VirtualDub: Dropping Frames in VirtualDubsynch
 

I'm using virtualDubSynch to resolve some A/V synch issues I was having with capturing from VHS.

I pass the hard drive test utility with flying colors, not a single frame drops. However, when I do the internal test or an actual capture I'm dropping anywhere between 15-40% of the frames. So for example, if I capture 200 frames, it says that 60 have dropped. When I use VirtualVCR I don't get any dropped frames, but I'm having other issues with that tool.

My settings are:
Huffyuv compression
44Hz Audio capture
29.976 fps
I've tried various disk IO settings

I've tried VirtualDub v1.5 & 1.6 beta, VirtualDubMod and VirtDubSynch with the same results.

Has anyone seen this behavior?

Does it happen only on VHS captures? If so, are the tapes LP or SP recorded?

It's happening on an EP recorded VCR tape and all so on an 8mm tape. I haven't tried other types of VCR tapes.

EP is bound to give you problems without proper equipment (a TBC, that is). 8mm might be the same. Capturing any videotape can be really painful because the signal is much weaker than in a regular TV broadcast, that's why you get dropped frames easily. With EP tapes the drops probably happen because the capture card doesn't get a good syncing signal due to the abnormal nature of LP/EP.

But how come if I use VirtualVCR or iVCR I don't get any dropped frames? If I do the 'test internal' off the capture menu, I also get dropped frames.

It seems like its some configuration issue with VirtDub, don't you think?

You use WDM drivers, right? VDub is a VfW program, which means that it works best with VfW drivers which are the ones that for example Win98 uses. WinXP uses WDM drivers.

Where I can grab VDSynch?

When will people learn to use Google before asking?

http://www.virtualdub.net

But you don't really need that one, the same function is in VDubMod as well.

Why you don't keep your bad taste comments for yourself.
Before I asked I do effectively a search
http://www.google.com/search?q=virtu...utf-8&oe=utf-8

http://www.google.com/search?hl=es&i...+synch&spell=1

Now tell me where in those sarch results see the word virtualdubsynch.

Please, never answer me again with that kind of answer. I prefer that you don't answer my question if you use those answers. I always do a search before ask for something.
Thank you.

Relax.

Your first Google gives no direct links, but I'm sure you know that people don't always spell everything correctly. That's why there is the "Did you mean: virtualdub sync" link which then would have given you the correct link.

Yes, that is the second one.
But I searched for a program called VirtualDubSynch, not for VirtualDub synch techniques, as I understood from second link results, then I did the question here.

Thinking about it, I don't understand why Google doesn't do the revised search without any user interaction if there are no results from the original search.. some search engines do that and it's sometimes very useful.

We've gotten a bit off topic here, so how about my last question:

But how come if I use VirtualVCR or iVCR I don't get any dropped frames? If I do the 'test internal' off the capture menu, I also get dropped frames.

Do you think its the driver is you aluded to earlier?

VM? DialHot? any thoughts?

The driver is probably the issue.

If you use WDM drivers with VirtualDub, it uses the card via a VfW to WDM wrapper. This can cause issues and does require more CPU power. Sometimes it doesn't work at all, in fact I never got WDM drivers working in VDub.

If you don't get dropped frames with VirtualVCR, why don't you use it? It has the dynamic audio resampling feature so it will keep the a/v sync just as VDub Sync.

I started off using VirtVCR but could never get the audio to synch. It would start off OK, but by then end of the movie be noticably off. Thats the reason I made the switch to VirDub-Synch, which does seem to work , except for dropping frames.

That's odd, are you sure you had the correct settings? Dynamic audio resampling enabled, no syncing by stream offset.

I'll give it another go.

There is a drop down that says 'master stream' in AVI file. Do you know what that is suppose to be set to?

You'll just have to try both ways, could be that 'Audio' works best. There's a forum for VirtualVCR, the link is at sf.net/projects/virtualvcr, you might find the best answers there.