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CSourceSeekingis an abstract class that assists source filters with the implementation of IMediaSeekinginterface 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::ChangeRatewhen CSourceSeeking::SetPositionsor CSourceSeeking::SetRateis called, to enable a source filter to handle these commands and start sending new data.
Override the CSourceSeeking::ChangeStart, CSourceSeeking::ChangeStop, and CSourceSeeking::ChangeRatemember functions to do something when the properties change.
Protected Data Members
| m_dRateSeeking | Playback rate. Set to 1 by default. |
| m_dwSeekingCaps | Seeking capabilities returned in the GetCapabilitiesfunction. 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 CCritSecobject for locking. |
| m_rtDuration | Duration of the stream. Set to m_rtStopby 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
| CSourceSeeking | Constructs a CSourceSeekingobject. |
Overridable Member Functions
| 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
| 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 currently supported. |
| QueryPreferredFormat | Sets the preferred time format to TIME_FORMAT_MEDIA_TIME. This is the only format currently 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 currently supported. |
Implemented INonDelegatingUnknown Methods
| NonDelegatingQueryInterface | Retrieves an interface and increments the reference count on the interface. |