v4l2 format conversion

Hello Dear community,
I will appreciate your opinion regarding the question below.
THanks in advance.

I need an app that uses v4l2 to capture frames from webcam.
the app needs to process (un compressed !!!) 4k frames with 30fps.

according to v4l2-ctl, to get 4k frames with 30 fps, camera requires MJPEG
files (compressed).

That means MJPEG files has to be converted to raw files (eg, RGB).

question is:

   1. is there any way to configure v4l2 do the conversion for me
   or do i have to write special code to do the conversion ?
   2. if i have to write special code to do the conversion,
   is there any recommandation how to do it efficently ?(i an working with
   Orin)