# Copyright 2023 The Magenta Authors. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """MIDI ops. Input and output wrappers for converting between MIDI and other formats. """ import collections import io import sys from note_seq import constants from note_seq.protobuf import music_pb2 import pretty_midi # Allow pretty_midi to read MIDI files with absurdly high tick rates. # Useful for reading the MAPS dataset. # https://github.com/craffel/pretty-midi/issues/112 pretty_midi.pretty_midi.MAX_TICK = 1e10 # The offset used to change the mode of a key from major to minor when # generating a PrettyMIDI KeySignature. _PRETTY_MIDI_MAJOR_TO_MINOR_OFFSET = 12 class MIDIConversionError(Exception): pass def midi_to_note_sequence(midi_data): """Convert MIDI file contents to a NoteSequence. Converts a MIDI file encoded as a string into a NoteSequence. Decoding errors are very common when working with large sets of MIDI files, so be sure to handle MIDIConversionError exceptions. Args: midi_data: A string containing the contents of a MIDI file or populated pretty_midi.PrettyMIDI object. Returns: A NoteSequence. Raises: MIDIConversionError: An improper MIDI mode was supplied. """ # In practice many MIDI files cannot be decoded with pretty_midi. Catch all # errors here and try to log a meaningful message. So many different # exceptions are raised in pretty_midi.PrettyMidi that it is cumbersome to # catch them all only for the purpose of error logging. # pylint: disable=bare-except if isinstance(midi_data, pretty_midi.PrettyMIDI): midi = midi_data else: try: midi = pretty_midi.PrettyMIDI(io.BytesIO(midi_data)) except: raise MIDIConversionError('Midi decoding error %s: %s' % (sys.exc_info()[0], sys.exc_info()[1])) # pylint: enable=bare-except sequence = music_pb2.NoteSequence() # Populate header. sequence.ticks_per_quarter = midi.resolution sequence.source_info.parser = music_pb2.NoteSequence.SourceInfo.PRETTY_MIDI sequence.source_info.encoding_type = ( music_pb2.NoteSequence.SourceInfo.MIDI) # Populate time signatures. for midi_time in midi.time_signature_changes: time_signature = sequence.time_signatures.add() time_signature.time = midi_time.time time_signature.numerator = midi_time.numerator try: # Denominator can be too large for int32. time_signature.denominator = midi_time.denominator except ValueError: raise MIDIConversionError('Invalid time signature denominator %d' % midi_time.denominator) # Populate key signatures. for midi_key in midi.key_signature_changes: key_signature = sequence.key_signatures.add() key_signature.time = midi_key.time key_signature.key = midi_key.key_number % 12 midi_mode = midi_key.key_number // 12 if midi_mode == 0: key_signature.mode = key_signature.MAJOR elif midi_mode == 1: key_signature.mode = key_signature.MINOR else: raise MIDIConversionError('Invalid midi_mode %i' % midi_mode) # Populate tempo changes. tempo_times, tempo_qpms = midi.get_tempo_changes() for time_in_seconds, tempo_in_qpm in zip(tempo_times, tempo_qpms): tempo = sequence.tempos.add() tempo.time = time_in_seconds tempo.qpm = tempo_in_qpm # Populate notes by gathering them all from the midi's instruments. # Also set the sequence.total_time as the max end time in the notes. midi_notes = [] midi_pitch_bends = [] midi_control_changes = [] for num_instrument, midi_instrument in enumerate(midi.instruments): # Populate instrument name from the midi's instruments if midi_instrument.name: instrument_info = sequence.instrument_infos.add() instrument_info.name = midi_instrument.name instrument_info.instrument = num_instrument for midi_note in midi_instrument.notes: if not sequence.total_time or midi_note.end > sequence.total_time: sequence.total_time = midi_note.end midi_notes.append((midi_instrument.program, num_instrument, midi_instrument.is_drum, midi_note)) for midi_pitch_bend in midi_instrument.pitch_bends: