KSFILTER structure (ks.h)

The KSFILTER structure describes an instantiated filter.

Syntax

typedef struct _KSFILTER {
  const KSFILTER_DESCRIPTOR *Descriptor;
  KSOBJECT_BAG              Bag;
  PVOID                     Context;
} KSFILTER, *PKSFILTER;

Members

Descriptor

A pointer to a KSFILTER_DESCRIPTOR structure that describes the characteristics of this particular filter.

Bag

This member specifies the KSOBJECT_BAG (equivalent to type PVOID) associated with this filter instance. Object Bags are structures used to associate dynamic memory with a specific AVStream object. Anything in the filter object bag is automatically cleaned up when the filter is deleted.

Context

A pointer that is used by the client to associate context information with the specific filter instance. Typically, such context information is associated in the filter's Create member as defined in the KSFILTER_DISPATCH table for this filter instance. Any dynamically allocated context information should be placed in the object bag with KsAddItemToObjectBag. Context is initialized to the value of the Context member of the parent KSFILTERFACTORY at the time the filter is created. See AVStream Object Hierarchy.

Remarks

Drivers implementing software filters typically associate filter state with the KSFILTER structure. Software filters usually process data within the callback specified by the Process member of the corresponding KSFILTER_DISPATCH structure.

Hardware filters typically do not use KSFILTER because the focus of the hardware driver is the platform transition: the movement of data between the host and the external hardware. This transition is typically handled by code associated with an AVStream queue object.

Also see Object Bags.

Requirements

See also

KSFILTER_DESCRIPTOR

KSFILTER_DISPATCH

KsAddItemToObjectBag

KsCompletePendingRequest