use a program to extract the sound from your movie as a mp3.
sequence using that mp3. when you save you get a fseq rendered file.
if running your show from FPP you send the fseq and the mp4 (not the mp3) to the FPP. It plays a movie, sound from movie comes out audio port, fseq drives lights.
FPP constantly checks and keeps lights synced to movie.
if playing show from xlights, it is not as exact.
u sequence and produce mp3, mp4 and fseq
now schedule the mp4 and fseq file. Just note that xlights launches a video player and starts the mp4 when your sequence starts. it does not adjust playback so there might be a slight offset by end of playing
I havent used xlights to play my show since 2012. i used FPP in 2013,2014 and again this year. It just is a more powerful show scheduler.
Very easy to get running. Buy whole hardware from amazon
http://www.amazon.com/CanaKit-Raspberry-Complete-Original-Preloaded/dp/B008XVAVAW
just add a 32gb usb flash stick to store your sequence data and follow instructions from
http://falconchristmas.com/forum/index.php/topic,483.0.html
less than 1 hour, you be playing your sequences from a FPP.