Ipod Video's audio is out of Sync

When I convert some of my Avi's for the ipod the sound goes out of sync with the video.This is more noticible with longer files such as movies and the more you watch the more out of sync it goes.I have tried many different softwares including the imtoo's and Xilisoft's and many others.There are ways of getting the audio back into sync but this is a timely process which I didn't want to have to do after every conversion.

But I have recently been getting some good results with Jodix Free ipod converter.The software is 100% free and contains no ad's etc and it's simple to use.