dpkg -S libffmpeg-nvenc-dev
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/include
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/lib/pkgconfig/ffnvcodec.pc
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/include/ffnvcodec/nvEncodeAPI.h
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/include/ffnvcodec
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/include/ffnvcodec/dynlink_loader.h
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/include/ffnvcodec/dynlink_cuda.h
libffmpeg-nvenc-dev: /usr/share/doc/libffmpeg-nvenc-dev/changelog.Debian.gz
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/lib/pkgconfig
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/lib
libffmpeg-nvenc-dev: /usr/share/doc/libffmpeg-nvenc-dev/copyright
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/include/ffnvcodec/dynlink_cuviddec.h
libffmpeg-nvenc-dev: /usr/share/doc/libffmpeg-nvenc-dev
libffmpeg-nvenc-dev: /debian/libffmpeg-nvenc-dev/usr/include/ffnvcodec/dynlink_nvcuvid.h
I would have expected them to just be in /usr/include etc.