I still need do some debug,but I just know How to modify gst nvinfer, first you need to read the info that bcao mentioned, then check the code:
and
the first one is preprocess for frame infer,the second one is for object infer.
all those function called a func named “convert_batch_and_push_to_input_thread” this func is used to do preprocess async.
pls read " DeepStream SDK FAQ" to understand some background info.