To attach user-specific metadata at the batch, frame, or object level within NvDsBatchMeta, you must acquire an instance of NvDsUserMeta from the user meta pool by calling nvds_acquire_user_meta_from_pool(). (See sources/includes/nvdsmeta.h for details.) Then you must initialize NvDsUserMeta. The members you must set are user_meta_data, meta_type, copy_func, and release_func.

For more details, see the sample application source code in sources/apps/sample_apps/deepstream-user-metadata-test/deepstream_user_metadata_app.c.