I have removed the inference from python test app deepstream_test_1_usb.py it works until is swap the source from v4l2src to nvv4l2camerasrc. With nvv4l2camerasrc I get same error relating to the number of surfaces
I have looked to see if this error appears elsewhere on the forum:
Appsrc with numpy input in Python - Intelligent Video Analytics / DeepStream SDK - NVIDIA Developer Forums
but none provide a solution