The capControlCallback function is the callback function used for precision control to begin and end streaming capture. The capControlCallback callback function is a placeholder for the application-supplied function name.
LRESULT CALLBACK capControlCallback(
HWND hWnd,
int nState
);
When nState is set to CONTROLCALLBACK_PREROLL, this callback function must return TRUE to start capture or FALSE to abort it. When nState is set to CONTROLCALLBACK_CAPTURING, this callback function must return TRUE to continue capture or FALSE to end it.
The first message sent to the callback procedure sets the nState parameter to CONTROLCALLBACK_PREROLL after allocating all buffers and all other capture preparations are complete.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in vfw.h.
Import Library: User-defined.
Video Capture Overview, Video Capture Functions