Whether a file’s audio decodes cleanly, as beets’ badfiles plugin
asks with flac -t and mp3val: a truncated download or a corrupt
packet otherwise passes import, since tags and duration read fine, and is
found only when it plays. Decoded here with symphonia, so no external
tool is needed, and FLAC’s stored MD5 of the audio is checked as well.
Folds a featured artist out of the track artist and into the title, as
beets’ ftintitle plugin does: “Burial feat. Four Tet” under album
artist “Burial” becomes artist “Burial”, title “Song feat. Four Tet”.
Lyrics from LRCLIB, as beets’ lyrics plugin fetches them: synced (LRC)
where it has them, so players can scroll them, and plain otherwise.
LRCLIB needs no key and matches on artist, title, album and duration,
which is what keeps a live version or a remix from getting the album
cut’s words.
ReplayGain 2.0 track and album gain, as beets’ replaygain plugin
writes it: EBU R128 integrated loudness measured against the -18 LUFS
reference, and the sample peak. Players use it to play a quiet 1970s LP
and a limited 2020s master at the same loudness.