I don't know if I can directly record a video from my dslr (lumix) to my computer (final cut pro x), in 4k.
I would like to avoid recording to an sd card (dslr) and then transfer to the computer. I would like to save time.
Anyone already tested this idea?
You can try to record in camera depending on the camera. Some cameras have limitations on live output and internal recording. Given you're sending nearly uncompressed to the computer that would likely be the best quality recording compared to an in camera compressed coded.
Bear in mind that you also have parts that can fail during a recording. If you are using HDMI connections, they're flimsy on all hardware. I can't count the number of times I've had HDMI connections fail because something got very gently bumped. There's a safety to SD cards that I think the extra time is worth.
Just out of curiosity, what exactly are you recording/editing in real-time? You may want to consider an ATEM Mini. Live switching saves tons of time. I've been doing live switching at the TV station for years and got an ATEM Mini Pro ISO simply to save me doing multicam edits. It takes some work to get the hang of, but worth the time spent.
But to edit files while recording in real-time, that is going to cost for that ability.