Jerky/stuttering capture

andy

I would be very grateful if anyone can give me useful input, insight or even a hunch on what might be causing my capture problem outlined below.

I am experiencing very jerky and stuttering video capture using Virtualdub. Previously my captures have been fine. I should emphasise that I am getting virtually no dropped frames reported.

I have tied a number of different capture environments :
384x576, 25fps, Huffyuv
384x576, 12.5fps, Huffyuv
384x576, 25fps, Mjpeg
384x576, 25fps, divx3.11_fast@6kbits
384x288, 25fps, Huffyuv

They all exhibit the same problem - and usually in the same places/scenes of the video.
I also tried to capture from SVHS and VHS material - same result.

The fact that I massively reduced the capture format implies that the problem is not due to CPU bandwidth. I believe it has something to do with the capture driver/card not being able to cope with the analogue to digital conversion quot;smoothlyquot;.

Setup:
PC : Win2k, Asus A7V, Athlon 800, 128Mb RAM
HDD : IBM deskstar 60Gb, 7200rpm, NTFS, used solely for video capture
Capture card : BT848 based Hauppauge WinTV PCI, using Composite I/P
Video source : SVHS-ET recording of Digital cable broadcast, i.e great picture quality source material

Differences to system since last successful capture (that I can remember) are :
Installed Norton Antivirus 2003 - disabled when capturing
Reinstalled the latest Hauppauge VFW WinTV drivers for Win2k
Have a flash memory reader/writer connected but disabled.

Things I haven't yet tried :
Turn off VCR noise reduction
Try another capture application
Try using WDM drivers instead of VFW

Thanks for taking the time to read this !

For anyone interested this thread is getting more attention at the unofficial virtualdub forumhere