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.
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. |
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.