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Extended Camera Control Payloads

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The control properties within the KSPROPERTYSETID_ExtendedCameraControl property set use a common payload format for getting and setting the property data.

Extended camera property header

All payloads begin with a KSCAMERA_EXTENDEDPROP_HEADER structure. This structure contains the PIN target with the associated control flags and capabilities. Depending on the particular control, the Capabilities member will contain a set of capabilities provided by the control. The Flags member will contain the actual capabilities currently set or to be set for the control.

The PinId member specifies the target which is either the camera PIN or the filter PIN. If the property is a filter level control, then PinId is set to KSCAMERA_EXTENDEDPROP_FILTERSCOPE.

A property control is either synchronous or asynchronous. If the control is synchronous, then the KSCAMERA_EXTENDEDPROP_CAPS_ASYNCCONTROL flag is set in Capabilities. Also, if the control is cancelable, the Capabilities member includes the KSCAMERA_EXTENDEDPROP_CAPS_CANCELLABLE flag.

The payload size is set in the Size member. The value for Size is the entire size of the payload. If the property uses only the header, then Size = sizeof(KSCAMERA_EXTENDEDPROP_HEADER). Otherwise, Size = sizeof(KSCAMERA_EXTENDEDPROP_HEADER) + sizeof(control specific data).

Control specific data

Some property controls use an additional structure to hold additional data. Where single data values are used, the property data will contain an KSCAMERA_EXTENDEDPROP_VALUE structure after KSCAMERA_EXTENDEDPROP_HEADER. The KSCAMERA_EXTENDEDPROP_VALUE structure allows the property to express a single value as one of several data types.

To get or set additional data, a property will have its own special data structure following the KSCAMERA_EXTENDEDPROP_HEADER. The following example shows a driver code fragment setting the property specific data for a KSPROPERTY_TYPE_GET request of the KSPROPERTY_CAMERACONTROL_EXTENDED_FIELDOFVIEW property.

#define FL_WIDE_ANGLE 35
#define FL_NORMAL     50

PBYTE Payload = (PBYTE)PropData;
PKSCAMERA_EXTENDEDPROP_HEADER ExtendedPropHeader = (PKSCAMERA_EXTENDEDPROP_HEADER)Payload;
PKSCAMERA_EXTENDEDPROP_FIELDOFVIEW ExtendedDataFov = (PKSCAMERA_EXTENDEDPROP_FIELDOFVIEW)(Payload + sizeof(KSCAMERA_EXTENDEDPROP_HEADER));

ExtendedPropHeader->Version = 1;
ExtendedPropHeader->PinId = KSCAMERA_EXTENDEDPROP_FILTERSCOPE;
ExtendedPropHeader->Size = sizeof(KSCAMERA_EXTENDEDPROP_HEADER) + sizeof(KSCAMERA_EXTENDEDPROP_FIELDOFVIEW);
ExtendedPropHeader->Result = 0;
ExtendedPropHeader->Flags = 0;
ExtendedPropHeader->Capability = 0;

ExtendedDataFov->NormalizedFocalLengthX = FL_WIDE_ANGLE;
ExtendedDataFov->NormalizedFocalLengthY = FL_WIDE_ANGLE;
ExtendedDataFov->Flag = 0;
ExtendedDataFov->Reserved = 0;