What a good Video Interface for X5 E53 4.6is ?

[Txlee]

Dear Dudes,

My car is X5 E53 4.6is of year 2002, with 16:9 Navigation Wide Screen Car Monitor at front console, CD Changer at side trunk, Radio/ Sound Module + DSP Amplifier/ Video Module are under the trunk.

I am going to install
(a) Gateway 300 to have iPod musics through the audio system
(b) Reverse camera

Pls adv what a good and affordable Video Interface or Converter suitable for my case in order to have different audio and video sources on the original car monitor
I maybe have video source from iPhone to have Youtube or DVD other than just iPod and CD musics

Thx in advance