midi_tokenizer.py

import random
from typing import Dict, Any

import PIL.Image
import numpy as np


class MIDITokenizerV1:
 def __init__(self):
 self.version = "v1"
 self.optimise_midi = False
 self.vocab_size = 0

 def allocate_ids(size):
 ids = [self.vocab_size + i for i in range(size)]
 self.vocab_size += size
 return ids

 self.pad_id = allocate_ids(1)[0]
 self.bos_id = allocate_ids(1)[0]
 self.eos_id = allocate_ids(1)[0]
 self.events = {
 "note": ["time1", "time2", "track", "duration", "channel", "pitch", "velocity"],
 "patch_change": ["time1", "time2", "track", "channel", "patch"],
 "control_change": ["time1", "time2", "track", "channel", "controller", "value"],
 "set_tempo": ["time1", "time2", "track", "bpm"],
 }
 self.event_parameters = {
 "time1": 128, "time2": 16, "duration": 2048, "track": 128, "channel": 16, "pitch": 128, "velocity": 128,
 "patch": 128, "controller": 128, "value": 128, "bpm": 256
 }
 self.event_ids = {e: allocate_ids(1)[0] for e in self.events.keys()}
 self.id_events = {i: e for e, i in self.event_ids.items()}
 self.parameter_ids = {p: allocate_ids(s) for p, s in self.event_parameters.items()}
 self.max_token_seq = max([len(ps) for ps in self.events.values()]) + 1

 def to_dict(self) -> Dict[str, Any]:
 d = {
 "version":self.version,
 "optimise_midi":self.optimise_midi,
 "vocab_size": self.vocab_size,
 "events": self.events,
 "event_parameters": self.event_parameters,
 "max_token_seq": self.max_token_seq,
 "pad_id": self.pad_id,
 "bos_id": self.bos_id,
 "eos_id": self.eos_id,
 }
 return d

 def set_optimise_midi(self, optimise_midi=True):
 self.optimise_midi = optimise_midi

 @staticmethod
 def tempo2bpm(tempo):
 tempo = tempo / 10 ** 6 # us to s
 bpm = 60 / tempo
 return bpm

 @staticmethod
 def bpm2tempo(bpm):
 if bpm == 0:
 bpm = 1
 tempo = int((60 / bpm) * 10 ** 6)
 return tempo

 def tokenize(self, midi_score, add_bos_eos=True, cc_eps=4, tempo_eps=4,
 remap_track_channel=None, add_default_instr=None, remove_empty_channels=None):
 if remap_track_channel is None: # set default value
 remap_track_channel = self.optimise_midi
 if add_default_instr is None:
 add_default_instr = self.optimise_midi
 if remove_empty_channels is None:
 remove_empty_channels = self.optimise_midi

 ticks_per_beat = midi_score[0]
 event_list = {}
 track_idx_map = {i: dict() for i in range(16)}
 track_idx_dict = {}
 channels = []
 patch_channels = []
 empty_channels = [True] * 16
 channel_note_tracks = {i: list() for i in range(16)}
 for track_idx, track in enumerate(midi_score[1:129]):
 last_notes = {}
 patch_dict = {}
 control_dict = {}
 last_tempo = 0
 for event in track:
 if event[0] not in self.events:
 continue
 c = -1
 t = round(16 * event[1] / ticks_per_beat) # quantization
 new_event = [event[0], t // 16, t % 16, track_idx] + event[2:]
 if event[0] == "note":
 c = event[3]
 if c > 15 or c < 0:
 continue
 empty_channels[c] = False
 track_idx_dict.setdefault(c, track_idx)
 note_tracks = channel_note_tracks[c]
 if track_idx not in note_tracks:
 note_tracks.append(track_idx)
 new_event[4] = max(1, round(16 * new_event[4] / ticks_per_beat))
 elif event[0] == "set_tempo":
 if new_event[4] == 0: # invalid tempo
 continue
 bpm = int(self.tempo2bpm(new_event[4]))
 new_event[4] = min(bpm, 255)
 if event[0] == "note":
 key = tuple(new_event[:4] + new_event[5:-1])
 else:
 key = tuple(new_event[:-1])
 if event[0] == "patch_change":
 c, p = event[2:]
 if c > 15 or c < 0:
 continue
 last_p = patch_dict.setdefault(c, None)
 if last_p == p:
 continue
 patch_dict[c] = p
 if c not in patch_channels:
 patch_channels.append(c)
 elif event[0] == "control_change":
 c, cc, v = event[2:]
 if c > 15 or c < 0:
 continue
 last_v = control_dict.setdefault((c, cc), 0)
 if abs(last_v - v) < cc_eps:
 continue
 control_dict[(c, cc)] = v
 elif event[0] == "set_tempo":
 tempo = new_event[-1]
 if abs(last_tempo - tempo) < tempo_eps:
 continue
 last_tempo = tempo

 if c != -1:
 if c not in channels:
 channels.append(c)
 tr_map = track_idx_map[c]
 if track_idx not in tr_map:
 tr_map[track_idx] = 0

 if event[0] == "note": # to eliminate note overlap due to quantization
 cp = tuple(new_event[5:7])
 if cp in last_notes:
 last_note_key, last_note = last_notes[cp]
 last_t = last_note[1] * 16 + last_note[2]
 last_note[4] = max(0, min(last_note[4], t - last_t))
 if last_note[4] == 0:
 event_list.pop(last_note_key)
 last_notes[cp] = (key, new_event)
 event_list[key] = new_event
 event_list = list(event_list.values())

 empty_channels = [c for c in channels if empty_channels[c]]

