Hi,
Please check you have executed dGPU Setup in
https://docs.nvidia.com/metropolis/deepstream/dev-guide/index.html
And try test-luanch:
See if you are able to launch
./test-launch "videotestsrc ! x264enc ! h264parse ! rtph264pay name=pay0 pt=96"
And
./test-launch "videotestsrc ! nvvideoconvert ! nvv4l2h264enc ! h264parse ! rtph264pay name=pay0 pt=96"