Audio out of synch with some players

[striperslayer59]

I had successfully converted several avi files to dvd using avi2dvd. Then suddenly with several similar files the audio is out of synch when I play the original avi files with Roxio Powerdvd or Windows Media Player. They are in synch when played with DivX player. When I convert to dvd format I have the same problem. I have tried to read up on audio streams and avisynth etc but it is way beyond me at the point in my dvd development. Can anyone enlighten about what the problem is an a relatively simple solution?
Thanks
striperslayer

[Matthew]

It's possible that the files contain an audio delay.

When an audio delay is specified in Nandub/virtualdub/virtualdub, it is achieved by inserting 0s at the top of the audio stream. avi converters typically won't account for this - the 0s are simply ignored as it is junk data. AVIMux GUI will tell you the delay (if there is one) or you can extract the audio and view it in a hex editor.

[striperslayer59]

Mathew, Thanks for the reply. I will try that approach,but I still don't understand why the delay only occurs with Powerdvd and Windows media player and Not DivX. DivX plays the avis fine. I think my problem is that I have very poor understanding of Codecs and how they work. Is there a guide that explains all about codecs? I don't know if each program uses its own or is it the avi file that determines which codec is used. Also when a new codec is installed does it replace an old one or are both available? I feel like I'm rambling now but I went off on that tangent because I believe that this problem started when I upgraded a codec in response to an avisynth error message. The upgrade solved the Avisynth problem. but coincided with the audio out of synch problems as well. Could someone point me to a guide that
explains the basics of codecs?
Thanks for any help
Chuck

[Matthew]

Codec issues aren't necessarily easy to diagnose/fix, short of uninstalling all of them, installing only the essentials, and crossing one's fingers.

Anyway, it's a process of elimination - deal with the most obvious and easy thing first. If a conversion to dvd is out of sync then the most obvious candidate is the avi. It's also the easiest issue to look at (IMO), and so the first thing that should be ruled out.

In a dvd conversion, the audio itself is not going to be affected by codecs in the normal course. This is because the audio stream is extracted from the avi and re-encoded independent of any codecs. Assuming this is what avi2dvd does.

That leaves the video somehow getting botched up...and even with codec issues you probably shouldn't be experiencing dropped frames.

If you still have one of the old successfully-converted avis, and it now converts badly, then that would rule out the avis being the problem.

[striperslayer59]

The audio an video of the original avi's are fine if played on DivX player but not with powerdvd or Windows media player, that seems to me to eliminate the avi's as the problem. Am I wrong?
Chuck

[Matthew]

That's a possible indication, but especially given that conversions are failing I wouldn't consider it enough to eliminate the avi as the source of the problem (e.g. the avi is strange in some way, and some software players do not like this).

But if you have decided that it's a codec issue the general advice is uninstall them all, and install only the ones that you need, not everything under the sun.

[setarip_old]

@stripeslayer59

Hi!Then suddenly with several similar files the audio is out of synch when I play the original avi files with Roxio Powerdvd or Windows Media Player.What software, codecs, and procedures did you use to create these "similar files"?

[striperslayer59]

Setarip_old, Thanks for the interest. Unfortunately I can't answer your questions (edited redundant information), I don't know what I have for codecs on my system. I don't know where they come from, how they get here or how to tell which ones I have or which programs use which. Is there a guide that would enlighten me a bit. So far my knowlege is limited to the Doom9 Glossary. Other parts of the forum discussing codecs that I have searched , talk way over my head.
Mathew, I'm not decided at all that its a codec problem as I don't know enough about codecs or avi's to be decided about anything. I think I started that line of thought based on the experience that updating Window my Windows media player led to getting a codec error message when trying to play most of my avi's that played fine on the old version (and still play fine on the older version still on my laptop. I will try to f/u on your suggestions and examine the avi's.
Thanks
Chuck