 if remap_track_channel:
 patch_channels = []
 channels_count = 0
 channels_map = {9: 9} if 9 in channels else {}
 if remove_empty_channels:
 channels = sorted(channels, key=lambda x: 1 if x in empty_channels else 0)
 for c in channels:
 if c == 9:
 continue
 channels_map[c] = channels_count
 channels_count += 1
 if channels_count == 9:
 channels_count = 10
 channels = list(channels_map.values())

 track_count = 0
 track_idx_map_order = [k for k, v in sorted(list(channels_map.items()), key=lambda x: x[1])]
 for c in track_idx_map_order: # tracks not to remove
 if remove_empty_channels and c in empty_channels:
 continue
 tr_map = track_idx_map[c]
 for track_idx in tr_map:
 note_tracks = channel_note_tracks[c]
 if len(note_tracks) != 0 and track_idx not in note_tracks:
 continue
 track_count += 1
 tr_map[track_idx] = track_count
 for c in track_idx_map_order: # tracks to remove
 if not (remove_empty_channels and c in empty_channels):
 continue
 tr_map = track_idx_map[c]
 for track_idx in tr_map:
 note_tracks = channel_note_tracks[c]
 if not (len(note_tracks) != 0 and track_idx not in note_tracks):
 continue
 track_count += 1
 tr_map[track_idx] = track_count

 empty_channels = [channels_map[c] for c in empty_channels]
 track_idx_dict = {}
 for event in event_list:
 name = event[0]
 track_idx = event[3]
 if name == "note":
 c = event[5]
 event[5] = channels_map[c]
 event[3] = track_idx_map[c][track_idx]
 track_idx_dict.setdefault(event[5], event[3])
 # setdefault, so the track_idx is first of the channel
 elif name == "set_tempo":
 event[3] = 0
 elif name == "control_change" or name == "patch_change":
 c = event[4]
 event[4] = channels_map[c]
 tr_map = track_idx_map[c]
 # move the event to first track of the channel if it's original track is empty
 note_tracks = channel_note_tracks[c]
 if len(note_tracks) != 0 and track_idx not in note_tracks:
 track_idx = channel_note_tracks[c][0]
 new_track_idx = tr_map[track_idx]
 event[3] = new_track_idx
 if name == "patch_change" and event[4] not in patch_channels:
 patch_channels.append(event[4])

 if add_default_instr:
 for c in channels:
 if c not in patch_channels and c in track_idx_dict:
 event_list.append(["patch_change", 0, 0, track_idx_dict[c], c, 0])

 events_name_order = {"set_tempo": 0, "patch_change": 1, "control_change": 2, "note": 3}
 events_order = lambda e: e[1:4] + [events_name_order[e[0]]]
 event_list = sorted(event_list, key=events_order)

 setup_events = {}
 notes_in_setup = False
 for i, event in enumerate(event_list): # optimise setup
 new_event = [*event]
 if event[0] != "note":
 new_event[1] = 0
 new_event[2] = 0
 has_next = False
 has_pre = False
 if i < len(event_list) - 1:
 next_event = event_list[i + 1]
 has_next = event[1] + event[2] == next_event[1] + next_event[2]
 if notes_in_setup and i > 0:
 pre_event = event_list[i - 1]
 has_pre = event[1] + event[2] == pre_event[1] + pre_event[2]
 if (event[0] == "note" and not has_next) or (notes_in_setup and not has_pre):
 event_list = sorted(setup_events.values(), key=events_order) + event_list[i:]
 break
 else:
 if event[0] == "note":
 notes_in_setup = True
 key = tuple([event[0]] + event[3:-2])
 else:
 key = tuple([event[0]] + event[3:-1])
 setup_events[key] = new_event

 last_t1 = 0
 midi_seq = []
 for event in event_list:
 if remove_empty_channels and event[0] in ["control_change", "patch_change"] and event[4] in empty_channels:
 continue
 cur_t1 = event[1]
 event[1] = event[1] - last_t1
 tokens = self.event2tokens(event)
 if not tokens:
 continue
 midi_seq.append(tokens)
 last_t1 = cur_t1

 if add_bos_eos:
 bos = [self.bos_id] + [self.pad_id] * (self.max_token_seq - 1)
 eos = [self.eos_id] + [self.pad_id] * (self.max_token_seq - 1)
 midi_seq = [bos] + midi_seq + [eos]
 return midi_seq

 def event2tokens(self, event):
 name = event[0]
 params = event[1:]
 if not all([0 <= params[i] < self.event_parameters[p] for i, p in enumerate(self.events[name])]):
 return []
 tokens = [self.event_ids[name]] + [self.parameter_ids[p][params[i]]
 for i, p in enumerate(self.events[name])]
 tokens += [self.pad_id] * (self.max_token_seq - len(tokens))
 return tokens

 def tokens2event(self, tokens):
 if tokens[0] not in self.id_events:
 return []
 name = self.id_events[tokens[0]]
 if len(tokens) <= len(self.events[name]):
 return []
 params = tokens[1:]
 params = [params[i] - self.parameter_ids[p][0] for i, p in enumerate(self.events[name])]
 if not all([0 <= params[i] < self.event_parameters[p] for i, p in enumerate(self.events[name])]):
 return []
 event = [name] + params
 return event

 def detokenize(self, midi_seq):
 ticks_per_beat = 480
 tracks_dict = {}
 t1 = 0
 for tokens in midi_seq:
 if tokens[0] in self.id_events:
 event = self.tokens2event(tokens)
 if not event:
 continue
 name = event[0]
 if name == "set_tempo":
 event[4] = self.bpm2tempo(event[4])
 if event[0] == "note":
 event[4] = int(event[4] * ticks_per_beat / 16)
 t1 += event[1]
 t = t1 * 16 + event[2]
 t = int(t * ticks_per_beat / 16)
 track_idx = event[3]
 if track_idx not in tracks_dict:
 tracks_dict[track_idx] = []
 tracks_dict[track_idx].append([event[0], t] + event[4:])
 tracks = [tr for idx, tr in sorted(list(tracks_dict.items()), key=lambda it: it[0])]

