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CSourceSeeking Class

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Windows Embedded CE 6.0 R3

4/8/2010

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This is an abstract class that assists source filters with the implementation of IMediaSeeking interface methods. This class enables a source filter to handle calls that change the start and stop positions in the media stream and the playback rate.

Derive from this class and set the positions.

This class supports IMediaSeeking, and calls the pure virtual member functions CSourceSeeking::ChangeStart, CSourceSeeking::ChangeStop, and CSourceSeeking::ChangeRate when CSourceSeeking::SetPositions or CSourceSeeking::SetRate is called, to enable a source filter to handle these commands and start sending new data.

Override the CSourceSeeking::ChangeStart, CSourceSeeking::ChangeStop, and CSourceSeeking::ChangeRate member functions to do something when the properties change.

Protected Data Members

Member Description

m_dRateSeeking

Playback rate. Set to 1 by default.

m_dwSeekingCaps

Seeking capabilities returned in the GetCapabilities function.

Can be one or more of the following values:

  • AM_SEEKING_CanSeekForwards
  • AM_SEEKING_CanSeekBackwards
  • AM_SEEKING_CanSeekAbsolute
  • AM_SEEKING_CanGetStopPos
  • AM_SEEKING_CanGetDuration.

Set to all of these by default.

m_pLock

Pointer to a CCritSec object for locking.

m_rtDuration

Duration of the stream. Set to m_rtStop by default.

m_rtStart

Start time.

Set to zero by default.

m_rtStop

Stop time.

Set to the largest positive 64-bit integer possible (9223372036854775807) by default.

Member Functions

Member function Description

CSourceSeeking

Constructs a CSourceSeeking object.

Overrideable Member Functions

Member function Description

ChangeRate

Override this pure virtual to handle notification of a change of sample rate.

ChangeStart

Override this pure virtual to handle notification of a change of start time.

ChangeStop

Override this pure virtual to handle notification of a change in stop time.

Implemented IMediaSeeking Methods

Method Description

CheckCapabilities

Checks that all requested capabilities are in m_dwSeekingCaps.

ConvertTimeFormat

Checks that the time format is TIME_FORMAT_MEDIA_TIME. This is the only format currently available.

GetAvailable

Retrieves the range of seeking times. Earliest is zero and latest is the media stream's duration.

GetCapabilities

Retrieves the current seeking capabilities in m_dwSeekingCaps.

GetCurrentPosition

Not currently implemented.

GetDuration

Retrieves the length of time the media stream will play.

GetPositions

Retrieves the current start and stop position settings.

GetPreroll

Sets the preroll time to zero.

GetRate

Retrieves the current playback rate.

GetStopPosition

Retrieves the position within the media stream at which playback should stop.

GetTimeFormat

Sets the time format to TIME_FORMAT_MEDIA_TIME. This is the only format currently supported.

IsFormatSupported

Determines if the requested format is TIME_FORMAT_MEDIA_TIME. This is the only format currently supported.

IsUsingTimeFormat

Determines if the requested format is TIME_FORMAT_MEDIA_TIME. This is the only format supported.

QueryPreferredFormat

Sets the preferred time format to TIME_FORMAT_MEDIA_TIME. This is the only format supported.

SetPositions

Sets current and stop positions, first checking that the seeking options are valid.

SetRate

Sets the playback rate.

SetTimeFormat

Checks that the time format is TIME_FORMAT_MEDIA_TIME. This is the only format supported.

Implemented INonDelegatingUnknown Methods

Method Description

NonDelegatingQueryInterface

Retrieves an interface and increments the reference count on the interface.

Requirements

Windows Embedded CE Windows CE 2.12 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