HELP audio-video sync problem when playing psx bust a move/bust a groove

Im using retroarch version 1.3 on my jailbroken iphone 5 ios 8.1

I have no other issue except when playing bust a move 1 & 2 or bust a groove 1 & 2 it seems after a couple of seconds, the audio-video sync becomes more and more out of sync to the point of the said game becomes no longer playable

I havent tried messing with the settings as im afraid i might ruin my installed retroarch

but does anyone out there know how to set retroarch in such a way that the audio-video will be perfectly sync to play the said games.

Thanks a lot

what platform or core for bust a move!! and did you try other games on same coreā€¦