| |
| """ |
| midjson_to_mid.py |
| ================= |
| Consume the JSON event stream emitted by gp_to_keyswitched_mid.js and write |
| one Type-1 MIDI file per track into <out_dir>, named <TrackName>_keyswitched.mid. |
| |
| Usage: |
| node gp_to_keyswitched_mid.js input.gp out_dir > events.json |
| python midjson_to_mid.py events.json <out_dir> |
| """ |
| import json |
| import os |
| import re |
| import sys |
|
|
| import mido |
|
|
| _FORBIDDEN = re.compile(r'[\\/:\*\?"<>\|]+') |
| _WS = re.compile(r'\s+') |
|
|
|
|
| def sanitize(name, default="output"): |
| cleaned = _FORBIDDEN.sub(' ', name or '') |
| cleaned = _WS.sub(' ', cleaned).strip().rstrip('. ') |
| return cleaned or default |
|
|
|
|
| def write_track(mid, name, channel, events, ticks_per_beat=960): |
| track = mid.add_track(name[:127] if name else "Guitar") |
| last = 0 |
| for e in events: |
| tick = max(0, int(e['tick'])) |
| kind = e['kind'] |
| note = int(e['note']) |
| vel = int(e.get('velocity', 0)) |
| if kind == 'note_on' and vel > 0: |
| msg = mido.Message('note_on', channel=channel, note=note, |
| velocity=max(1, min(127, vel)), time=tick - last) |
| else: |
| msg = mido.Message('note_off', channel=channel, note=note, |
| velocity=0, time=tick - last) |
| track.append(msg) |
| last = tick |
| return track |
|
|
|
|
| def main(): |
| if len(sys.argv) < 3: |
| print("Usage: python midjson_to_mid.py <events.json> <out_dir>", |
| file=sys.stderr) |
| return 2 |
| events_path = sys.argv[1] |
| out_dir = sys.argv[2] |
| with open(events_path, 'r', encoding='utf-8') as f: |
| data = json.load(f) |
|
|
| os.makedirs(out_dir, exist_ok=True) |
| tempo = int(data.get('tempo', 120)) |
| ts = data.get('timeSignature', {}) |
| ts_num = int(ts.get('numerator', 4)) |
| ts_den = int(ts.get('denominator', 4)) |
|
|
| written = [] |
| for tr in data.get('tracks', []): |
| events = tr['events'] |
| if not events: |
| continue |
| mid = mido.MidiFile(type=1, ticks_per_beat=960) |
| conductor = mid.add_track("Conductor") |
| conductor.append(mido.MetaMessage( |
| 'set_tempo', tempo=mido.bpm2tempo(tempo), time=0)) |
| conductor.append(mido.MetaMessage( |
| 'time_signature', numerator=ts_num, denominator=ts_den, time=0)) |
| write_track(mid, tr['name'], int(tr['channel']), events) |
| fname = sanitize(tr['name']) + "_keyswitched.mid" |
| out_path = os.path.join(out_dir, fname) |
| mid.save(out_path) |
| |
| ks_notes = sum(1 for e in events if e['kind'] == 'note_on' and e.get('ks')) |
| played = sum(1 for e in events if e['kind'] == 'note_on' and not e.get('ks')) |
| written.append((out_path, tr['name'], tr['channel'], len(events), ks_notes, played)) |
|
|
| for out_path, name, ch, nev, ks, played in written: |
| size = os.path.getsize(out_path) |
| print(f" {os.path.basename(out_path)} ({size:,}B, ch={ch}) " |
| f"events={nev} keyswitch_on={ks} played_notes={played}") |
| print(f"\nWrote {len(written)} file(s) to {out_dir}") |
| return 0 |
|
|
|
|
| if __name__ == '__main__': |
| sys.exit(main()) |
