Accessing PGIE Tensor Inference Values from Nvds Tracker

[Amycao]

PGIE tensor data is stored in NvDsFrameMeta’s user meta. NvDsFrameMeta is not directly passed via NvMOT APIs, but can be accessed indirecly by the following steps.
(1) In nvdstracker.h, from NvMOTProcessParams access each NvMOTObjToTrack. NvMOTObjToTrack.pPreservedData is a pointer to NvDsObjectMeta of that input object.
(2) From NvDsObjectMeta.base_meta.batch_meta acquire NvDsBatchMeta for that batch.
(3) From NvDsBatchMeta acquire each NvDsFrameMeta’s frame_user_meta_list. That contains the PGIE tensor data.