Related to this, I use this script to setup a live stream of my cameras on a debian system connected to a little monitor

https://gist.github.com/neontuna/d1ba0c771aa89c42910f21c0aae...

I didn't like having to fire up some NVR software just to get the camera live stream, and you're locked into whatever options that software might have. With ffmpeg you can do some cool stuff with filters.