VC_GetOverlayMode

ULONG
VC_GetOverlayMode(
VCUSER_HANDLE
vh
);

The VC_GetOverlayMode function requests a kernel-mode video capture driver to return the device's overlay, color keying, and decompression capabilities.

Parameters

vh

Handle to the kernel-mode driver, obtained from VC_OpenDevice.

Return Value

Returns an unsigned long value containing flags that indicate the types of overlay capabilities supported by the hardware. Zero indicates that overlay is not supported. A nonzero return value can contain the following flags.

Flag Definition
VCO_KEYCOLOUR Indicates the device supports a key color.
VCO_KEYCOLOUR_FIXED Indicates the key color cannot be modified.
VCO_KEYCOLOUR_RGB If set, indicates the key color must be specified as an RGB color. If clear, indicates the key color must be specified as a palette index number.
VCO_SIMPLE_RECT Indicates the device supports a single rectangular overlay region.
VCO_COMPLEX_REGION Indicates the device supports a complex (multi-rectangle) overlay region.
VCO_CAN_DRAW_Y411 Indicates the device can display bitmaps that contain YUV 4:1:1-formatted data.
VCO_CAN_DRAW_S422 Indicates the device can display bitmaps that contain YUV 4:2:2-formatted data.

Comments

The VCO_CAN_DRAW_Y411 and VCO_CAN_DRAW_S422 flags indicate the types of compressed formats the hardware supports for playback by means of the VC_DrawFrame function.

The VC_GetOverlayMode function calls DeviceIoControl (described in the Win32 SDK) to send an IOCTL_VIDC_OVERLAY_MODE control code to the specified kernel-mode driver. When a kernel-mode driver using VCKernel.lib receives this control code, its GetOverlayModeFunc function is called.