Follow are some reasons i know: 1 The original video file is unsync 2 your ac plugin is too old 3 The original file has mosaic or broken frame 4 use avs to compress the video files which audio are two channels above Above are something i know, maybe there are some other reasons. You can refer here for some tips to fix the unsync problems. http://www2.dvd-ripper-copy.com/forum/viewtopic.php?t=192 I wish it is useful to you
