VidCap problems

Hi,
I'm having trouble with the VIDCAP module in R4. I can capture video via a firewire port but the playback is very jerky and stutters badly every half second or so. Any suggestions as what could be wrong?
TIA.
I'm having trouble with the VIDCAP module in R4. I can capture video via a firewire port but the playback is very jerky and stutters badly every half second or so. Any suggestions as what could be wrong?
TIA.