leeson

if the whole OS is no longer on a SD card you can disable ramlog in /etc/default/armbian-ramlog.

@Arif Setiadi  the browser supports h264 direct playing at default，you can try 4k hevc ,it will  transcode from high vedio bitrate to low vedio bitrate when you chose low vedio bitrate ,and transcode from hevc vedio codec to h264 vedio codec

@StarboardOtter i had tryed with debian12,you need download the jellyfin client app, then add your server's ip or domain ,chose the quality as low, like this,it worked
here is the link for jellyfin client app https://github.com/jellyfin/jellyfin-media-player/releases .
In general, the Jellyfin client app works by utilizing your client device's GPU for transcoding when your client device's GPU is supported (direct play).
Otherwise, it uses your server device for transcoding.
Sorry, my English is not very good. I hope this helps.

@Arif Setiadidocker image is server , client app you need download form https://github.com/jellyfin/jellyfin-media-player/releases  

@LoneExile
This is my process：
I used 5.10.x kernel, which was already there when I installed the system as @nyanmisaka he said，download the OpenCL，then use  sudo apt install ./libmali-valhall-g610-g13p0-x11-wayland-gbm_1.9-1_arm64.deb  
docker run -d \ --name jellyfin \ --privileged \ --net=host \ --restart=unless-stopped \ --volume /path/to/config:/config \ --volume /path/to/cache:/cache \ --volume /path/to/media:/media \ --device /dev:/dev \ nyanmisaka/jellyfin:latest-rockchip  
maybe need  chmod 777 -R /dev （i'm not sure to run it yes or no）