IMDSPDeviceControl::Seek

The Seek method seeks to a position that is used as the starting point by the Play or Record methods.

Syntax

HRESULT Seek(
  UINT  fuMode,
  int  nOffset
);

Parameters

fuMode

[in] Mode for the seek operation being performed. The fuMode parameter must be one of the following modes.

Mode	Description
WMDM_SEEK_BEGIN	Seek to a position that is nOffset units after the beginning of the file.
WMDM_SEEK_CURRENT	Seek to a position that is nOffset units from the current position.
WMDM_SEEK_END	Seek to a position that is nOffset units before the end of the file.

nOffset

[in] Number of units of offset by which the seek operation moves the starting position away from the origin specified by fuMode. The units of nOffset are defined by the content. They can be milliseconds for music, pages for electronic books, and so on.

A positive value for nOffset indicates seeking forward through the file. A negative value indicates seeking backward through the file. Any combination of nOffset and fuMode that indicates seeking to a position before the beginning of the file or after the end of the file is invalid, and causes the method to return E_INVALIDARG.

Return Values

If the method succeeds, it returns S_OK. If it fails, it returns an HRESULT error code.

Return code	Description
E_INVALIDARG	One or more parameters are invalid.
WMDM_E_NOTSUPPORTED	Seek is not implemented on this device.
E_FAIL	An unspecified error occurred.

Remarks

The seek position is defined by passing either an IWMDMStorage interface pointing to a location on a storage medium of the device, or an IWMDMOperation interface that has been implemented to support streaming audio. The IMDSPObjectInfo interface can also be passed to describe some point within the object to which the specified interface points.

For device playback, if Seek is not called before Play, then playback starts at the first audio track on the first storage medium on the media device.

For device recording, if Seek is not called before Record, the record operation fails. Once the Record method is called, subsequent calls to the IMDSPObjectInfo::GetPlayPosition method report the total play length at any time, and equal the value returned from IMDSPObjectInfo::GetTotalLength. The recording length can be limited by calling the IMDSPObjectInfo::SetPlayLength method after returning from the Seek call.

See Also

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