COM objects > MidiDevices object > Methods > MidiDevices.InputEventCallbackSet method

Remarks

Sets or resets the callback function that will manage the notification that a MIDI event was received from the given MIDI input device.

For further details about input events management see the How to synchronize the container application with the control tutorial.

For further details about the use of MIDI devices see the MidiDevices object section and the How to manage MIDI devices tutorial.

Syntax

[Visual Basic]

control.MidiDevices.InputEventCallbackSet (

nDeviceUniqueId as Integer,

bRawEvent as enumBoolean,

pCallback as Long,

nUserdata as Long

) as enumDjcErrorCodes

[C++]

short control.MidiDevices.InputEventCallbackSet (

short nDeviceUniqueId,

const VARIANT FAR& bRawEvent,

long pCallback,

long nUserdata

);

Parameter

Description

nDeviceUniqueId

The unique identifier of the MIDI input device returned by a previous call to the MidiDevices.Open method

bRawEvent

Boolean value that specifies if the callback function is related to a short or raw MIDI event.

Supported values are the following:

Mnemonic constant	Value	Meaning
BOOL_FALSE	0	The callback function manages short MIDI events
BOOL_TRUE	1	The callback function manages raw MIDI events

pCallback

Pointer to the callback function containing the code that will manage the event. When the callback function is set, the control will not fire the MidiDevicesEventReceived event.

Set this value to 0 in order to reset the usage of the callback function and to manage again incoming events through the MidiDevicesEventReceived event.

A callback function for short MIDI events is defined like this:

[Visual Basic]

Public Sub MidiInputShortEventsCallback (

ByVal nDeviceUniqueId As Integer,

ByVal nMidiCommand As Integer,

ByVal nMidiChannel As Integer,

ByVal nMidiData1 As Integer,

ByVal nMidiData2 As Integer,

ByVal nTimeStamp As Long,

ByVal nUserData As Long

)

[Visual C++]

void CALLBACK MidiInputShortEventsCallback (

short nDeviceUniqueId,

short nMidiCommand,

short nMidiChannel,

short nMidiData1,

short nMidiData2,

long nTimeStamp,

long nUserData

);

where:

nDeviceUniqueId	The unique identifier of the MIDI input device which generated the event as returned by a previous call to the MidiDevices.Open method
nMidiCommand	Number representing the MIDI command
nMidiChannel	Number representing the MIDI channel
nMidiData1	Number representing the first parameter (Data1) related to the MIDI event
nMidiData2	Number representing the second parameter (Data2) related to the MIDI event
nTimeStamp	The time stamp of the event expressed in milliseconds elapsed from the moment in which the MIDI input device of the DJ Console was opened through a call to the MidiDevices.Open method.
nUserData	User instance data to pass to the callback function

A callback function for raw MIDI events is defined like this:

[Visual Basic]

Public Sub MidiInputRawEventsCallback (

ByVal nDeviceUniqueId As Integer,

ByVal pBuffer As Long,

ByVal nBufferLenght As Long,

ByVal nTimeStamp As Long,

ByVal nUserData As Long

)

[Visual C++]

void CALLBACK MidiInputRawEventsCallback (

short nDeviceUniqueId,

void *pBuffer,

long nBufferLenght,

long nTimeStamp,

long nUserData

);

where:

nDeviceUniqueId	The unique identifier of the MIDI input device which generated the event as returned by a previous call to the MidiDevices.Open method
nBufferLenght	Length of the buffer expressed in bytes
nTimeStamp	The time stamp of the event expressed in milliseconds elapsed from the moment in which the MIDI input device of the DJ Console was opened through a call to the MidiDevices.Open method.
nUserData	User instance data to pass to the callback function

nUserdata

User instance data to pass to the callback function

Return value

Value	Meaning

Negative value	An error occurred, check the LastError property value in order to get the error code
enumErrorCodes.ERR_NOERROR (0)	The method call was successful