Buffer dropping in deepstream-nvdsanalytics c code running but the same python code works

Hi, I’m using Jetson Nano board, and I’m willing to use deep-stream,
I want to handle RTSP video stream using deepstreem-nvdsanalitycs.c, but it returns:
Warning from element nvvideo-renderer: A lot of buffers are being dropped…
And The RTSP video displayed has a constant frame dropping… but on the other hand the python script of the same sample works just fine.

You may refer to this patch:
Need help on adding RTSP support in nvdsanalytics example - #9 by DaneLLL