Somebody wants Jack MIDI support in VMPK (again) ...

[pedrolcl]

You may exchange VMPK for Drumstick Multiplatform MIDI File Player or some other drumstick-rt based program.

The thing is: any program using Drumstick::RT MIDI input/output is using a backend that is built as a Qt plugin. There are some in-tree backend plugins, but nothing forbids to implement and distribute other out-of-tree plugins, implementing either Jack MIDI or anything else.

The other thing that I don't want is more modules inside the Drumstick repository. It is already big enough. What I want is to make it thinner, as for instance removing the sonivox library sources. Please don't ask for a merge request adding more modules to Drumstick.

Well, then. How to start? First, go to the drumstick-rt-outoftree project page, and press the "Use this template" big green button to generate a new repository based on the template. Now clone locally the new repository and start hacking!

If you want to create only a MIDI IN plugin, then remove the "dummyouyput" class. If you want a MIDI OUT plugin, then remove the "dummyinput" class. Rename the Dummy classes, and write your implementation. The minimal required functionality for the MIDI IN plugin (extending the drumstick::rt::MIDIInput class) is to emit the signals corresponding to each MIDI event type:

drumstick/library/include/drumstick/rtmidiinput.h

Lines 120 to 190 in 93a41f2

	Q_SIGNALS:
	/**
	* @brief midiNoteOff 0x8
	* @param chan
	* @param note
	* @param vel
	*/
	void midiNoteOff(const int chan, const int note, const int vel);
	/**
	* @brief midiNoteOn 0x9
	* @param chan
	* @param note
	* @param vel
	*/
	void midiNoteOn(const int chan, const int note, const int vel);
	/**
	* @brief midiKeyPressure 0xA
	* @param chan
	* @param note
	* @param value
	*/
	void midiKeyPressure(const int chan, const int note, const int value);
	/**
	* @brief midiController 0xB
	* @param chan
	* @param control
	* @param value
	*/
	void midiController(const int chan, const int control, const int value);
	/**
	* @brief midiProgram 0xC
	* @param chan
	* @param program
	*/
	void midiProgram(const int chan, const int program);
	/**
	* @brief midiChannelPressure 0xD
	* @param chan
	* @param value
	*/
	void midiChannelPressure(const int chan, const int value);
	/**
	* @brief midiPitchBend 0xE
	* @param chan
	* @param value
	*/
	void midiPitchBend(const int chan, const int value);
	/**
	* @brief midiSysex
	* @param data 0xF0 ... 0xF7
	*/
	void midiSysex(const QByteArray &data);
	/**
	* @brief midiSystemCommon
	* @param status 0xF (1..6)
	*/
	void midiSystemCommon(const int status);
	/**
	* @brief midiSystemRealtime
	* @param status 0xF (8..F)
	*/
	void midiSystemRealtime(const int status);

In the MIDI OUT plugin (extending the drumstick::rt::MIDIOutput class), you need to implement the public slots:

drumstick/library/include/drumstick/rtmidioutput.h

Lines 171 to 235 in 93a41f2

	public Q_SLOTS:
	/**
	* @brief sendNoteOff 0x8
	* @param chan
	* @param note
	* @param vel
	*/
	virtual void sendNoteOff(int chan, int note, int vel) = 0;
	/**
	* @brief sendNoteOn 0x9
	* @param chan
	* @param note
	* @param vel
	*/
	virtual void sendNoteOn(int chan, int note, int vel) = 0;
	/**
	* @brief sendKeyPressure 0xA
	* @param chan
	* @param note
	* @param value
	*/
	virtual void sendKeyPressure(int chan, int note, int value) = 0;
	/**
	* @brief sendController 0xB
	* @param chan
	* @param control
	* @param value
	*/
	virtual void sendController(int chan, int control, int value) = 0;
	/**
	* @brief sendProgram 0xC
	* @param chan
	* @param program
	*/
	virtual void sendProgram(int chan, int program) = 0;
	/**
	* @brief sendChannelPressure 0xD
	* @param chan
	* @param value
	*/
	virtual void sendChannelPressure(int chan, int value) = 0;
	/**
	* @brief sendPitchBend 0xE
	* @param chan
	* @param value
	*/
	virtual void sendPitchBend(int chan, int value) = 0;
	/**
	* @brief sendSysex
	* @param data 0xF0 ... 0xF7
	*/
	virtual void sendSysex(const QByteArray& data) = 0;
	/**
	* @brief sendSystemMsg
	* @param status 0xF
	*/
	virtual void sendSystemMsg(const int status) = 0;

You may implement backends for anything related to MIDI. For instance, MIDI synthesizers. By definition, a MIDI synthesizer is something that accepts MIDI events and produces audio output. This should be implemented as a MIDI OUT plugin: The MIDI events are provided by Drumstick::RT, and you need to provide some kind of audio output. You may find an example in the Drumstick::RT Out-of-Tree FluidLite Plugin. Other crazy ideas for Drumstick::RT plugins...

Output:

• VST3 Plugin, providing some kind of meta-plugin for VST3i synthesizers.
• LV2 Meta-plugin. Like the above, but for LV2 synthesizers.

Input:

• Linux input subsystem, providing MIDI events from Linux raw keyboard events (or other input events).

Both Input and Output:

• rtpMIDI network MIDI I/O, alternative to the existing ipMIDI backend.

Happy hacking!

[pedrolcl]

By the way, see also #7 about including configuration dialogs in the plugins