 for i in range(len(tracks)): # to eliminate note overlap
 track = tracks[i]
 track = sorted(track, key=lambda e: e[1])
 last_note_t = {}
 zero_len_notes = []
 for e in reversed(track):
 if e[0] == "note":
 t, d, c, p = e[1:5]
 key = (c, p)
 if key in last_note_t:
 d = min(d, max(last_note_t[key] - t, 0))
 last_note_t[key] = t
 e[2] = d
 if d == 0:
 zero_len_notes.append(e)
 for e in zero_len_notes:
 track.remove(e)
 tracks[i] = track
 return [ticks_per_beat, *tracks]

 def midi2img(self, midi_score):
 ticks_per_beat = midi_score[0]
 notes = []
 max_time = 1
 track_num = len(midi_score[1:])
 for track_idx, track in enumerate(midi_score[1:]):
 for event in track:
 t = round(16 * event[1] / ticks_per_beat)
 if event[0] == "note":
 d = max(1, round(16 * event[2] / ticks_per_beat))
 c, p = event[3:5]
 max_time = max(max_time, t + d + 1)
 notes.append((track_idx, c, p, t, d))
 img = np.zeros((128, max_time, 3), dtype=np.uint8)
 colors = {(i, j): np.random.randint(50, 256, 3) for i in range(track_num) for j in range(16)}
 for note in notes:
 tr, c, p, t, d = note
 img[p, t: t + d] = colors[(tr, c)]
 img = PIL.Image.fromarray(np.flip(img, 0))
 return img

 def augment(self, midi_seq, max_pitch_shift=4, max_vel_shift=10, max_cc_val_shift=10, max_bpm_shift=10,
 max_track_shift=0, max_channel_shift=16):
 pitch_shift = random.randint(-max_pitch_shift, max_pitch_shift)
 vel_shift = random.randint(-max_vel_shift, max_vel_shift)
 cc_val_shift = random.randint(-max_cc_val_shift, max_cc_val_shift)
 bpm_shift = random.randint(-max_bpm_shift, max_bpm_shift)
 track_shift = random.randint(0, max_track_shift)
 channel_shift = random.randint(0, max_channel_shift)
 midi_seq_new = []
 for tokens in midi_seq:
 tokens_new = [*tokens]
 if tokens[0] in self.id_events:
 name = self.id_events[tokens[0]]
 for i, pn in enumerate(self.events[name]):
 if pn == "track":
 tr = tokens[1 + i] - self.parameter_ids[pn][0]
 tr += track_shift
 tr = tr % self.event_parameters[pn]
 tokens_new[1 + i] = self.parameter_ids[pn][tr]
 elif pn == "channel":
 c = tokens[1 + i] - self.parameter_ids[pn][0]
 c0 = c
 c += channel_shift
 c = c % self.event_parameters[pn]
 if c0 == 9:
 c = 9
 elif c == 9:
 c = (9 + channel_shift) % self.event_parameters[pn]
 tokens_new[1 + i] = self.parameter_ids[pn][c]

 if name == "note":
 c = tokens[5] - self.parameter_ids["channel"][0]
 p = tokens[6] - self.parameter_ids["pitch"][0]
 v = tokens[7] - self.parameter_ids["velocity"][0]
 if c != 9: # no shift for drums
 p += pitch_shift
 if not 0 <= p < 128:
 return midi_seq
 v += vel_shift
 v = max(1, min(127, v))
 tokens_new[6] = self.parameter_ids["pitch"][p]
 tokens_new[7] = self.parameter_ids["velocity"][v]
 elif name == "control_change":
 cc = tokens[5] - self.parameter_ids["controller"][0]
 val = tokens[6] - self.parameter_ids["value"][0]
 if cc in [1, 2, 7, 11]:
 val += cc_val_shift
 val = max(1, min(127, val))
 tokens_new[6] = self.parameter_ids["value"][val]
 elif name == "set_tempo":
 bpm = tokens[4] - self.parameter_ids["bpm"][0]
 bpm += bpm_shift
 bpm = max(1, min(255, bpm))
 tokens_new[4] = self.parameter_ids["bpm"][bpm]
 midi_seq_new.append(tokens_new)
 return midi_seq_new

