VirtualDUB always drops frames when capping.

[Red Hat]

Whenever I cap at 640x480 in virtualdub in Huffyuy frames always drop. Frames don't drop at all when I cap in Virtual VCR with the same settings. Any ideas why?

[gll99]

vdub is a vfw app
virtual vcr is a wdm app

When you cap with vdub with any win nt based os like winxp, you are going through a nt vfw2wdm filter written by ms. This filter/translator is slow and can be buggy which leads to errors. Vdub is a great app but the base code was written for win95 and win98 vfw (vxd) drivers.

I use vdub for many things but not capturing.

Don't take that as a knock on vdub it's just the reality as documented by the author.

btw) This is how it shows up in your system devices:
Microsoft WDM Image Capture (Win32)
and this is the actual filter/wrapper dll name which is usually in the system32 directory:
vfwwdm32.dll

[zedolfblack]

When i capture with VirtualDub i use this method...

First i get all the resolution and capture codec settings (etc) as i want them.

Then i do a 60 second test capture.

On the VirtualDub capture panel you'll see Avg frame size and it'll report the average frame size for the test capture.

I then use the Disk I/O setting on the Capture menu.
I set the Chunk size so that it's larger than the average frame size and the Chunks in buffer to a value higher than the framerate that i'm capturing at - in fact i generally set Chunks in buffer to 32.

Can't swear that it'll fix your problem but by my way of thinking it'll do no harm!

Martin.

[SatStorm]

Try to capture at 352 x 480 or 704 x 480

[Red Hat]

Problem sloved. Thanks everyone.

[junkmalle]

Problem sloved. Thanks everyone.

What was your solution?

[Red Hat]

I changed my chunks and unchecked everything in capture sync and choose do not resync between audio and video streams. Here's a sample of something I capped and encoded in vdub.
http://pranksnfiles.com/crow/SampleCap.avi