How to cut a frame into 4 blocks, and inference these 4 blocks parallelly as if there are 4 frames?

Is there any plugin to cut a frame into 4 blocks, and infer these 4 blocks parallelly as if there are 4 frames?

No. Current deepstream does not support such function.

Seems this topic is similiar to your case. Recombining nvstreamdemux output with nvstreammux fails - Intelligent Video Analytics / DeepStream SDK - NVIDIA Developer Forums