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.