Coonverting AVI to VCD - audio sync problem. Help!

[DPolwarth]

Hi!

I have an AVI file that I am trying to convert to a VCD. The AVI file plays back with the audio in perfect synchronisation under Windows Media Player. However, after I have re-encoded it in TMPGEnc I find that the sound is out of synchronisation in the VCD file.

Although I am a total newbie, I have had a look around on the forums to see if anyone else has the same problem, but so far no luck. I did find out some audio sync problems that may be related, but I'm not sure. I have not removed any bad frames from the file (I don't know how to) so the audio sync is not spoiled by that. Another common problem seems to be a gradual loss of sync due to a problem in non-standard fps encoding. However, in my case the loss of sync is about 10 minutes into the file, which seems to be quite soon for a gradual loss of sync.

I have of course tried ripping the sound in VirtualDub as a .WAV file, then re-encoding it again with this as the audio source. This does not work either, though I thought it would. As an experiment, I even tried re-encoding it as an SVCD file as opposed to a VCD, and experienced the same problem.

I'm at my wits end. As a newbie, I have had to learn a lot in a short time, and it has overloaded my brain. But I can't get past this particular hurdle. Can anyone offer their experience as to why this may be happening, and how I can correct it?

Thanks,

Daniel

[Solarjetman]

Here is a guide
https://www.videohelp.com/forum/userguides/140540.php

[mats.hogberg]

if anyone else has the same problem, but so far no luck.

?? This is the single most common question on this forum, I'm pretty sure!

I have not removed any bad frames from the file (I don't know how to)

Well, this is your problem, most likely. Specially downloaded AVIs have lots of errors, and really have to be cleaned before doing anything else. Use VirtualDub MP3 Freeze to scan for and remove bad frames. That the AVI plays fine in WMP (or other player) doesn't make it a working source fro conversion.

/Mats

[Solarjetman]

?? This is the single most common question on this forum, I'm pretty sure!

LOL, I was too hesitant to say that

[DPolwarth]

Thanks guys! I'll give that a try and let you know how I get on :P

[DPolwarth]

Hmmmm. I just checked the source file out with VDub mp3 freeze, and it found no bad frames. So I guess that rules out the bad frames theory.

Given that there is not a problem with the file itself, I assume the re-encoding is hitting a problem elsewhere. Could this be due to the dreaded 'gradual loss of sync' problem caused by a non-standard source file?

I looked at the guide you suggested that recommended I change the pitch of the sound file to match. Do you think this is the solution to the problem?

Dan

[mats.hogberg]

Hm...

in my case the loss of sync is about 10 minutes into the file, which seems to be quite soon for a gradual loss of sync

This still leads me to believe that it's a problem in the source - Try frame serving from VirtualDub to TMPGEnc.
Gradual desync problem starts at the very beginning (and keeps getting worse thru the whole movie, a little worse each frame), so 10 minutes into the movie isn't "quite soon". It's all a matter on your sensitivity, how soon you notice it.
Gradual sync loss is usually due to the source and dest frame rates aren't the same.
Sudden loss of sync (the movie is in sync for a while, and then suddenly is no more, often accompanied by some visual garbage) is usually due to an error at some point in either video or audio stream, of which the video stream is almost always the culprit.
So, I'm not sure what you're describing really.
If you play the mpeg (before authoring to VCD), does it play nicely, or is it the same problem on your computer too?

/Mats

[DPolwarth]

The loss of sync does occur about 10 minutes in, it seems. Prior to that there is no dialogue, but there does not appear to be any problems with the sound at the beginning that I noticed. After about 10 minutes in, there is some dialogue in which the audio is about 1 or 2 seconds out of sync, and it is quite noticable.

On the VCD version, there was quite a bit of garbled image at one point, with big 'digital' chunks appearing to be corrupting the screen. Its possible that there may have been a problem then that led to the sound going out of sync.

When I play the original source image back in windows media player, the sound is in perfect synchronisation. This is why it is hard for me to figure out exactly the reason for this problem. It really has me stumped.

Try frame serving from VirtualDub to TMPGEnc.

What does this mean exactly? I'll give anything a try if it could solve the problem. Remember I'm new to this, so could you explain it for me?

Thanks for your help so far,

Dan[/quote]

[mats.hogberg]

Try frame serving from VirtualDub to TMPGEnc.

There are ready made guides for this at this site.

When I play the original source image back in windows media player, the sound is in perfect synchronisation. This is why it is hard for me to figure out exactly the reason for this problem. It really has me stumped.

Like I said before: That means nothing in respect to how error free the AVI is.

On the VCD version, there was quite a bit of garbled image at one point, with big 'digital' chunks appearing to be corrupting the screen

There you go! This is 99.999% due to an error in the source AVI.
Try aving out a 2nd copy of the AVI with VirtualDub, using direct stream copy, and use this for the rest of your work.

/Mats

[ZippyP.]

On the VCD version, there was quite a bit of garbled image at one point, with big 'digital' chunks appearing to be corrupting the screen

There you go! This is 99.999% due to an error in the source AVI.
Try aving out a 2nd copy of the AVI with VirtualDub, using direct stream copy, and use this for the rest of your work.

I absolutely agree with Mats because Vdub does not always catch all the bad frames when scanning a video file. If you know where the desync occurrs then you can edit out that section of the avi manually using Vdub. Mark the bad chunk and delete it, then save the new file. Check the Edit section for a Vdub guide.