This MCI command message releases access to a device or device element. All devices respond to this message. MMSYSTEM translates this message to the DRV_CLOSE and MCI_CLOSE_DRIVER messages sent to the device driver.
DWORD lParam1
The following flags apply to all devices:
MCI_NOTIFY
Specifies that MCI should post the MM_MCINOTIFY message when this command completes. The window to receive this message is specified in the dwCallback field of the data structure identified by lpDefault. Device drivers should send MM_MCINOTIFY just before returning from MCI_CLOSE_DRIVER.
MCI_WAIT
Specifies that the close operation should finish before MCI returns control to the application.
LPMCI_GENERIC_PARMS lParam2
Specifies a far pointer to the MCI_GENERIC_PARMS data structure. (Devices with extended command sets might replace this data structure with a device-specific data structure.)
Returns zero if successful. Otherwise, it returns an MCI error code.
Exiting an application without closing any MCI devices it has opened can leave the
device opened and unaccessible. Your application should explicitly close each device
or device element when it is finished with it. MCI unloads the device when all instances
of the device or all device elements are closed.