Why do tag power users convert AAC to FLAC before bulk edits?
m4a AAC stores atoms that map inconsistently across iTunes, Music, Mp3tag, and MusicBee—sort keys, composers, and multi-artist strings love to drift. Searchers type mp3tag flac, foobar mass tag, aac metadata mess, DISCNUMBER flac, and batch rename podcast because FLAC Vorbis comments are flatter and friendlier to scripted cleanup. Define UTF-8, BOM, slash-separated artists, and custom keys in a team README before interns regex the entire library. Embedding multi-megabyte scans inside every FLAC slows tag reads—resize art or host hi-res scans elsewhere. Copying ISRC or rights comments does not expand distribution licenses when the container changes. Ai2Done keeps the tags variant meticulous: export a key map, pilot ten tracks with diff tools, batch, then grep the library for missing DATE fields or oversize art before locking read-only releases.
How to migrate AAC metadata into FLAC without breaking sort orders
- Open AAC to FLAC, choose the tag-friendly variant, publish a field dictionary for artist, album artist, title, date, track, disc, and comment keys your stack expects.
- Convert ten pilot tracks, run Mp3tag or MusicBee regex passes on feat. strings and classical work titles, and compare playlist order against the old AAC view.
- Batch, run automated greps for empty DATE or DISCNUMBER, route anomalies to humans, and freeze write access on the FLAC tree until QA signs the spreadsheet.