CSourceSeeking Class
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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:
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 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
| Method | Description |
|---|---|
| NonDelegatingQueryInterface | Retrieves an interface and increments the reference count on the interface. |
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
© 2005 Microsoft Corporation. All rights reserved.