The problem seems to be with the version of ffmpeg that is installed in the latest release of the QNAP Operating System (QTS).
You might want to try this, it fixed the issue for me (command line knowledge required)…
- Enable the QNAP Club repository in the App Center (if not already done)
Instructions here… https://www.qnapclub.eu/en/howto/1
Go to the new repo in App Center and install ffmpeg - this will install version 4.3
Open a SSH (putty) session
Find where the current version of ffmpeg lives, mine (v3.3.6) was installed here…
- Rename it to ffmpeg_OLD
mv ffmpeg ffmpeg_OLD
- Go to the location of the new version
- copy it into /usr/local/medialibrary/bin (or wherever your original ffmpeg was located)
cp ffmpeg /usr/local/medialibrary/bin/.
Restart the Roon Core
Hopefully should now play AAC files. If you have any issues, rename ffmpeg_OLD back to ffmpeg again.
It looks like the QNAP installed version of ffmpeg has been compiled with most of the decoders disabled so hopefully they will fix this soon.