BOOL
VC_Overlay(
VCUSER_HANDLE vh,
BOOL bOverlay
);
The VC_Overlay function requests a kernel-mode video capture driver to enable or disable the hardware’s overlay capabilities, using the current rectangle and key color settings.
Returns TRUE if the operation succeeds. Otherwise returns FALSE.
User-mode video capture drivers using VCUser.lib should call the VC_Overlay function with bOverlay set to TRUE when processing a DVM_STREAM_INIT command for the VIDEO_EXTERNALOUT channel. They should call the function with bOverlay set to FALSE when processing a DVM_STREAM_FINI command for the VIDEO_EXTERNALOUT channel.
The VC_Overlay function calls DeviceIoControl (described in the Win32 SDK) to send either an IOCTL_VIDC_OVERLAY_ON or an IOCTL_VIDC_OVERLAY_OFF control code to the specified kernel-mode driver. When a kernel-mode driver using VCKernel.lib receives one of these control codes, its OverlayFunc function is called.