Edit the tags of your M4A files

M4A, AAC and ALAC

An .m4a file is an MP4 container that holds only sound: AAC, which is lossy, or ALAC, which is lossless. An .m4b file is the same thing, used for audiobooks. Their tags are stored in iTunes-specific fields, different from those of MP3 and FLAC files.

RustMusic reads both, and recognizes ALAC as lossless since version 0.4.2: files already imported are corrected during the update, and a rescan then refreshes their exact bit depth.

What you can edit

• Title, artist, album and album artist.
• Year, genre and comment.
• Composer: stored by iTunes in a separate field, it is shown and edited like the others.
• Track number and total tracks, disc number and total discs.
• Cover art: the front cover is placed first.

Editing the tags

1. 1

   Open the tag workshop

   Right-click an album, then “Edit tags”.

2. 2

   Fix or fill in

   In the table, or with “Complete online”, which looks up the values on MusicBrainz or Deezer.

3. 3

   Write the files

   “Write N files” (Ctrl+S) saves the changes to your .m4a files.

What is preserved

• The audio is never rewritten: only the tags change.
• The file’s other data is kept: lyrics, ReplayGain, MusicBrainz IDs and other iTunes information.
• Writing is safe, including on a NAS: the file is only replaced once it has been fully written.

What about other formats?

RustMusic writes tags to MP3, FLAC, DSF, DFF and MP4 (.m4a, .m4b) files. WAV, AIFF, Ogg and Opus files remain read-only.