 def check_quality(self, midi_seq, alignment_min=0.3, tonality_min=0.8, piano_max=0.7, notes_bandwidth_min=3,
 notes_density_max=50, notes_density_min=2.5, total_notes_max=20000, total_notes_min=256,
 note_window_size=16):
 total_notes = 0
 channels = []
 time_hist = [0] * 16
 note_windows = {}
 notes_sametime = []
 notes_density_list = []
 tonality_list = []
 notes_bandwidth_list = []
 instruments = {}
 piano_channels = []
 abs_t1 = 0
 last_t = 0
 for tsi, tokens in enumerate(midi_seq):
 event = self.tokens2event(tokens)
 if not event:
 continue
 t1, t2, tr = event[1:4]
 abs_t1 += t1
 t = abs_t1 * 16 + t2
 c = None
 if event[0] == "note":
 d, c, p, v = event[4:]
 total_notes += 1
 time_hist[t2] += 1
 if c != 9: # ignore drum channel
 if c not in instruments:
 instruments[c] = 0
 if c not in piano_channels:
 piano_channels.append(c)
 note_windows.setdefault(abs_t1 // note_window_size, []).append(p)
 if last_t != t:
 notes_sametime = [(et, p_) for et, p_ in notes_sametime if et > last_t]
 notes_sametime_p = [p_ for _, p_ in notes_sametime]
 if len(notes_sametime) > 0:
 notes_bandwidth_list.append(max(notes_sametime_p) - min(notes_sametime_p))
 notes_sametime.append((t + d - 1, p))
 elif event[0] == "patch_change":
 c, p = event[4:]
 instruments[c] = p
 if p == 0 and c not in piano_channels:
 piano_channels.append(c)
 if c is not None and c not in channels:
 channels.append(c)
 last_t = t
 reasons = []
 if total_notes < total_notes_min:
 reasons.append("total_min")
 if total_notes > total_notes_max:
 reasons.append("total_max")
 if len(note_windows) == 0 and total_notes > 0:
 reasons.append("drum_only")
 if reasons:
 return False, reasons
 time_hist = sorted(time_hist, reverse=True)
 alignment = sum(time_hist[:2]) / total_notes
 for notes in note_windows.values():
 key_hist = [0] * 12
 for p in notes:
 key_hist[p % 12] += 1
 key_hist = sorted(key_hist, reverse=True)
 tonality_list.append(sum(key_hist[:7]) / len(notes))
 notes_density_list.append(len(notes) / note_window_size)
 tonality_list = sorted(tonality_list)
 tonality = sum(tonality_list) / len(tonality_list)
 notes_bandwidth = sum(notes_bandwidth_list) / len(notes_bandwidth_list) if notes_bandwidth_list else 0
 notes_density = max(notes_density_list) if notes_density_list else 0
 piano_ratio = len(piano_channels) / len(channels)
 if len(channels) <= 3: # ignore piano threshold if it is a piano solo midi
 piano_max = 1
 if alignment < alignment_min: # check weather the notes align to the bars (because some midi files are recorded)
 reasons.append("alignment")
 if tonality < tonality_min: # check whether the music is tonal
 reasons.append("tonality")
 if notes_bandwidth < notes_bandwidth_min: # check whether music is melodic line only
 reasons.append("bandwidth")
 if not notes_density_min < notes_density < notes_density_max:
 reasons.append("density")
 if piano_ratio > piano_max: # check whether most instruments is piano (because some midi files don't have instruments assigned correctly)
 reasons.append("piano")
 return not reasons, reasons


class MIDITokenizerV2:
 def __init__(self):
 self.version = "v2"
 self.optimise_midi = False
 self.vocab_size = 0

 def allocate_ids(size):
 ids = [self.vocab_size + i for i in range(size)]
 self.vocab_size += size
 return ids

 self.pad_id = allocate_ids(1)[0]
 self.bos_id = allocate_ids(1)[0]
 self.eos_id = allocate_ids(1)[0]
 self.events = {
 "note": ["time1", "time2", "track", "channel", "pitch", "velocity", "duration"],
 "patch_change": ["time1", "time2", "track", "channel", "patch"],
 "control_change": ["time1", "time2", "track", "channel", "controller", "value"],
 "set_tempo": ["time1", "time2", "track", "bpm"],
 "time_signature": ["time1", "time2", "track", "nn", "dd"],
 "key_signature": ["time1", "time2", "track", "sf", "mi"],
 }
 self.event_parameters = {
 "time1": 128, "time2": 16, "duration": 2048, "track": 128, "channel": 16, "pitch": 128, "velocity": 128,
 "patch": 128, "controller": 128, "value": 128, "bpm": 384, "nn": 16, "dd": 4, "sf": 15, "mi": 2
 }
 self.event_ids = {e: allocate_ids(1)[0] for e in self.events.keys()}
 self.id_events = {i: e for e, i in self.event_ids.items()}
 self.parameter_ids = {p: allocate_ids(s) for p, s in self.event_parameters.items()}
 self.max_token_seq = max([len(ps) for ps in self.events.values()]) + 1

 def to_dict(self) -> Dict[str, Any]:
 d = {
 "version":self.version,
 "optimise_midi":self.optimise_midi,
 "vocab_size": self.vocab_size,
 "events": self.events,
 "event_parameters": self.event_parameters,
 "max_token_seq": self.max_token_seq,
 "pad_id": self.pad_id,
 "bos_id": self.bos_id,
 "eos_id": self.eos_id,
 }
 return d

 def set_optimise_midi(self, optimise_midi=True):
 self.optimise_midi = optimise_midi

 @staticmethod
 def tempo2bpm(tempo):
 tempo = tempo / 10 ** 6 # us to s
 bpm = 60 / tempo
 return bpm

 @staticmethod
 def bpm2tempo(bpm):
 if bpm == 0:
 bpm = 1
 tempo = int((60 / bpm) * 10 ** 6)
 return tempo

 @staticmethod
 def sf2key(sf):
 # sf in key_signature to key.
 # key represents the sequence from C note to B note (12 in total)
 return (sf * 7) % 12

 @staticmethod
 def key2sf(k, mi):
 # key to sf
 sf = (k * 7) % 12
 if sf > 6 or (mi == 1 and sf >= 5):
 sf -= 12
 return sf

