(Pasted from my post in thread 7744)
Two common causes:
1. The person who encoded the video did a poor job. It’s not common, but it happens.
2. The computer you’re using is underpowered. Modern codecs (like divx, windows media video 9, h.264) take a lot of processing power to render video, and if your processor is old, frames will be dropped, audio and video will fall out of sync, the scene may seem to freeze. Video freezes more often, since video codecs take a lot more processing power than audio codecs. One easy way to check if you’re using Windows 2000 or XP is to look under your task manager. Right click your taskbar, then choose task manager. Look under performance. Is cpu usage at 100% while the video plays? if so chances are it’s choking on decoding the video. There’s not much that can be done except get a newer processor. You can also try to allocate as much cpu power to video playback by turning off and closing all unnecessary tasks (instant messengers, file sharing, anything in the taskbar, and (for advanced users only) services). Also disable post-processing and film effect if the file uses the divx codec. Finally another way to check if the processor is underpowered is using virtualdub. if the file plays in virtualdub in slow motion then your pc is underpowered. virtualdub is also a good way to view the movie without freezing/dropped frames (if you don’t mind slow-motion video and inaudible audio)
i have same problem, i record a tv show from tv adaptor usb, then cutting out the start and advertisments, then i join the files back together and the audio can be 10 mins out !!! i use SUPER VIDEO SPLITTER and SUPER VIDEO JOINER
Before you brake your piggybank try different players not only WMP.VLC and BSplayer are freeware and works better than WMP.Also classic media player has more codecs in it.About your computer besides a faster CPU the size of your RAM is a big issue when you’re dealing with video files and convertions.1GB of RAM became a standard if you want quality.Synch problems if your computer is fast enough come from conflicts between codecs so is a must to check the file before convertion with Avicodec or GSpot to find out the type of avi you have and the video/audio codecs you need.Here is a link to download codecs:http://www.free-codecs.com/
If you have an access to Macintosh, there is a step by step guide to fix the problem “Sound is out of Sync with the Video”.
Have you tried AVIMUX. Open File in AVIMUX, click on file and press generate data source from file. It will show you how many mseconds it is out of sync. press start and save file as(new name)It all over in 2 or 3 minutes and your film will be in sync 99% of the time. you can also enter your own figures manually. Just Google AVIMUX it’s free