whitebmw22

hi, i am looking to find out where i can get 12v constant power and 12v ign or engine power, i have tvs in headrests and dvd player up front these have the wires ready but not sure where i can get power i dont want to run a wire to boot battery as i no there is a 12v ingnition wire for cig lighter sockets on fuse board, is there anything like this in the front? if so do you no where it is or pictures?