midi_pitch_bends.append( (midi_instrument.program, num_instrument, midi_instrument.is_drum, midi_pitch_bend)) for midi_control_change in midi_instrument.control_changes: midi_control_changes.append( (midi_instrument.program, num_instrument, midi_instrument.is_drum, midi_control_change)) for program, instrument, is_drum, midi_note in midi_notes: note = sequence.notes.add() note.instrument = instrument note.program = program note.start_time = midi_note.start note.end_time = midi_note.end note.pitch = midi_note.pitch note.velocity = midi_note.velocity note.is_drum = is_drum for program, instrument, is_drum, midi_pitch_bend in midi_pitch_bends: pitch_bend = sequence.pitch_bends.add() pitch_bend.instrument = instrument pitch_bend.program = program pitch_bend.time = midi_pitch_bend.time pitch_bend.bend = midi_pitch_bend.pitch pitch_bend.is_drum = is_drum for program, instrument, is_drum, midi_control_change in midi_control_changes: control_change = sequence.control_changes.add() control_change.instrument = instrument control_change.program = program control_change.time = midi_control_change.time control_change.control_number = midi_control_change.number control_change.control_value = midi_control_change.value control_change.is_drum = is_drum # TODO(douglaseck): Estimate note type (e.g. quarter note) and populate # note.numerator and note.denominator. return sequence def midi_file_to_note_sequence(midi_file): """Converts MIDI file to a NoteSequence. Args: midi_file: A string path to a MIDI file. Returns: A NoteSequence. Raises: MIDIConversionError: Invalid midi_file. """ with open(midi_file, 'rb') as f: midi_as_string = f.read() return midi_to_note_sequence(midi_as_string) def note_sequence_to_midi_file(sequence, output_file, drop_events_n_seconds_after_last_note=None): """Convert NoteSequence to a MIDI file on disk. Time is stored in the NoteSequence in absolute values (seconds) as opposed to relative values (MIDI ticks). When the NoteSequence is translated back to MIDI the absolute time is retained. The tempo map is also recreated. Args: sequence: A NoteSequence. output_file: String path to MIDI file that will be written. drop_events_n_seconds_after_last_note: Events (e.g., time signature changes) that occur this many seconds after the last note will be dropped. If None, then no events will be dropped. """ pretty_midi_object = note_sequence_to_pretty_midi( sequence, drop_events_n_seconds_after_last_note) pretty_midi_object.write(open(output_file, 'wb')) def note_sequence_to_pretty_midi( sequence, drop_events_n_seconds_after_last_note=None): """Convert NoteSequence to a PrettyMIDI. Time is stored in the NoteSequence in absolute values (seconds) as opposed to relative values (MIDI ticks). When the NoteSequence is translated back to PrettyMIDI the absolute time is retained. The tempo map is also recreated. Args: sequence: A NoteSequence. drop_events_n_seconds_after_last_note: Events (e.g., time signature changes) that occur this many seconds after the last note will be dropped. If None, then no events will be dropped. Returns: A pretty_midi.PrettyMIDI object or None if sequence could not be decoded. """ ticks_per_quarter = sequence.ticks_per_quarter or constants.STANDARD_PPQ max_event_time = None if drop_events_n_seconds_after_last_note is not None: max_event_time = (max([n.end_time for n in sequence.notes] or [0]) + drop_events_n_seconds_after_last_note) # Try to find a tempo at time zero. The list is not guaranteed to be in order. initial_seq_tempo = None for seq_tempo in sequence.tempos: if seq_tempo.time == 0: initial_seq_tempo = seq_tempo break kwargs = {} if initial_seq_tempo: kwargs['initial_tempo'] = initial_seq_tempo.qpm else: kwargs['initial_tempo'] = constants.DEFAULT_QUARTERS_PER_MINUTE pm = pretty_midi.PrettyMIDI(resolution=ticks_per_quarter, **kwargs) # Create an empty instrument to contain time and key signatures. instrument = pretty_midi.Instrument(0) pm.instruments.append(instrument) # Populate