If you get error about opening device /dev/videoxx, try run following command to add user to group Video: sudo usermod -a -G video pi where pi is user name.
Function of LPUWS is similar to Theremino or Spectragryph software on Windows.
Video: LPUWS in action on Raspberry Pi or see it on Youtube.
Some screens:
LPUWS Spectro Meter SW is developed in Lazarus with 5dpo SdpoVideo4l2, "JBS Laz Version Info Library" and SpectraLibrary.