ulParam1 (ULONG)

      This parameter can contain any of the following flags. MCI_OPEN_ELEMENT and MCI_OPEN_MMIO are mutually exclusive 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_DOS_QUEUE
        This flag specifies that window handles passed in for this device instance will be treated as OS/2 Control Program queue handles.
      MCI_OPEN_ALIAS
        This flag specifies that the pszAlias field of the open structure contains an alias for this device instance. This alias can then be used on subsequent commands using the string interface.
      MCI_OPEN_ELEMENT
        This flag specifies that an element name is included. The element name can be that of a file or a file element in a compound file. The element name is specified in the pszElementName field of the open data structure. If the element name does not exist or is NULL, then a temporary element is created for subsequent use. The temporary file can be made permanent by providing a name using the MCI_SAVE message.
      MCI_OPEN_MMIO
        This flag specifies that an MMIO handle (hmmio) is passed in the pszElementName field of the open data structure. The file must have been opened through MMIO with ulTranslate of the MMIOINFO data structure set to MMIO_TRANSLATEHEADER, unless a particular MCD indicates differently.
      MCI_OPEN_PLAYLIST
        This flag indicates that the pszElementName field of the open data structure contains a pointer to a memory playlist structure.
      MCI_OPEN_READONLY
        This flag specifies that the file is to be opened in read-only mode. The load and run-time performance for the wave audio and digital video devices can be improved by specifying this flag. This flag can only be used in conjunction with the MCI_OPEN_ELEMENT or MCI_OPEN_MMIO flags. By specifying this flag, MCI_RECORD and MCI_SAVE are automatically disabled.
      MCI_OPEN_SHAREABLE
        This flag specifies that the device instance is to be opened in a fully shareable mode. Omitting this flag causes the device instance to be opened for exclusive use.
      MCI_OPEN_TYPE_ID
        This flag specifies that the pszDeviceType field of the open data structure is to be interpreted as follows. The low-order word is a standard device type and the high-order word is the ordinal index for the device. If MCI_OPEN_TYPE_ID is specified and the index is 0, the default device will be opened. If MCI_OPEN_TYPE_ID is not specified and the pszDeviceType field is not NULL, the media control interface will attempt to open the device specified by pszDeviceType. If MCI_OPEN_TYPE_ID is not specified, pszDeviceType is NULL, and the MCI_OPEN_ELEMENT flag is specified, the system attempts to select and open a device based on the element extension or EA type of the file specified in the pszElementName field of the open data structure.
      Digital Video Extensions

      The following flags apply to digital video devices:

      MCI_DGV_OPEN_PARENT

        This flag indicates that the hwndParent field of the open data structure contains a valid parent window handle. If this flag is not specified, HWND_DESKTOP is assumed to be the parent window handle.
      Video Overlay Extensions

      The following flag applies to video overlay devices:

      MCI_OVLY_OPEN_PARENT

        This flag indicates that the hwndParent field of the open data structure contains a valid parent window handle. If this flag is not specified, HWND_DESKTOP is assumed to be the parent window handle.

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