Hi all!

This might be a thoroughly simple question, but as I am unable to formulate it in a simple sentence, Google cannot really help me.
Since I will soon be buying a place of my own, I have certain desires which are of a geekier nature. A friend will be renting a room from me, and we both like music a lot. I will be installing a simple computer which will be connected to the TV and audio-equipment. But for basic control of the music or video (play/pause, next, back, mute/unmute, volume) I would like to be able to do this without using a remote or a keyboard.
So... I figured that since there are major programming incompatibilities, and there is also the Apple Store to take into account for installing the app, the best way would be by webcontrol.
However.. Which language would allow me to run both on the Iphone, as well as Android? What my current setup would look like is this:
A program or webpage running on the HTPC. Connect the phone through WiFi to either the program or the webpage. Press an available button/move a slide. The HTPC handles the input accordingly.

What would be the best option to code this in?

(P.S. for the sake of information, Winamp and VLC will be run most of the time)

Anyone have a clue?
If someone could just point out which language is best to use, I would be able to manage from there