[mythtv-users] some frontends wont play certain files

[Tim Draper]

i've deployed some rpi3's in my setup a few months ago and have noticed that all my avi videos wont play on all FE's.
the ones in question play fine on the rpi3's, but wont on my NUC (2820; celeron based).
I've not done much debugging on it yet, and only got as far as knowing that it's any avi i have. The few files i've checked seem to be xvid wrapped in avi container.
mpg, mkv, ts play fine across all FE's.

rpi3's are running jessie lite, with mythtv-light.
the NUC is running a mythbuntu 12.04 build.

is there something obvious i might of missed like a codec pack required on mythbuntu, before i get too involved in finding the issue?