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DirectShow provides two classes, CBaseReferenceClockand CSystemClockto help implement clocks in the filter graph. The following illustration shows the relationship between these classes and the interfaces they implement.
CBaseReferenceClockimplements IReferenceClock, and so provides the ability to return the correct reference time when requested, and to advise registered objects of specific times or time intervals through event notification and semaphores.
CSystemClockimplements a system clock that provides time information and timing signals to an application. It uses the CBaseReferenceClockbase class to provide most of that functionality, overriding the actual time calls.
Last updated on Tuesday, May 18, 2004