 @staticmethod
 def detect_key_signature(key_hist, threshold=0.7):
 if len(key_hist) != 12:
 return None
 if sum(key_hist) == 0:
 return None
 p = sum(sorted(key_hist, reverse=True)[:7]) / sum(key_hist)
 if p < threshold:
 return None
 keys = [x[1] for x in sorted(zip(key_hist, range(len(key_hist))), reverse=True, key=lambda x: x[0])[:7]]
 keys = sorted(keys)
 semitones = []
 for i in range(len(keys)):
 dis = keys[i] - keys[i - 1]
 if dis == 1 or dis == -11:
 semitones.append(keys[i])
 if len(semitones) != 2:
 return None
 semitones_dis = semitones[1] - semitones[0]
 if semitones_dis == 5:
 root_key = semitones[0]
 elif semitones_dis == 7:
 root_key = semitones[1]
 else:
 return None
 return root_key

 def tokenize(self, midi_score, add_bos_eos=True, cc_eps=4, tempo_eps=4,
 remap_track_channel=None, add_default_instr=None, remove_empty_channels=None):
 if remap_track_channel is None: # set default value
 remap_track_channel = self.optimise_midi
 if add_default_instr is None:
 add_default_instr = self.optimise_midi
 if remove_empty_channels is None:
 remove_empty_channels = self.optimise_midi

 ticks_per_beat = midi_score[0]
 event_list = {}
 track_idx_map = {i: dict() for i in range(16)}
 track_idx_dict = {}
 channels = []
 patch_channels = []
 empty_channels = [True] * 16
 channel_note_tracks = {i: list() for i in range(16)}
 note_key_hist = [0]*12
 key_sigs = []
 track_to_channels = {}
 for track_idx, track in enumerate(midi_score[1:129]):
 last_notes = {}
 patch_dict = {}
 control_dict = {}
 last_bpm = 0
 track_channels = []
 track_to_channels.setdefault(track_idx, track_channels)
 for event in track:
 if event[0] not in self.events:
 continue
 name = event[0]
 c = -1
 t = round(16 * event[1] / ticks_per_beat) # quantization
 new_event = [name, t // 16, t % 16, track_idx]
 if name == "note":
 d, c, p, v = event[2:]
 if not (0 <= c <= 15):
 continue
 d = max(1, round(16 * d / ticks_per_beat))
 new_event += [c, p, v, d]
 empty_channels[c] = False
 track_idx_dict.setdefault(c, track_idx)
 note_tracks = channel_note_tracks[c]
 if track_idx not in note_tracks:
 note_tracks.append(track_idx)
 if c != 9:
 note_key_hist[p%12] += 1
 if c not in track_channels:
 track_channels.append(c)
 elif name == "patch_change":
 c, p = event[2:]
 if not (0 <= c <= 15):
 continue
 new_event += [c, p]
 last_p = patch_dict.setdefault(c, None)
 if last_p == p:
 continue
 patch_dict[c] = p
 if c not in patch_channels:
 patch_channels.append(c)
 elif name == "control_change":
 c, cc, v = event[2:]
 if not (0 <= c <= 15):
 continue
 new_event += [c, cc, v]
 last_v = control_dict.setdefault((c, cc), 0)
 if abs(last_v - v) < cc_eps:
 continue
 control_dict[(c, cc)] = v
 elif name == "set_tempo":
 tempo = event[2]
 if tempo == 0: # invalid tempo
 continue
 bpm = min(int(self.tempo2bpm(tempo)), 383)
 new_event += [bpm]
 if abs(last_bpm - bpm) < tempo_eps:
 continue
 last_bpm = bpm
 elif name == "time_signature":
 nn, dd = event[2:4]
 if not (1 <= nn <= 16 and 1 <= dd <= 4): # invalid
 continue
 nn -= 1 # make it start from 0
 dd -= 1
 new_event += [nn, dd]
 elif name == "key_signature":
 sf, mi = event[2:]
 if not (-7 <= sf <= 7 and 0 <= mi <= 1): # invalid
 continue
 sf += 7
 new_event += [sf, mi]
 key_sigs.append(new_event)

 if name in ["note", "time_signature", "key_signature"]:
 key = tuple(new_event[:-2])
 else:
 key = tuple(new_event[:-1])

 if c != -1:
 if c not in channels:
 channels.append(c)
 tr_map = track_idx_map[c]
 if track_idx not in tr_map:
 tr_map[track_idx] = 0

 if event[0] == "note": # to eliminate note overlap due to quantization
 cp = tuple(new_event[4:6]) # channel pitch
 if cp in last_notes:
 last_note_key, last_note = last_notes[cp]
 last_t = last_note[1] * 16 + last_note[2]
 last_note[-1] = max(0, min(last_note[-1], t - last_t)) # modify duration
 if last_note[-1] == 0:
 event_list.pop(last_note_key)
 last_notes[cp] = (key, new_event)
 event_list[key] = new_event
 event_list = list(event_list.values())

 empty_channels = [c for c in channels if empty_channels[c]]

 if remap_track_channel:
 patch_channels = []
 channels_count = 0
 channels_map = {9: 9} if 9 in channels else {}
 if remove_empty_channels:
 channels = sorted(channels, key=lambda x: 1 if x in empty_channels else 0)
 for c in channels:
 if c == 9:
 continue
 channels_map[c] = channels_count
 channels_count += 1
 if channels_count == 9:
 channels_count = 10
 channels = list(channels_map.values())

 track_count = 0
 track_idx_map_order = [k for k, v in sorted(list(channels_map.items()), key=lambda x: x[1])]
 for c in track_idx_map_order: # tracks not to remove
 if remove_empty_channels and c in empty_channels:
 continue
 tr_map = track_idx_map[c]
 for track_idx in tr_map:
 note_tracks = channel_note_tracks[c]
 if len(note_tracks) != 0 and track_idx not in note_tracks:
 continue
 track_count += 1
 tr_map[track_idx] = track_count
 for c in track_idx_map_order: # tracks to remove
 if not (remove_empty_channels and c in empty_channels):
 continue
 tr_map = track_idx_map[c]
 for track_idx in tr_map:
 note_tracks = channel_note_tracks[c]
 if not (len(note_tracks) != 0 and track_idx not in note_tracks):
 continue
 track_count += 1
 tr_map[track_idx] = track_count

