When grabbing with either MdigGrab() or MdigProcess(), Matrox Vio is optimized to have the smallest latency possible between the last pixel sent from the camera to the last pixel written into the buffer (either on-board or to the Host). This allows the buffer to be available for processing with a minimum amount of delay.
By default, Matrox Vio grabs into off-board buffers. When grabbing into off-board buffers, if the acquisition rate is higher than the transfer rate across the PCIe bus, frames will be skipped rather than allowing a grab overrun to occur.
To be certain that no frames are missed when using MdigProcess(), use MdigInquire() with M_PROCESS_FRAME_MISSED. This value is based on a comparison between the frame rate (M_PROCESS_FRAME_RATE) and the frame count (M_PROCESS_FRAME_COUNT). If performing a triggered grab or if the hooked function is slow, this value will be affected. This value is most trustworthy with a camera in continuous mode.
Use M_PROCESS_FRAME_COUNT to determine the total number of frames grabbed in the sequence.
Use M_PROCESS_FRAME_RATE to return an estimate of the number of frames grabbed. Note that this value is determined based on the average of the camera's frame rate, and the total amount of time to process the user-defined hooked function(s). It might not be an accurate count of the total number of frames grabbed.