valley

Hey guys, I am kind of new in this area so bare with me . I want to install a cctv system with a camera which sends a wireless signal to a radio av receiver. This receiver then gives me an output of Audio and Video via RCA female ports. I would like to somehow hook these outputs up to a usb or external hard drive to capture all of the videos and audio transmitted. Do I need to have some adapter between the ports and the usb or do I need some sort of software? Any advice is welcome!!