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								| midiOutOpen The midiOutOpen function opens a MIDI output device for playback. | VB4-32,5,6 Declare Function midiOutOpen Lib "winmm.dll" (lphMidiOut As Long, ByVal uDeviceID As Long, ByVal dwCallback As Long, ByVal dwInstance As Long, ByVal dwFlags As Long) As Long
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 | Operating Systems Supported | 
 | Requires Windows NT 3.1 or later; Requires Windows 95 or later | 
 
 | · lphmo Address of an HMIDIOUT handle. This location is filled with a handle identifying the opened MIDI output device. The handle is used to identify the device in calls to other MIDI output functions.
 
 · uDeviceID
 Identifier of the MIDI output device that is to be opened.
 
 · dwCallback
 Address of a callback function, an event handle, a thread identifier, or a handle of a window or thread called during MIDI playback to process messages related to the progress of the playback. If no callback is desired, specify NULL for this parameter. For more information on the callback function, see MidiOutProc.
 
 · dwCallbackInstance
 User instance data passed to the callback. This parameter is not used with window callbacks or threads.
 
 · dwFlags
 Callback flag for opening the device. It can be the following values:
 CALLBACK_EVENT
 The dwCallback parameter is an event handle. This callback mechanism is for output only.
 CALLBACK_FUNCTION
 The dwCallback parameter is a callback function address.
 CALLBACK_NULL
 There is no callback mechanism. This value is the default setting.
 CALLBACK_THREAD
 The dwCallback parameter is a thread identifier.
 CALLBACK_WINDOW
 The dwCallback parameter is a window handle.
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 | Returns MMSYSERR_NOERROR if successful or an error otherwise. Possible error values include the following: MIDIERR_NODEVICE
 No MIDI port was found. This error occurs only when the mapper is opened.
 
 MMSYSERR_ALLOCATED
 The specified resource is already allocated.
 
 MMSYSERR_BADDEVICEID
 The specified device identifier is out of range.
 
 MMSYSERR_INVALPARAM
 The specified pointer or structure is invalid.
 
 MMSYSERR_NOMEM
 The system is unable to allocate or lock memory.
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