CBaseMediaFilter Class (Windows CE 5.0)

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This is an abstract base class that provides support for the IMediaFilter interface.

The CBaseMediaFilter class handles State_Stopped, State_Paused, and State_Running state transitions.

Typically, this class is used for plug-in distributors rather than filters with pins. Derive your filter classes from the CBaseFilter class (or base classes derived from this) instead of from this class.

All member functions in this class that return HRESULT and 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 Pointer to a reference clock used for synchronization.

The reference count of the clock object must be incremented using AddRef.

Pass NULL if no reference clock is available.

m_State Current state of the filter, which can be State_Stopped, State_Paused, or State_Running.
m_tStart Offset from the stream time to the reference time.

Member Functions

Member function Description
CBaseMediaFilter Constructs a CBaseMediaFilter object.
IsActive Determines if the filter is active (running or paused) or stopped.

Overrideable Member Functions

Member function Description
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 the new (paused) state.
Run Instructs the filter to transition to the new (running) state.
SetSyncSource Informs the filter of the reference clock it should synchronize activity with.
Stop Instructs the filter to transition to the new (stopped) state.

Implemented INonDelegatingUnknown Methods

Method Description
NonDelegatingQueryInterface Passes out references to interfaces supported by CBaseFilter.

To pass out pointers to interfaces supported in a derived filter class, override this.

Requirements

DirectShow applications and DirectShow filters have different include file and link library requirements.

For more information, see Setting Up the Build Environment.

OS Versions: Windows CE 2.12 and later. Version 2.12 requires DXPAK 1.0 or later.
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