M4A and Sonos (Sonos doesn't seem to recognize Album & Title)

Hello everyone,

I hope this is not a dumb question, but I seem to have a problem with Sonos not being able to read certain M4A metadata, namely Album and Title.
I use a little external hardrive connected to a Fritzbox as a poor man's NAS. The NAS stores a copy of my digital files and is hooked up to my Sonos system. The formats I use are lossless FLAC, MP3, M4A from iTunes (all of them bought in the store) and self generated M4A (basically I am ripping audio from a streaming service as a speed up workaround to digitize my records).
I would say 99,9% of my files have good tag quality.

Sonos reads tags just fine from everything EXCEPT the self-generated M4A files. There I only can find an album by browsing through the folder structure. And if I have several albums from an artist, they are shown on a flat level. It's a mess.

The strange thing - when I change tags from my itunes m4a collection via mp3tag, the changes are reflected just fine in Sonos.

Probably this problem is a Sonos issue (foobar, vlc etc.. read the data just fine too), but before I contact their support I wanted to check if anybody in this forum had this experience before.
Or is there a possibility to completely regenerate the m4a wrapper? If possible I would like to avoid a further transcoding.

Thanks for your thoughts and advice!

Aah, it looks like I can solve the problem by re-wrapping said files in ffmpeg. Just need to find the right batch process :slight_smile:

You can also try Utils > Optimize MP4 from the right-click context menu. Not sure if it solves the problem, though.

I found this thread:

Thank you Florian. I tried that but wasn't successful. FFMPEG it is.

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Maybe you should elaborate on this part to help people identify the cause.