This message is used to set periodic position-change messages from the media device. The ulUnits field of the MCI_POSITION_PARMS data structure contains the interval that these messages are to be generated. The interval is relative to position 0 of the media. The ulUnits field is in the current time format, but the position-change messages are returned in MMTIME format.

ulParam1 (ULONG)

This parameter can contain any of the following flags:

MCI_NOTIFY

A notification message will be posted to the window specified in the hwndCallback parameter of the data structure pointed to by the pParam2 parameter. The notification will be posted when the action indicated by this message is completed or when an error occurs.
MCI_WAIT
Control is not to be returned until the action indicated by this message is completed or an error occurs.
MCI_SET_POSITION_ADVISE_ON
This flag specifies that position-change advise message frequency is to be set to the value specified in the ulUnits field of the MCI_POSITION_PARMS data structure.
MCI_SET_POSITION_ADVISE_OFF
This flag disables position-change advise messages.

pParam2 (PMCI_POSITION_PARMS)

A pointer to the MCI_POSITION_PARMS data structure.

rc (ULONG)

Return codes indicating success or type of failure:

MCIERR_SUCCESS

If the function succeeds, 0 is returned.
MCIERR_INVALID_DEVICE_ID
The device ID is not valid.
MCIERR_INSTANCE_INACTIVE
The device ID is currently inactive. Issue MCI_ACQUIREDEVICE to make device ID active.
MCIERR_MISSING_FLAG
A required flag is missing.
MCIERR_INVALID_FLAG
Given flag is invalid.
MCIERR_UNSUPPORTED_FLAG
Given flag is unsupported for this device.
MCIERR_INVALID_CALLBACK_HANDLE
Given callback handle is invalid.
MCIERR_FILE_NOT_FOUND
File has not been loaded.
MCIERR_OUT_OF_MEMORY
Out of memory.
MCIERR_OUTOFRANGE
Unit is out of range.
MCIERR_MISSING_PARAMETER
Required parameter is missing.

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