RAD Audio Disk

A RAD audio disc is a plain filesystem tree (a folder, a .iso, or a burned optical disc) with no manifest beyond one flat YAML file. Everything a player needs is either in filelist.txt, in metadata.yaml, or already embedded in each track's own audio tags.

Files

Exactly these names, all at the disc root (no subdirectories):

	filelist.txt (required)	Every other file's name, one per line, in burn order. Does not list itself.
	metadata.yaml (required)	Flat key/value scalars, plus one `tracks` list. See below.
	cover.jpg / cover.png	Front cover.
	back.jpg / back.png	Back cover.
	booklet1.jpg, booklet2.jpg, ...	Extra art pages, in order. Any count.
	art1.jpg, art2.jpg, ...	Any other image (disc art, tray, a photo) that isn't cover/back/a booklet page.
	album.md	Album blurb / liner notes, plain Markdown.
	artist.md	Artist bio, plain Markdown.
	track01.lrc, track02.lrc, ...	Lyrics for the track with the same number. `.lrc` (timed) or `.txt` (plain).
	track01.flac, track02.flac, ... (required, at least one)	`.flac` or `.wav`. Two-digit-and-up, ascending.

Nothing else is defined. A player must not choke on stray files it doesn't recognize, and a maker must not invent new ones.

Burn order

filelist.txt is itself the first file. Everything else follows it in this order: metadata.yaml, album.md, artist.md, cover.*, back.*, booklet*.*, art*.*, then all lyrics files (track01.lrc ... in ascending order), then all audio files (track01.flac ... in ascending order).

Lyrics come before audio, and every small file comes before every large one.

`metadata.yaml`

Flat key/value scalars, plus one tracks list. Unrecognized fields are ignored, not rejected.

album: Eine kleine Nachtmusik
artist: Wolfgang Amadeus Mozart
year: 1787
remastered: 2015        # only when this edition's date differs from `year`
label: Chamber Classics
genre: Classical
tracks:
  - Allegro
  - Romance
  - Rondo

album, artist: the disc's own title and artist.
year: original release year. remastered: this edition's year, only present when it differs from year.
tracks: titles in track order. Not the source of truth for anything else about a track.

Everything else about a track (artist, composer, ISRC, track number) comes from the audio file's own tags, not from here.