In the link of my first post here:
So you would do (using -v with gst-launch will show the caps at each plugins ends) so you can see what is the resolution at nvvidconv output (src) :
gst-launch-1.0 -v nvarguscamerasrc ! 'video/x-raw(memory:NVMM),width=3864,height=2180' ! nvvidconv left=1692 right=2172 top=900 bottom=1280 ! 'video/x-raw(memory:NVMM), width=480, height=380' ! nvegltransform ! nveglglessink window-width=480 window-height=380