There are a bunch of sketches you can use on the Arduino. I prefer the version that turns the Arduino into a Renard device (Renard does NOT imply separate channels, just look at the PX1). Many people like to use a "Generic Serial" based sketch. Either way, you end up with a serial link from the show player to your Arduino. The serial link will use either RS-232 (short distances 0-5M) or RS-485 (longer distances >5M). You can find sketches in various conversations here on the Forum. Many believe the "Generic Serial" is easier to use but then forget that there needs to be a sync mechanism between the Show Player and the Arduino. The Renard protocol has that built in and is rock solid. Generic Serial uses a "Header" sequence of characters you set (and compile in) to gain sync. It is easily lost so you have a higher chance of flicker using generic serial.