 empty_channels = [channels_map[c] for c in empty_channels]
 track_idx_dict = {}
 key_sigs = []
 key_signature_to_add = []
 key_signature_to_remove = []
 for event in event_list:
 name = event[0]
 track_idx = event[3]
 if name == "note":
 c = event[4]
 event[4] = channels_map[c] # channel
 event[3] = track_idx_map[c][track_idx] # track
 track_idx_dict.setdefault(event[4], event[3])
 # setdefault, so the track_idx is first of the channel
 elif name in ["set_tempo", "time_signature"]:
 event[3] = 0 # set track 0 for meta events
 elif name == "key_signature":
 new_channel_track_idxs = []
 for c, tr_map in track_idx_map.items():
 if track_idx in tr_map:
 new_track_idx = tr_map[track_idx]
 c = channels_map[c]
 new_channel_track_idx = (c, new_track_idx)
 if new_track_idx == 0:
 continue
 if new_channel_track_idx not in new_channel_track_idxs:
 new_channel_track_idxs.append(new_channel_track_idx)

 if len(new_channel_track_idxs) == 0:
 if event[3] == 0: # keep key_signature on track 0 (meta)
 key_sigs.append(event)
 continue
 event[3] = -1 # avoid remove same event
 key_signature_to_remove.append(event) # empty track
 continue
 c, nt = new_channel_track_idxs[0]
 event[3] = nt
 key_sigs.append(event)
 if c == 9:
 event[4] = 7 # sf=0
 for c, nt in new_channel_track_idxs[1:]:
 new_event = [*event]
 new_event[3] = nt
 if c == 9:
 new_event[4] = 7 # sf=0
 key_sigs.append(new_event)
 key_signature_to_add.append(new_event)
 elif name == "control_change" or name == "patch_change":
 c = event[4]
 event[4] = channels_map[c] # channel
 tr_map = track_idx_map[c]
 # move the event to first track of the channel if it's original track is empty
 note_tracks = channel_note_tracks[c]
 if len(note_tracks) != 0 and track_idx not in note_tracks:
 track_idx = channel_note_tracks[c][0]
 new_track_idx = tr_map[track_idx]
 event[3] = new_track_idx
 if name == "patch_change" and event[4] not in patch_channels:
 patch_channels.append(event[4])
 for key_sig in key_signature_to_remove:
 event_list.remove(key_sig)
 event_list += key_signature_to_add
 track_to_channels ={}
 for c, tr_map in track_idx_map.items():
 if c not in channels_map:
 continue
 c = channels_map[c]
 for _, track_idx in tr_map.items():
 track_to_channels.setdefault(track_idx, [])
 cs = track_to_channels[track_idx]
 if c not in cs:
 cs.append(c)

 if add_default_instr:
 for c in channels:
 if c not in patch_channels and c in track_idx_dict:
 event_list.append(["patch_change", 0, 0, track_idx_dict[c], c, 0])

 if len(key_sigs) == 0 or all([key_sig[4]==7 for key_sig in key_sigs]):
 # detect key signature or fix the default key signature
 root_key = self.detect_key_signature(note_key_hist)
 if root_key is not None:
 sf = self.key2sf(root_key, 0)
 # print("detect_key_signature",sf)
 if len(key_sigs) == 0:
 for tr, cs in track_to_channels.items():
 if remap_track_channel and tr == 0:
 continue
 new_event = ["key_signature", 0, 0, tr, (0 if (len(cs) == 1 and cs[0] == 9) else sf) + 7, 0]
 event_list.append(new_event)
 else:
 for key_sig in key_sigs:
 tr = key_sig[3]
 if tr in track_to_channels:
 cs = track_to_channels[tr]
 if len(cs) == 1 and cs[0] == 9:
 continue
 key_sig[4] = sf + 7
 key_sig[5] = 0
 else:
 # remove default key signature
 for key_sig in key_sigs:
 event_list.remove(key_sig)

 events_name_order = ["time_signature", "key_signature", "set_tempo", "patch_change", "control_change", "note"]
 events_name_order = {name: i for i, name in enumerate(events_name_order)}
 events_order = lambda e: e[1:4] + [events_name_order[e[0]]]
 event_list = sorted(event_list, key=events_order)

 setup_events = {}
 notes_in_setup = False
 for i, event in enumerate(event_list): # optimise setup
 new_event = [*event] # make copy of event
 if event[0] not in ["note", "time_signature"]:
 new_event[1] = 0
 new_event[2] = 0
 has_next = False
 has_pre = False
 if i < len(event_list) - 1:
 next_event = event_list[i + 1]
 has_next = event[1] + event[2] == next_event[1] + next_event[2]
 if notes_in_setup and i > 0:
 pre_event = event_list[i - 1]
 has_pre = event[1] + event[2] == pre_event[1] + pre_event[2]
 if (event[0] == "note" and not has_next) or (notes_in_setup and not has_pre):
 event_list = sorted(setup_events.values(), key=events_order) + event_list[i:]
 break
 else:
 if event[0] == "note":
 notes_in_setup = True
 if event[0] in ["note", "time_signature", "key_signature"]:
 key = tuple([event[0]]+event[3:-2])
 else:
 key = tuple([event[0]]+event[3:-1])
 setup_events[key] = new_event

 last_t1 = 0
 midi_seq = []
 for event in event_list:
 if remove_empty_channels and event[0] in ["control_change", "patch_change"] and event[4] in empty_channels:
 continue
 cur_t1 = event[1]
 event[1] = event[1] - last_t1
 tokens = self.event2tokens(event)
 if not tokens:
 continue
 midi_seq.append(tokens)
 last_t1 = cur_t1

