MIDIOPENDESC

See also MIDIOPENSTRMID, MODM_OPEN, MIDM_OPEN

typedef struct midiopendesc_tag {
    HMIDI          hMidi;
    DWORD          dwCallback;
    DWORD          dwInstance;
    WORD           uReserved;    // reserved; do not use
    DWORD          dnDevNode;
    DWORD          cIds;
    MIDIOPENSTRMID rgIds;
} MIDIOPENDESC;

Contains information needed by a MIDI input or MIDI output device driver when devices are opened with a MODM_OPEN or MIDM_OPEN message.

hMidi

Specifies the client's handle to the device, assigned by MMSYSTEM. Use this handle when notifying the client with the DriverCallback function.

dwCallback

Specifies either the address of a callback function, a window handle, or a task handle, depending on the flags specified in the dwParam2 parameter of the MODM_OPEN or MIDM_OPEN message. If this field contains a handle it is contained in the low-order word. The driver uses this information to notify the client using the DriverCallback function.

dwInstance

Specifies a DWORD of instance information for the client. This instance information is returned to the client whenever the driver notifies the client using the DriverCallback function.

dnDevNode

Specifies a device node for the device (if the device is Plug and Play).

cIds

Specifies the number of stream identifiers, if a stream is open.

rgIds

Specifies an array of device identifiers. The number of identifiers is given by the cIds member.