VLC command line not using GPU

Hello, sorry if this is covered anywhere, I’m a first time poster here and really can’t find an answer.
I’m looking at moving some code that’s been running fine on Raspberry 3B+ / 4 to the Rock4c+.
I’m currently running the latest Debian image: rock-4c-plus-debian-bullseye-xfce4-arm64-20221109-1514-gpt.img
So i get the login, enter user: rock pass: rock and get the desktop
Then from an SSH window I issue the following command:
sudo -u rock XDG_RUNTIME_DIR=/run/user/1000 DISPLAY=:0 cvlc --loop --fullscreen --play-and-exit --no-osd --no-audio /home/rock/video.mp4
The video plays on the screen but you can see that its a little choppy.
Checking “htop” on the unit shows all 5 CPU’s in the 90% range so obviously using the CPU to do this work (and when stopped they all drop near 0%).
On the Raspberry PI4 (current test unit) doing the same video / process as above shows the video and a very low CPU.
What am I missing to get the Rock PI to use the GPU in this scenario please? Many thanks all.