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lsb: int
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msb: int
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@dataclass
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class ChannelMode:
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channel: int
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controller: int
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value: int
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@dataclass
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class MIDIEvent:
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event: Union[
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NoteOff,
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NoteOn,
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PolyphonicKeyPressure,
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ControlChange,
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ProgramChange,
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ChannelPressure,
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PitchBendChange,
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ChannelMode,
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]
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@dataclass
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class SysexEvent:
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data: bytes
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class MetaType(enum.Enum):
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SequenceNumber = enum.auto()
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TextEvent = enum.auto()
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CopyrightNotice = enum.auto()
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SequenceTrackName = enum.auto()
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InstrumentName = enum.auto()
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Lyric = enum.auto()
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Marker = enum.auto()
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CuePoint = enum.auto()
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MIDIChannelPrefix = enum.auto()
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EndOfTrack = enum.auto()
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SetTempo = enum.auto()
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SMPTEOffset = enum.auto()
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TimeSignature = enum.auto()
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KeySignature = enum.auto()
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SequencerSpecific = enum.auto()
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def __repr__(self):
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return self.name
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def _sequence_number(b):
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assert len(b) == 2, b
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n, = struct.unpack('<H', b[:2])
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return n
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def _midi_channel_prefix(b):
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assert len(b) == 1, b
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return b[0]
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def _set_tempo(b):
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assert len(b) == 3, b
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n, = struct.unpack('<L', bytes([0, *b[:3]]))
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return n
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@dataclass
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class SMPTEOffsetValue:
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hr: int
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mn: int
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se: int
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fr: int
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ff: int
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def _smpte_offset(b):
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assert len(b) == 5, b
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return SMPTEOffsetValue(*b)
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@dataclass
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class TimeSignature:
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nn: int
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dd: int
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cc: int
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bb: int
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def _time_signature(b):
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assert len(b) == 4, b
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return TimeSignature(*b)
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@dataclass
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class KeySignature:
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sf: int
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mi: int
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def _key_signature(b):
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assert len(b) == 2
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return KeySignature(*b)
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def _bytes(b):
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return bytes(b)
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def _none(b):
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return None
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meta_nums = dict([
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(0x00, (MetaType.SequenceNumber, _sequence_number)),
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(0x01, (MetaType.TextEvent, _bytes)),
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(0x02, (MetaType.CopyrightNotice, _bytes)),
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(0x03, (MetaType.SequenceTrackName, _bytes)),
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(0x04, (MetaType.InstrumentName, _bytes)),
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(0x05, (MetaType.Lyric, _bytes)),
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(0x06, (MetaType.Marker, _bytes)),
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(0x07, (MetaType.CuePoint, _bytes)),
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(0x20, (MetaType.MIDIChannelPrefix, _midi_channel_prefix)),
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(0x2f, (MetaType.EndOfTrack, _none)),
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(0x51, (MetaType.SetTempo, _set_tempo)),
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(0x54, (MetaType.SMPTEOffset, _smpte_offset)),
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(0x58, (MetaType.TimeSignature, _time_signature)),
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(0x59, (MetaType.KeySignature, _key_signature)),
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(0x7f, (MetaType.SequencerSpecific, _bytes)),
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])
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@dataclass
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class MetaEvent:
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type: MetaType
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value: Any
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def parse_sysex_event(buf):
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if buf[0] not in {0xf0, 0xf7}:
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return None
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buf = buf[1:]
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buf, length = parse_variable_length(buf)
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data = buf[:length]
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buf = buf[length:]
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return buf, SysexEvent(bytes(data))
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def parse_meta_event(buf):
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if buf[0] != 0xff:
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return None
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type_n = buf[1]
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type, value_parser = meta_nums[type_n]
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#print(len(buf[2:]))
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buf, length = parse_variable_length(buf[2:])
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#print(len(buf[0:]))
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data = buf[:length]
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#print("meta", type_n, length, bytes(data))
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buf = buf[length:]
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return buf, MetaEvent(type, value_parser(data))
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midi_messages = dict([
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(0x80, (2, NoteOff)),
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(0x90, (2, NoteOn)),
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(0xa0, (2, PolyphonicKeyPressure)),
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(0xb0, (2, ControlChange)),
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(0xc0, (1, ProgramChange)),
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(0xd0, (1, ChannelPressure)),
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(0xe0, (2, PitchBendChange)),
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# ChannelMode handled specially
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])
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running_status = None
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def parse_midi_event(buf):
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global running_status
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if buf[0] & 0x80 == 0:
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assert running_status is not None, buf[0]
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else:
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running_status = buf[0]
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buf = buf[1:]
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message_type = running_status & 0xf0
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channel = running_status & 0x0f
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#assert message_type != 0xf0, hex(message_type)
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if message_type not in midi_messages:
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return None
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message_length, cls = midi_messages[message_type]
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data = buf[:message_length]
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# handle channel mode specially
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if cls is ControlChange and data[0] >= 121 and data[0] <= 127:
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# 0xb0 is overloaded for both control change and channel mode
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cls = ChannelMode
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message = MIDIEvent(cls(channel, *data))
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buf = buf[message_length:]
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return buf, message
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def parse_event(buf):
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if (midi := parse_midi_event(buf)) is not None:
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buf, midi = midi
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return buf, midi
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elif (sysex := parse_sysex_event(buf)) is not None:
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running_status = None
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buf, sysex = sysex
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return buf, sysex
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elif (meta := parse_meta_event(buf)) is not None:
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running_status = None
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buf, meta = meta
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return buf, meta
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else:
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assert False, ' '.join([hex(i)[2:] for i in buf[0:40]])
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return None
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@dataclass
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class Event:
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delta_time: int
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event: Union[MIDIEvent, SysexEvent, MetaEvent]
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def parse_mtrk_event(buf):
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buf, delta_time = parse_variable_length(buf)
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buf, event = parse_event(buf)
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return buf, Event(delta_time, event)
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def parse_track_chunk_type(buf):
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assert buf[0] == ord('M'), bytes(buf[0:4])
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assert buf[1] == ord('T'), bytes(buf[0:4])
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assert buf[2] == ord('r'), bytes(buf[0:4])
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assert buf[3] == ord('k'), bytes(buf[0:4])
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return buf[4:], None
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@dataclass
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class Track:
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events: list[Event]
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def parse_track(buf):
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head_buf = buf
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buf, _ = parse_track_chunk_type(buf)
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buf, length = parse_uint32(buf)
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offset = len(buf)
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events = []
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while (offset - len(buf)) < length:
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try:
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buf, event = parse_mtrk_event(buf)
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except:
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print('len', len(head_buf) - len(buf), length)
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raise
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events.append(event)
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return buf, Track(events)
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