You seem like a smart bunch, so hopefully someone here will understand what is going on. I have a bunch of AVI files that I'm trying to convert to MP4. All but 5 or 6 of them convert fine, but those 5 or 6 all have the same problem. Despite the fact that there appears to be nothing wrong with the AVI file and it will play fine on my PC, the converted MP4 has an audio sync problem that gets progressively worse as the video continues, until the video is a full 2 seconds ahead of the audio (minimum, I haven't timed it with a stopwatch or anything). I've used 3 or 4 different converters and they all produce the same results or worse, produce a file that simply doesn't work. Anybody run into anything like this and know how to fix it?

BTW - Yes, I know Google is my friend, but today it isn't. All my searches produced what looked like promising answers, but frequently led back to things I had already tried or spyware/adware filled crapplications.

Are you able to set audio interleaving while converting the files? If you do a conversion with only streaming audio, there is often a sync error. Even if you set the interleaving to something rather infrequent, it is usually enough to rectify the error.

That is really all I can think of, off the top of my head, other than there being errors in the original file.

Edit: I Googled to make sure I wasn't giving bad advice. It seems what I was referring to is primarily used for converting to avi files, not from, in Virtualdub. Most of my experience is coverting from other file formats into avi files, so I apologize in advance if my advice isn't applicable.

What app are you using? If you have Adobe Premiere, it will make the task a lot easier. If using Virtualdub, I think you can extract the source audio file, cut it here and there manually until it syncs up with the video, then compress it back together with the video.

What exactly are you trying to do? Because converting AVI to MP4 isn't telling anything useful since they are both container formats and can contain almost anything.
What codecs are used in source and output? Is the source using variable frame rate? Use MediaInfo to get the information if necessary
What converters are you using?
Also does it have to be in MP4 container? Matroska is more versatile and supports adjusting timecodes of a track to fix linear drifts.

I'm not that advanced. I was using Handbrake (the only tool I was familiar with from converting DVDs to MP4), but I also tried several freeware "AVI to MP4" and "AVI to PS3" converters. Handbrake produces the useless file, the others produce the file with the sync problem. I'm trying to convert from AVI to MP4, that's it. I have AVI files (DivX, I'm reasonably certain) that are not very portable and I need them in MP4 so I can do things like play them on my PS3 (no other format/container works as well as MP4 on as many devices). I have no idea what the output codec is, I don't even mess with those settings or even have settings like that available in the tools I am using. Yes the source was variable frame rate, but I have tried encoding in a fixed frame rate (ensures greater compatibility with the devices I use) and a variable frame rate, the results are always the same. The problem is, the source does not have this issue at all, only the output file does. I have not tried that one yet, I'll give it a shot, thanks!

You're welcome, I started using it when Sony Vegas Pro 8 was giving me quality problems with downsizing. Trial and error attempts to fix the quality took hours and never really gave me the quality I expected. A friend suggested this program which worked like a charm.

That did the trick. For some reason, the files are still not playable in WMP, but I can play them in VLC and on my other devices, which was the whole goal of this project in the first place. There does seem to be some artifacting introduced into the video, but I think I can work around that by tweaking some settings. The original files weren't that great to begin with (old TV episodes recorded in SD years ago) so I might just put up with it. Thanks again!

Glad to hear it works for you as well. Seems I only needed to change the frame size when I used it. I also have found ConvertXtoDVD to be a very handy program for archiving to SD DVDs.

I don't remember where I found my copy but the program will allow you to convert your videos to DVD with a nice menu. I would think this would be great for a TV series. I've only used it to convert my Canon .mov files to DVD's having a menu for the videos by event (Thanksgiving, Xmas, Easter, etc)

If you search you can find sources for the program or follow the link above to the dev site.

What is WMP and what is it used for????? ; P

Edit: The .mov files are HD but the conversions look great in SD. Relatives think they are HD . . . =)

After converting to DVD format I burn the actual DVD with Nero.

WMP = Windows Media Player. It really does nothing useful, it was just an easy way to test the converted files.

I'm actually trying to get away from DVDs entirely. I have all my commercial DVDs (except a few that have really pesky copy protection) archived to MP4s that are served up by a media server to all the connected devices in my house. The only things I had left to work on were my recorded TV episodes which were surprisingly much harder to deal with than the commercial DVDs.

Just kidding about the WMP, I pretend it doesn't exist . . . on second thought, it doesn't for me . . . = D

Definitely much better than DVD's, good luck with the rest of your conversions. Hope the tweaks work on the artifacting.