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CSourceSeeking.ChangeStart method

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[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The ChangeStart method is called when the start position changes.

Syntax

virtual HRESULT ChangeStart() = 0;

Parameters

This method has no parameters.

Return value

Returns an HRESULT value.

Remarks

The CSourceSeeking::SetPositions method calls this method if the start position changes. This method is pure virtual; the derived class must implement it. After a seek operation, time stamps should restart from zero. Media times should reflect the new start time. The following example shows a possible implementation:

HRESULT CMyStream::ChangeStart( )
{
    m_rtSampleTime = 0;          // Reset the time stamps.
    m_rtMediaTime = m_rtStart;   // Reset the media times.
    UpdateFromSeek();
    return S_OK;
}

Requirements

Requirement Value
Header
Ctlutil.h (include Streams.h)
Library
Strmbase.lib (retail builds);
Strmbasd.lib (debug builds)

See also

CSourceSeeking Class