time signatures. for seq_ts in sequence.time_signatures: if max_event_time and seq_ts.time > max_event_time: continue time_signature = pretty_midi.containers.TimeSignature( seq_ts.numerator, seq_ts.denominator, seq_ts.time) pm.time_signature_changes.append(time_signature) # Populate key signatures. for seq_key in sequence.key_signatures: if max_event_time and seq_key.time > max_event_time: continue key_number = seq_key.key if seq_key.mode == seq_key.MINOR: key_number += _PRETTY_MIDI_MAJOR_TO_MINOR_OFFSET key_signature = pretty_midi.containers.KeySignature( key_number, seq_key.time) pm.key_signature_changes.append(key_signature) # Populate tempos. # TODO(douglaseck): Update this code if pretty_midi adds the ability to # write tempo. for seq_tempo in sequence.tempos: # Skip if this tempo was added in the PrettyMIDI constructor. if seq_tempo == initial_seq_tempo: continue if max_event_time and seq_tempo.time > max_event_time: continue tick_scale = 60.0 / (pm.resolution * seq_tempo.qpm) tick = pm.time_to_tick(seq_tempo.time) # pylint: disable=protected-access pm._tick_scales.append((tick, tick_scale)) pm._update_tick_to_time(0) # pylint: enable=protected-access # Populate instrument names by first creating an instrument map between # instrument index and name. # Then, going over this map in the instrument event for loop inst_infos = {} for inst_info in sequence.instrument_infos: inst_infos[inst_info.instrument] = inst_info.name # Populate instrument events by first gathering notes and other event types # in lists then write them sorted to the PrettyMidi object. instrument_events = collections.defaultdict( lambda: collections.defaultdict(list)) for seq_note in sequence.notes: instrument_events[(seq_note.instrument, seq_note.program, seq_note.is_drum)]['notes'].append( pretty_midi.Note( seq_note.velocity, seq_note.pitch, seq_note.start_time, seq_note.end_time)) for seq_bend in sequence.pitch_bends: if max_event_time and seq_bend.time > max_event_time: continue instrument_events[(seq_bend.instrument, seq_bend.program, seq_bend.is_drum)]['bends'].append( pretty_midi.PitchBend(seq_bend.bend, seq_bend.time)) for seq_cc in sequence.control_changes: if max_event_time and seq_cc.time > max_event_time: continue instrument_events[(seq_cc.instrument, seq_cc.program, seq_cc.is_drum)]['controls'].append( pretty_midi.ControlChange( seq_cc.control_number, seq_cc.control_value, seq_cc.time)) for (instr_id, prog_id, is_drum) in sorted(instrument_events.keys()): # For instr_id 0 append to the instrument created above. if instr_id > 0: if is_drum: name = 'Drums' else: name = pretty_midi.program_to_instrument_name(prog_id) instrument = pretty_midi.Instrument(prog_id, is_drum, name) pm.instruments.append(instrument) else: instrument.is_drum = is_drum # propagate instrument name to the midi file instrument.program = prog_id if instr_id in inst_infos: instrument.name = inst_infos[instr_id] instrument.notes = instrument_events[ (instr_id, prog_id, is_drum)]['notes'] instrument.pitch_bends = instrument_events[ (instr_id, prog_id, is_drum)]['bends'] instrument.control_changes = instrument_events[ (instr_id, prog_id, is_drum)]['controls'] return pm def midi_to_sequence_proto(midi_data): """Renamed to midi_to_note_sequence.""" return midi_to_note_sequence(midi_data) def sequence_proto_to_pretty_midi(sequence, drop_events_n_seconds_after_last_note=None): """Renamed to note_sequence_to_pretty_midi.""" return note_sequence_to_pretty_midi(sequence, drop_events_n_seconds_after_last_note) def midi_file_to_sequence_proto(midi_file): """Renamed to midi_file_to_note_sequence.""" return midi_file_to_note_sequence(midi_file) def sequence_proto_to_midi_file(sequence, output_file, drop_events_n_seconds_after_last_note=None): """Renamed to note_sequence_to_midi_file.""" return note_sequence_to_midi_file(sequence, output_file, drop_events_n_seconds_after_last_note)