Caddy and Authentik play very nicely together thanks to caddy forward_auth
directive. Regarding acls, you’ll have to read some documentation, but it shouldnt be difficult to figure out whatsoever. The documentation and forum are great sources of info.
Correct me if im wrong, but if you play a 1080p video on a 4k screen, that would be upscaled. If you put a 1080p video in a 4K stream, then play that 4k stream on the 4k screen, no post-processing would be applied to the video on the screen. All the upscaling happens during encoding, where you have far more control over the upscaler quality.