"""Encode tagged MP3s, assemble the complete album, and build the local player.""" from pathlib import Path from concurrent.futures import ThreadPoolExecutor from html import escape import hashlib, json, subprocess, sys from build import run ROOT=Path(__file__).resolve().parent.parent NAME='after-the-last-bus' TITLE='After the Last Bus' def fmt(s): s=round(s);return f'{s//60}:{s%60:02d}' def sha(path): h=hashlib.sha256() with path.open('rb') as f: for b in iter(lambda:f.read(1024*1024),b''):h.update(b) return h.hexdigest() def encode(s): stem=s['stem'];dest=ROOT/'mp3'/f'{stem}.mp3' run(['ffmpeg','-hide_banner','-loglevel','error','-y','-i',ROOT/'wav'/f'{stem}.wav','-i',ROOT/'art'/'cover.png', '-map','0:a:0','-map','1:v:0','-c:a','libmp3lame','-b:a','320k','-c:v','png','-disposition:v','attached_pic','-id3v2_version','3', '-metadata',f'title={s["title"]}','-metadata','artist=Cairn','-metadata',f'album={TITLE}','-metadata',f'track={s["number"]}/8', '-metadata','date=2026','-metadata','genre=UK Garage / Dubstep','-metadata',f'TBPM={s["bpm"]}', '-metadata','comment=Original compositions and code-built instruments. Local edition.',dest]) print('Encoded:',s['title'],flush=True) def player(tracks,total): cards=[] for t in tracks: cards.append(f'') data=json.dumps([dict(title=t['title'],file=t['mp3']) for t in tracks]).replace(' After the Last Bus - Cairn
An empty bus shelter behind rain-streaked glass, with amber light on wet asphalt

Broken rhythms, wordless calls, and the long walk home. Eight original pieces for the hours between the last bus and the first light.

CAIRN / LOCAL EDITION

After the
Last Bus

8 tracks · '''+fmt(total)+''' · 120-140 BPM
UK garage · atmospheric dubstep · dub techno.

Choose a track.
'''+''.join(cards)+'''
''' # Keep the player fully portable in the listening ZIP, without duplicating # the entire album as both individual files and a second, combined MP3. html=html.replace(f'href="{NAME}-full-album.mp3" download>Download complete album',f'id="download" href="{tracks[0]["mp3"]}" download>Download selected track') html=html.replace('audio.src=tracks[n].file;',"audio.src=tracks[n].file;document.getElementById('download').href=tracks[n].file;") return html def main(): scores=json.loads((ROOT/'scores'/'manifest.json').read_text());tracks=[] for s in scores: check=json.loads((ROOT/'checks'/f'{s["stem"]}.json').read_text()) fingerprint=hashlib.sha256((ROOT/'scores'/f'{s["stem"]}.tsv').read_bytes()+(ROOT/'source'/'engine.cpp').read_bytes()).hexdigest() assert check['renderFingerprint']==fingerprint,'Master is stale: '+s['title'] tracks.append(dict(number=s['number'],title=s['title'],stem=s['stem'],seconds=check['seconds'],bpm=s['bpm'],key=s['key'],sections=s['sections'],description=s['description'],instrument=s['instrument'],mp3=f'mp3/{s["stem"]}.mp3',wav=f'wav/{s["stem"]}.wav',midi=f'midi/{s["stem"]}.mid')) with ThreadPoolExecutor(max_workers=2) as pool:list(pool.map(encode,scores)) total=sum(t['seconds'] for t in tracks) concat=ROOT/'work'/'concat-wav.txt';concat.write_text(''.join(f"file '../wav/{t['stem']}.wav'\n" for t in tracks)) chapters=[';FFMETADATA1'];cursor=0 for t in tracks: chapters+=['[CHAPTER]','TIMEBASE=1/1000',f'START={round(cursor*1000)}',f'END={round((cursor+t["seconds"])*1000)}','title='+t['title']];cursor+=t['seconds'] cp=ROOT/'work'/'chapters.ffmeta';cp.write_text('\n'.join(chapters)+'\n') full=ROOT/f'{NAME}-full-album.mp3' print('Assembling the complete album...',flush=True) run(['ffmpeg','-hide_banner','-loglevel','error','-y','-f','concat','-safe','0','-i',concat,'-i',ROOT/'art'/'cover.png','-i',cp, '-map','0:a:0','-map','1:v:0','-map_chapters','2','-c:a','libmp3lame','-b:a','320k','-c:v','png','-disposition:v','attached_pic','-id3v2_version','3', '-metadata',f'title={TITLE} - Complete Album','-metadata','artist=Cairn','-metadata',f'album={TITLE}','-metadata','date=2026','-metadata','genre=UK Garage / Dubstep',full]) for t in tracks:t['sha256']={fmt:sha(ROOT/t[fmt]) for fmt in ['mp3','wav','midi']} album=dict(title=TITLE,artist='Cairn',date='2026-09-13',genre='UK Garage / Dubstep / Dub Techno',brief='Original nocturnal UK garage, atmospheric dubstep and dub techno, with eight distinct custom lead engines',totalSeconds=total,displayDuration=fmt(total),tracks=tracks,completeAlbum=full.name,completeAlbumSha256=sha(full),masterFormat='44.1 kHz / 24-bit PCM stereo',mp3Format='320 kb/s stereo',localOnly=True) (ROOT/'album.json').write_text(json.dumps(album,indent=2)+'\n') (ROOT/'album.m3u8').write_text('#EXTM3U\n'+''.join(f'#EXTINF:{t["seconds"]:.3f},Cairn - {t["title"]}\n{t["mp3"]}\n' for t in tracks)) (ROOT/'tracklist.txt').write_text(TITLE+' - Cairn\n\n'+''.join(f'{t["number"]:02d} {fmt(t["seconds"])} {t["title"]} / {t["bpm"]} BPM / {t["key"]}\n' for t in tracks)+f'\nTotal: {fmt(total)}\n') (ROOT/'index.html').write_text(player(tracks,total)) (ROOT/'checks'/'sha256.txt').write_text(''.join(f'{t["sha256"][kind]} {t[kind]}\n' for t in tracks for kind in ['mp3','wav','midi'])+f'{album["completeAlbumSha256"]} {full.name}\n') print(json.dumps(dict(album=TITLE,total=fmt(total),tracks=len(tracks),completeAlbum=str(full))),flush=True) if __name__=='__main__': if '--player-only' in sys.argv: album=json.loads((ROOT/'album.json').read_text()) (ROOT/'index.html').write_text(player(album['tracks'],album['totalSeconds'])) else:main()