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IWMSPacketStreamer::Seek
The Seek method seeks to a specific offset in a digital media stream.
Syntax
HRESULT Seek( );
Parameters
pCommand
[in] Pointer to an IWMSCommandContext interface containing the associated context.
dwOffsetType
[in] Member of the WMS_SEEK_TYPE enumeration type. This must be one of the following values.
| Value | Description |
| WMS_SEEK_TO_BYTE_OFFSET | Indicates that the offset value is specified in bytes. |
| WMS_SEEK_TO_PACKET | Indicates that the offset value is specified by a packet number. |
| WMS_SEEK_TO_PLAYLIST_ENTRY | Indicates that the offset value is specified by an index into a playlist. |
| WMS_SEEK_TO_TIME | Indicates that the offset value is specified in milliseconds. |
qwOffset
[in] QWORD containing the offset value.
dwFlags
[in] Reserved for future use.
pCallback
[in] Pointer to an IWMSPacketStreamerCallback interface used to report the status of the method call.
qwContext
[in] QWORD containing a value defined by the server to identify which call to Seek the plug-in is responding to when it calls IWMSPacketStreamerCallback::OnSeek. You must pass this value back unaltered.
Return Values
If the method succeeds, the plug-in must return S_OK. To report an error, the plug-in can return any HRESULT other than S_OK. If the plug-in uses the IWMSEventLog interface to log error information directly to the Windows Event Viewer, it is recommended that it return NS_E_PLUGIN_ERROR_REPORTED. Typically, the server attempts to make plug-in error information available to the server object model, the Windows Event Viewer, and the troubleshooting list in the details pane of the Windows Media Services MMC. However, if the plug-in uses the IWMSEventLog interface to send custom error information to the Windows Event Viewer, returning NS_E_PLUGIN_ERROR_REPORTED stops the server from also logging to the event viewer. For more information about retrieving plug-in error information, see Identifying Plug-in Errors.
Remarks
If this method returns S_OK, and if it does not call Seek on an upstream module in which it passes in the original arguments, the IWMSPacketStreamerCallback::OnSeek method must be called.
The Seek method returns the minimum seek point of all selected streams. When a media parser seeks to a point, it must return all frames after and including the first key frame of the stream. This enables you to ignore partial frames that are after the common seek point but before the next key frame.
Example Code
Requirements
Header: wmsdatapath.h.
Library: WMSServerTypeLib.dll.
Platform: Windows Server 2003, Enterprise Edition; Windows Server 2003, Datacenter Edition; Windows Server 2008.
See Also
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