CBaseReferenceClock::AdvisePeriodic

Sets up a recurring advise with the reference clock.

HRESULT AdvisePeriodic(
  REFERENCE_TIME StartTime,
  REFERENCE_TIME PeriodTime,
  HSEMAPHORE hSemaphore,
  DWORD* pdwAdviseToken
);

Parameters

• StartTime
  Start at this time.
• PeriodTime
  Time between notifications.
• hSemaphore
  Advise through a semaphore.
• pdwAdviseToken
  Advise token that identifies the link with the clock.

Return Values

Returns one of the following HRESULT values.

Remarks

A semaphore is used, rather than an event, to ensure that multiple notifications can be seen by the user. Each time an amount of time specified in the PeriodTime parameter elapses, the semaphore will be released.

When no further notifications are required, call CBaseReferenceClock::Unadvise and pass the pdwAdviseToken value returned from this call.

For example, the following code extract sets up an advise link that fires its first advise five seconds from now and then signals every second until Unadvise is called. By using a semaphore with a count of 10, the clock is effectively able to cache 10 events.

HANDLE hSemaphore = CreateSemaphore(NULL, 0, 10, NULL);
    // Assume pRefClock is an IReferenceClock* variable.

    REFERENCE_TIME rtPeriodTime = 1000 * (UNITS / MILLISECONDS);
        // A one-second interval
    REFERENCE_TIME rtNow;
    DWORD    dwAdviseToken;
    pRefClock->GetTime(&rtNow);

    pRefClock->AdvisePeriodic(rtNow+(5*rtPeriodTime),
        PeriodTime, hSemaphore, &dwAdviseToken);

Requirements

DirectShow applications and DirectShow filters have different include file and link library requirements. See Setting Up the Build Environment for more information.

OS Versions: Windows CE 2.12 and later. Version 2.12 requires DXPAK 1.0 or later.
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Last updated on Wednesday, April 13, 2005

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