 if add_bos_eos:
 bos = [self.bos_id] + [self.pad_id] * (self.max_token_seq - 1)
 eos = [self.eos_id] + [self.pad_id] * (self.max_token_seq - 1)
 midi_seq = [bos] + midi_seq + [eos]
 return midi_seq

 def event2tokens(self, event):
 name = event[0]
 params = event[1:]
 if not all([0 <= params[i] < self.event_parameters[p] for i, p in enumerate(self.events[name])]):
 return []
 tokens = [self.event_ids[name]] + [self.parameter_ids[p][params[i]]
 for i, p in enumerate(self.events[name])]
 tokens += [self.pad_id] * (self.max_token_seq - len(tokens))
 return tokens

 def tokens2event(self, tokens):
 if tokens[0] not in self.id_events:
 return []
 name = self.id_events[tokens[0]]
 if len(tokens) <= len(self.events[name]):
 return []
 params = tokens[1:]
 params = [params[i] - self.parameter_ids[p][0] for i, p in enumerate(self.events[name])]
 if not all([0 <= params[i] < self.event_parameters[p] for i, p in enumerate(self.events[name])]):
 return []
 event = [name] + params
 return event

 def detokenize(self, midi_seq):
 ticks_per_beat = 480
 tracks_dict = {}
 t1 = 0
 for tokens in midi_seq:
 if tokens[0] in self.id_events:
 event = self.tokens2event(tokens)
 if not event:
 continue
 name = event[0]
 t1 += event[1]
 t = t1 * 16 + event[2]
 t = int(t * ticks_per_beat / 16)
 track_idx = event[3]
 event_new = [name, t]
 if name == "note":
 c, p, v, d = event[4:]
 d = int(d * ticks_per_beat / 16)
 event_new += [d, c, p, v]
 elif name == "control_change" or name == "patch_change":
 event_new += event[4:]
 elif name == "set_tempo":
 event_new += [self.bpm2tempo(event[4])]
 elif name == "time_signature":
 nn, dd = event[4:]
 nn += 1
 dd += 1
 event_new += [nn, dd, 24, 8] # usually cc, bb = 24, 8
 elif name == "key_signature":
 sf, mi = event[4:]
 sf -= 7
 event_new += [sf, mi]
 else: # should not go here
 continue
 if track_idx not in tracks_dict:
 tracks_dict[track_idx] = []
 tracks_dict[track_idx].append(event_new)
 tracks = [tr for idx, tr in sorted(list(tracks_dict.items()), key=lambda it: it[0])]

 for i in range(len(tracks)): # to eliminate note overlap
 track = tracks[i]
 track = sorted(track, key=lambda e: e[1])
 last_note_t = {}
 zero_len_notes = []
 for e in reversed(track):
 if e[0] == "note":
 t, d, c, p = e[1:5]
 key = (c, p)
 if key in last_note_t:
 d = min(d, max(last_note_t[key] - t, 0))
 last_note_t[key] = t
 e[2] = d
 if d == 0:
 zero_len_notes.append(e)
 for e in zero_len_notes:
 track.remove(e)
 tracks[i] = track
 return [ticks_per_beat, *tracks]

 def midi2img(self, midi_score):
 ticks_per_beat = midi_score[0]
 notes = []
 max_time = 1
 track_num = len(midi_score[1:])
 for track_idx, track in enumerate(midi_score[1:]):
 for event in track:
 t = round(16 * event[1] / ticks_per_beat)
 if event[0] == "note":
 d = max(1, round(16 * event[2] / ticks_per_beat))
 c, p = event[3:5]
 max_time = max(max_time, t + d + 1)
 notes.append((track_idx, c, p, t, d))
 img = np.zeros((128, max_time, 3), dtype=np.uint8)
 colors = {(i, j): np.random.randint(50, 256, 3) for i in range(track_num) for j in range(16)}
 for note in notes:
 tr, c, p, t, d = note
 img[p, t: t + d] = colors[(tr, c)]
 img = PIL.Image.fromarray(np.flip(img, 0))
 return img

 def augment(self, midi_seq, max_pitch_shift=4, max_vel_shift=10, max_cc_val_shift=10, max_bpm_shift=10,
 max_track_shift=0, max_channel_shift=16):
 pitch_shift = random.randint(-max_pitch_shift, max_pitch_shift)
 vel_shift = random.randint(-max_vel_shift, max_vel_shift)
 cc_val_shift = random.randint(-max_cc_val_shift, max_cc_val_shift)
 bpm_shift = random.randint(-max_bpm_shift, max_bpm_shift)
 track_shift = random.randint(0, max_track_shift)
 channel_shift = random.randint(0, max_channel_shift)
 midi_seq_new = []
 key_signature_tokens = []
 track_to_channels = {}
 for tokens in midi_seq:
 tokens_new = [*tokens]
 if tokens[0] in self.id_events:
 name = self.id_events[tokens[0]]
 for i, pn in enumerate(self.events[name]):
 if pn == "track":
 tr = tokens[1 + i] - self.parameter_ids[pn][0]
 tr += track_shift
 tr = tr % self.event_parameters[pn]
 tokens_new[1 + i] = self.parameter_ids[pn][tr]
 elif pn == "channel":
 c = tokens[1 + i] - self.parameter_ids[pn][0]
 c0 = c
 c += channel_shift
 c = c % self.event_parameters[pn]
 if c0 == 9:
 c = 9
 elif c == 9:
 c = (9 + channel_shift) % self.event_parameters[pn]
 tokens_new[1 + i] = self.parameter_ids[pn][c]

