Hi , i would like to implement this function: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/multimed/ht... Here fpProc is a pointer to the preview callback function Applications use this to get access to the videodata. Right now i already have a preview window. If i'm correct it is similar to this function:http://msdn.microsoft.com/library/default.asp?url=/library/en-us/multimed/ht... Here the structure LPVIDEOHDR lpVHdr contains the information about the videodata. My question is how all of this could be implemented; right now i have : case WM_CAP_SET_CALLBACK_FRAME: LPVIDEOHDR lpVideoHdr; //defined in vfw.h typedef LRESULT (CALLBACK * CAPVIDEOCALLBACK)(HWND hwnd, LPVIDEOHDR lpVideoHdr); CAPVIDEOCALLBACK *framecallback = (CAPVIDEOCALLBACK *)lParam; {so what goes here? } return TRUE; break; So how could i pass the data in lpVideoHdr to the application? Any help appreciated as i'm still quite a beginner in this :) Regards Send instant messages to your online friends http://uk.messenger.yahoo.com