What kind of metadata can be stored in m4a files?

I have a collection of voice recordings from my Android phone, all stored in .m4a files. I would like to know the date of the recording, but the file timestamps have all been set to the date at which I extracted the files from the phone.

When I play them in Totem, the metadata sidebar shows the correct year (e.g. 2013), which leads me to think there must be some metadata stored in the file. It's not just showing the current year, or the year of the file timestamp.

Neither mutagen-inspect nor puddletag reveal any tags.

What metadata can an m4a file hold and how do I get at it?

What metadata can an m4a file hold and how do I get at it?

Metadata for .m4a apple lossless (ALAC) files

My new music library is all nicely ripped Apple Lossless files in .m4a containers. These contain metadata, but it’s not id3v2 and the universe of mp3 tools mostly don’t work. ffmpeg’s ffprobe sort of works but doesn’t show all tags.

What does work for displaying m4a metadta is mp4v2, installable via Homebrew. Docs here. It seems pretty stable but still gets some updates.

(imac) = mp4file --list test.m4a
BRAND  COMPAT              SIZING  FILE
----------------------------------------------------------------------
M4A    M4A,isom,mp42       32-bit  test.m4a
 
(imac) = mp4info test.m4a
mp4info version 1.9.1
test.m4a:
Track   Type    Info
1   audio   alac, 260.806 secs, 562 kbps, 44100 Hz
 Name: Pastourelle (E passo de dossai: Ah! viens pres de moi), folksong for voice & orchestra (Chants d'Auvergne, Series 2, No. 1)
 Artist: Dawn Upshaw
 Composer: Joseph Canteloube
 Release Date: 1994
 Album: Canteloube: Songs of the Auvergne
 Track: 1 of 15
 Disk: 1 of 1
 Genre: Vocal Music
 BPM: 0
 Part of Compilation: no
 Cover Art pieces: 1
 Album Artist: Kent Nagano
 Media Type: Movie
 TV Episode: 0
 TV Season: 0

Source Metadata for .m4a apple lossless (ALAC) files

Mp3tag (http://www.mp3tag.de) is a universal tag editor which can tag mp3 and mp4 (including m4a) formats. Pls check.