 if name == "note":
 tr = tokens[3] - self.parameter_ids["track"][0]
 c = tokens[4] - self.parameter_ids["channel"][0]
 p = tokens[5] - self.parameter_ids["pitch"][0]
 v = tokens[6] - self.parameter_ids["velocity"][0]
 if c != 9: # no shift for drums
 p += pitch_shift
 if not 0 <= p < 128:
 return midi_seq
 v += vel_shift
 v = max(1, min(127, v))
 tokens_new[5] = self.parameter_ids["pitch"][p]
 tokens_new[6] = self.parameter_ids["velocity"][v]
 track_to_channels.setdefault(tr, [])
 cs = track_to_channels[tr]
 if c not in cs:
 cs.append(c)
 elif name == "control_change":
 cc = tokens[5] - self.parameter_ids["controller"][0]
 val = tokens[6] - self.parameter_ids["value"][0]
 if cc in [1, 2, 7, 11]:
 val += cc_val_shift
 val = max(1, min(127, val))
 tokens_new[6] = self.parameter_ids["value"][val]
 elif name == "set_tempo":
 bpm = tokens[4] - self.parameter_ids["bpm"][0]
 bpm += bpm_shift
 bpm = max(1, min(383, bpm))
 tokens_new[4] = self.parameter_ids["bpm"][bpm]
 elif name == "key_signature":
 sf = tokens[4] - self.parameter_ids["sf"][0]
 mi = tokens[5] - self.parameter_ids["mi"][0]
 sf -= 7
 k = self.sf2key(sf)
 k = (k + pitch_shift) % 12
 sf = self.key2sf(k, mi)
 sf += 7
 tokens_new[4] = self.parameter_ids["sf"][sf]
 tokens_new[5] = self.parameter_ids["mi"][mi]
 key_signature_tokens.append(tokens_new)
 midi_seq_new.append(tokens_new)
 for tokens in key_signature_tokens:
 tr = tokens[3] - self.parameter_ids["track"][0]
 if tr in track_to_channels:
 cs = track_to_channels[tr]
 if len(cs) == 1 and cs[0] == 9:
 tokens[4] = self.parameter_ids["sf"][7] # sf=0
 return midi_seq_new

 def check_quality(self, midi_seq, alignment_min=0.3, tonality_min=0.8, piano_max=0.7, notes_bandwidth_min=3,
 notes_density_max=50, notes_density_min=2.5, total_notes_max=20000, total_notes_min=256,
 note_window_size=16):
 total_notes = 0
 channels = []
 time_hist = [0] * 16
 note_windows = {}
 notes_sametime = []
 notes_density_list = []
 tonality_list = []
 notes_bandwidth_list = []
 instruments = {}
 piano_channels = []
 abs_t1 = 0
 last_t = 0
 for tsi, tokens in enumerate(midi_seq):
 event = self.tokens2event(tokens)
 if not event:
 continue
 t1, t2, tr = event[1:4]
 abs_t1 += t1
 t = abs_t1 * 16 + t2
 c = None
 if event[0] == "note":
 c, p, v, d = event[4:]
 total_notes += 1
 time_hist[t2] += 1
 if c != 9: # ignore drum channel
 if c not in instruments:
 instruments[c] = 0
 if c not in piano_channels:
 piano_channels.append(c)
 note_windows.setdefault(abs_t1 // note_window_size, []).append(p)
 if last_t != t:
 notes_sametime = [(et, p_) for et, p_ in notes_sametime if et > last_t]
 notes_sametime_p = [p_ for _, p_ in notes_sametime]
 if len(notes_sametime) > 0:
 notes_bandwidth_list.append(max(notes_sametime_p) - min(notes_sametime_p))
 notes_sametime.append((t + d - 1, p))
 elif event[0] == "patch_change":
 c, p = event[4:]
 instruments[c] = p
 if p == 0 and c not in piano_channels:
 piano_channels.append(c)
 if c is not None and c not in channels:
 channels.append(c)
 last_t = t
 reasons = []
 if total_notes < total_notes_min:
 reasons.append("total_min")
 if total_notes > total_notes_max:
 reasons.append("total_max")
 if len(note_windows) == 0 and total_notes > 0:
 reasons.append("drum_only")
 if reasons:
 return False, reasons
 time_hist = sorted(time_hist, reverse=True)
 alignment = sum(time_hist[:2]) / total_notes
 for notes in note_windows.values():
 key_hist = [0] * 12
 for p in notes:
 key_hist[p % 12] += 1
 key_hist = sorted(key_hist, reverse=True)
 tonality_list.append(sum(key_hist[:7]) / len(notes))
 notes_density_list.append(len(notes) / note_window_size)
 tonality_list = sorted(tonality_list)
 tonality = sum(tonality_list) / len(tonality_list)
 notes_bandwidth = sum(notes_bandwidth_list) / len(notes_bandwidth_list) if notes_bandwidth_list else 0
 notes_density = max(notes_density_list) if notes_density_list else 0
 piano_ratio = len(piano_channels) / len(channels)
 if len(channels) <= 3: # ignore piano threshold if it is a piano solo midi
 piano_max = 1
 if alignment < alignment_min: # check weather the notes align to the bars (because some midi files are recorded)
 reasons.append("alignment")
 if tonality < tonality_min: # check whether the music is tonal
 reasons.append("tonality")
 if notes_bandwidth < notes_bandwidth_min: # check whether music is melodic line only
 reasons.append("bandwidth")
 if not notes_density_min < notes_density < notes_density_max:
 reasons.append("density")
 if piano_ratio > piano_max: # check whether most instruments is piano (because some midi files don't have instruments assigned correctly)
 reasons.append("piano")
 return not reasons, reasons


class MIDITokenizer:
 def __new__(cls, version="v2"):
 if version == "v1":
 return MIDITokenizerV1()
 elif version == "v2":
 return MIDITokenizerV2()
 else:
 raise ValueError(f"Unsupported version: {version}")