Nvidia gstreamer elements

Hi,

Yes, both utilize NVJPG hardware engine.

Yes, it is hardware DMA buffer(called NvBuffer). ON JP4.5 we have most plugins open source, you may take a look at the implementation. Source codes are in
https://developer.nvidia.com/embedded/l4t/r32_release_v5.1/r32_release_v5.1/sources/t186/public_sources.tbz2

Yes, please refer to steps in
Jetson Nano FAQ
Q: I have a USB camera. How can I launch it on Jetson Nano?