Different ends you need to know.

    RF end is very common, such as cable lines connected with TV. 
    The two pictures aside are the ends of our 2-in-1 wire. The left picture is connected with a camera or a microphone, and the right one is connected with  host (DVR or  DVR-card at PC).

* AC= Alternating Current
* DC=Direct Current

To security camera:

Right=RF positive end.

Left=DC  positive end.

To host:

Right=DC negative end.

Left=RCA (AV) positive end.