PortMidi

BaH.Portmidi is a BlitzMax implementation of Portmidi, a platform independent library for MIDI.

Using Portmidi

The Portmidi module is built around the use of callbacks.
The main type, TPortMidi is initialized with two of them. An error callback, and a read callback. You need to implement these functions to allow Portmidi to inform you when something happens.

The read function is called when MIDI Input data becomes available for a particular stream.

The error function is called when Portmidi determines that something has gone wrong.

A minimal example might look like :

Function err(errorNumber:Int, errorString:String)
	Print "Oops - " + errorString
	End
End Function

Function read(stream:TPortMidiStream, length:Int, messages:TMidiMessage[])
	Print length + " messages available"
End Function

Local midi:TPortMidi = TPortMidi.Create(err, read)

If midi Then

	midi.openInput(0)
	
	While Not KeyDown(key_escape)
		WaitEvent
	Wend

End If

A TMidiMessage represents a MIDI event sent by a MIDI device - for example, a keyboard key press.
The fields... status, data1 and data2, provide the message details.

A single read() event can have multiple message parts. You can use length to determine how many messages are available to process.
Do not use the length of the messages array as this may be larger than the number of actual available messages. (The array is static and grows when required, but isn't reset in an effort to keep it efficient).

SysEx

You can send and receive a SysEx message via the sendReceiveSysEx() method of TPortMidi. This method takes another callback function as a parameter, which will be called once the SysEx reply from the device is received. The receive part of this runs on the same background timer as the rest of the module, and so you can continue with your app while data is received from the device.

Local data:String = Chr($F0) + Chr($7E) + Chr($00) + Chr($06) + Chr($01) + Chr($F7)

midi.sendReceiveSysEx(1, 3, data, Null, sysexCallback)

' hang around and wait for the end...
While Not KeyDown(key_escape)
	WaitEvent
Wend

End

Function sysexCallback(recMessage:String, userData:Object)
	' .....
End Function

Constants

Types

Module Information