If you want to connect via RTSP to the MARS 400S Pro LAN-connected to your machine, you may connect to
rtsp://192.168.218.202:5554
for instance as vlc source sourced into OBS. :-)
But beware: RTSP delivered by the MARS contains alot of buffering, so a lot of delay. Its weak implemented, sometimes gets stuck or even breaks.
The way described by Tomasz is the really faster (and far more reliable) option. Even while the HDMI connection to the grabber brings additional delay and the ubs-grabbing part, too - it summarizes all to a shorter delay than the RTSP queueing.
So in conclusion the way going rtsp is the weakest solution (not to prefer).
