midiInOpen

Syntax

WORD midiInOpen(lphMidiIn, wDeviceID, dwCallback, dwCallbackInstance, dwFlags)

This function opens a specified MIDI input device.

Parameters

LPHMIDIIN lphMidiIn

Specifies a far pointer to an HMIDIIN handle. This location is filled with a handle identifying the opened MIDI input device. Use the handle to identify the device when calling other MIDI input functions.

WORD wDeviceID

Identifies the MIDI input device to be opened.

DWORD dwCallback

Specifies the address of a fixed callback function or a handle to a window called with information about incoming MIDI messages.

DWORD dwCallbackInstance

Specifies user instance data passed to the callback function. This parameter is not used with window callbacks.

DWORD dwFlags

Specifies a callback flag for opening the device.

CALLBACK_WINDOW

If this flag is specified, dwCallback is assumed to be a window handle.

CALLBACK_FUNCTION

If this flag is specified, dwCallback is assumed to be a callback procedure address.

Return Value

Returns zero if the function was successful. Otherwise, it returns an error number. Possible error returns are:

MMSYSERR_BADDEVICEID

Specified device ID is out of range.

MMSYSERR_ALLOCATED

Specified resource is already allocated.

MMSYSERR_NOMEM

Unable to allocate or lock memory.

Comments

Use midiInGetNumDevs to determine the number of MIDI input devices present in the system. The device ID specified by wDeviceID varies from zero to one less than the number of devices present.

If a window is chosen to receive callback information, the following messages are sent to the window procedure function to indicate the progress of MIDI input:

MM_MIM_OPEN

MM_MIM_CLOSE

MM_MIM_DATA

MM_MIM_LONGDATA

MM_MIM_ERROR

MM_MIM_LONGERROR

If a function is chosen to receive callback information, the following messages are sent to the function to indicate the progress of MIDI input:

MIM_OPEN, MIM_CLOSE

MIM_DATA

MIM_LONGDATA

MIM_ERROR

MIM_LONGERROR

The callback function must reside in a DLL. You do not have to use MakeProcInstance to get a procedure-instance address for the callback function.

Callback

void FAR PASCAL MidiInFunc(hMidiIn, wMsg, dwInstance, dwParam1, dwParam2)

MidiInFunc is a placeholder for the application-supplied function name. The actual name must be exported by including it in an EXPORTS statement in the DLL's module definition file.

Parameters

HMIDIIN hMidiIn

Specifies a handle to the MIDI input device.

WORD wMsg

Specifies a MIDI input message.

DWORD dwInstance

Specifies the instance data supplied with midiInOpen.

DWORD dwParam1

Specifies a parameter for the message.

DWORD dwParam2

Specifies a parameter for the message.

Comments

Because the callback is accessed at interrupt time, it must reside in a DLL, and its code segment must be specified as FIXED in the module-definition file for the DLL. Any data that the callback accesses must be in a FIXED data segment as well. The callback may not make any system calls except for PostMessage, timeGetSystemTime, timeGetTime, timeSetEvent, timeKillEvent, midiOutShortMsg, midiOutLongMsg, and OutputDebugStr.

See Also

midiInClose