What's the deal with audio sync and frame drops?

[xjapan89]

When you capture with audio sync it's easier to get dropped frames, right? why is that? Is there a way to solve that? I really would like to use VirtualDub to capture my videos, but I always get dropped frames with it. Other tools, like the old VidCap from microsoft, gives me no drops, but the audio is often out of sync and the frame rate never comes out exacts 29.97 fps...
Well, thanks for the attention!

[Greg12]

I'm not sure but i would imagine to keep audio sync, virtual dub trashes frames.

Also some may be dropped in other places.

Do u have PCI or AGP or USB?

USB drops frames right and left.

[sommersby]

You will always drop frames when snycing the audio, a few dropped frames an hour is normal and good, otherwise your audio would get more and more out of sync.

[Greg12]

Their's something in some high end VCR's that adds a sync pulse that i've heard can reduce dropped frames and help with hard to sync captures.