Important:
This is retired content. This content is outdated and is no longer being maintained. It is provided as a courtesy for individuals who are still using these technologies. This content may contain URLs that were valid when originally published, but now link to sites or pages that no longer exist.

A version of this page is also available for

4/8/2010

This is an abstract base class from which all filters are derived.

It supports the Component Object Model (COM) IBaseFilterinterface and is derived from the CUnknownclass. This class supports the enumeration of pins by calling the pure virtual member functions CBaseFilter::GetPinand GetPinCount. These member functions must be overridden by any derived class.

The CBaseFilterclass assumes that all the filter's pins are derived from the CBasePinclass. CBaseFilter::GetPinmust return a pointer to CBasePin.

All member functions in this class that return HRESULTand accept a pointer as a parameter return E_POINTER when passed a null pointer.

Protected Data Members

Member	Description
m_clsid	Class identifier (CLSID) used for serialization using IPersist.
m_pClock	Filter graph's reference clock.
m_pGraph	Pointer to a graph to which this filter belongs.
m_PinVersion	Current version of the pins used on the filter.
m_pLock	Pointer to the critical section used for locking.
m_pName	Filter name.
m_pSink	Pointer to the IMediaEventSinkinterface on the filter graph manager.
m_State	Current state: running or paused.
m_tStart	Offset from the stream time to the reference time.

Member Functions

Member function	Description
CBaseFilter	Constructs a CBaseFilterobject.
GetFilterGraph	Returns the filter graph associated with the filter. This is used in the implementation of CEnumPins.
IncrementPinVersion	Adds 1 to the pin version stored in m_PinVersion.
IsActive	Determines if the filter is currently active (running or paused) or stopped.
NotifyEvent	Sends an event notification to the filter graph.
ReconnectPin	Requests pin for a reconnect.

Overrideable Member Functions

Member function	Description
GetPin	Returns a pointer to the requested pin.
GetPinCount	Returns the number of pins currently available on this object.
GetPinVersion	Returns the current version of the base filter for comparison with the version with which the pin was initialized. This member function can be overridden if pins are being created dynamically.
GetSetupData	Retrieves the registration data associated with the filter.
StreamTime	Returns the current stream time.

Implemented IPersist Methods

Method	Description
GetClassID	Returns the class identifier of this filter.

Implemented IMediaFilter Methods

Method	Description
GetState	Retrieves the current state of the filter.
GetSyncSource	Retrieves the current reference clock in use by this filter.
Pause	Instructs the filter to transition to State_Paused state.
Run	Instructs the filter to transition to State_Running state. Passes a time value to synchronize independent streams.
SetSyncSource	Informs the filter of the reference clock with which it should synchronize activity.
Stop	Instructs the filter to transition to the State_Stopped state.

Implemented IBaseFilter Methods

Method	Description
EnumPins	Provides an enumerator for this pin's preferred media types (implemented by this class).
FindPin	Retrieves the pin with the specified identifier.
JoinFilterGraph	Notifies a filter that it has joined a filter graph (implemented by this class).
QueryFilterInfo	Gets information about the specified filter (implemented by this class).
QueryVendorInfo	Retrieves optional information supplied by a vendor for the specified filter.

Implemented IAMovieSetup Methods

Method	Description
Register	Adds the filter to the registry.
Unregister	Removes the filter from the registry.

Implemented INonDelegatingUnknown Methods

Method	Description
NonDelegatingQueryInterface	Passes out pointers to any interfaces added to the derived filter class.

Requirements

Windows Embedded CE	Windows CE 3.0 and later
Windows Mobile	Windows Mobile Version 5.0 and later
Note	Microsoft DirectShow applications and DirectShow filters have different include file and Library requirements For more information, see Setting Up the Build Environment © 2010 Microsoft Corporation. All rights reserved.