How to decode h264 with GPU(hardwatr decode) like 2080ti using gstreamer

how can I using the hardwatr-decode function to decode h264 with gstreamer?
when I install gstreamer in my pc, I can’t find the plugin like nvvidconv, nvv4l2decoder and nvvideoconvert?
Is there any way to install it?
the system of my pc is ubuntu 16.04, should I install a 18.04?