Thank you all for your feedback. May be I should describe my application more. We have an ultrasound system here in the lab (University of British Columbia, Vancouver) and currently we are using a Matrox Meteor RGB frame grabber (PCI) to capture images in real-time through the composite video output and send them through a socket connection to a client to be processed in real-time again. There is no usage of hard drive here and also, we do not keep images in the memory after process. Question: If we would like to replace our board with a bt8x8 capture card, what are the functions we have available as a library to use the card? Does anybody know how different they are from Matrox? How could I have access to the specifications of V4L2 which are written for frame grabbers? Cheers, Purang