Hi,
If you can see preview through autovideosink. The source should work. There are related topics:
IP camera connection with jetson.utils.gstCamera - #6 by dusty_nv
Passing in codec options to jetson.utils.videoSource in python - #4 by dusty_nv
jetson.utils.videoSource() and RTSP with low latency on Nano - is it possible? - #3 by dusty_nv
Please check and see if these help.