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Thursday, December 8, 2011

Virtual MIDI Piano Keyboard (VMPK) is a MIDI events generator and receiver.

Virtual MIDI Piano Keyboard is a MIDI events generator and receiver.

It doesn't produce any sound by itself, but can be used to drive a MIDI synthesizer (either hardware or software, internal or external).

You can use the computer's keyboard to play MIDI notes, and also the mouse.

You can use the Virtual MIDI Piano Keyboard to display the played MIDI notes from another instrument or MIDI file player.

To do so, connect the other MIDI port to the input port of VMPK.

VMPK 0.3.0

VMPK has been tested in Linux, but maybe you can build it also in other systems.

The Virtual Keyboard by Takashi Iway (vkeybd) has been the inspiration for this one. It is a wonderful piece of software and has served us well for many years.

VMPK uses a modern GUI framework: Qt4, that gives excellent features and performance. RtMIDI provides MIDI input/output features. Both frameworks are free and platform independent, available for Linux, Windows and Mac OSX.

The alphanumeric keyboard mapping can be configured from inside the program using the GUI interface, and the settings are stored in XML files. Some maps for Spanish, German and French keyboard layouts are provided, translated from the ones provided by VKeybd.

VMPK can send program changes and controllers to a MIDI synth. The definitions for different standards and devices can be provided as .INS files, the same format used by QTractor and TSE3. It was developed by Cakewalk and used also in Sonar.

This software is in a very early alpha stage. See the TODO file for a list of pending features. Please feel free to contact the author to ask questions, report bugs, and propose new features. You can use the tracking system at SourceForge project site.

Virtual MIDI Piano Keyboard is free software licensed under the terms of the GPL v3 license.


Getting started.

MIDI concepts.

MIDI is an industry standard to connect musical instruments. It is based on transmitting the actions performed by a musician playing some instrument to another different instrument.  Musical instruments enabled with MIDI interfaces typically have two DIN sockets labeled MIDI IN and MIDI OUT.

Sometimes there is a third socket labeled MIDI THRU.  To connect a MIDI instrument to another one, you need a MIDI cable attached to the MIDI OUT socket of the sending instrument, and to the MIDI IN of the receiving one. You can find more information and tutorials like this one all around the Net.

There are also hardware MIDI interfaces for computers, providing MIDI IN and OUT ports, where you can attach MIDI cables to communicate the computer with external MIDI instruments. Without needing hardware interfaces, the computer can also use MIDI software. An example is VMPK, which provides MIDI IN and OUT ports. You can attach virtual MIDI cables to the VMPK's ports, to connect the program to other programs or to the computer's physical MIDI interface ports.  More details about this coming later. You usually want to connect the MIDI output from VMPK to the input of some synthesizer which transforms MIDI into sound. Another common destination for the connection would be a MIDI monitor that translates MIDI events into readable text. This will help you to understand what kind of information is transmitted using the MIDI protocol. In Linux you can try KMidimon and in Windows MIDIOX.

VMPK doesn't produce any sound. You need a MIDI software synthesizer to hear the played notes. I recommend you to try QSynth, a graphical front-end to Fluidsynth. It is also possible to use the "Microsoft GS Wavetable SW Synth" that comes with XP. Of course, an external MIDI hardware synth would be an even better approach.


Keyboard maps and instrument definitions.

VMPK can help you to change sounds in your MIDI synthesizer, but only if you provide a definition for the synthesizer sounds first. The definitions are text files with the .INS extension, and the same format used by Qtractor (Linux).

When you start VMPK the first time, you should open the Preferences dialog and choose a definition file, and then select the instrument name among those provided by the definitions file. There should be one instrument definitions file installed in the VMPK's data directory (typically "/usr/share/vmpk" in Linux, and "C:\Program Files\VMPK" in Windows) named "gmgsxg.ins", containing definitions for the General MIDI, Roland GS and Yamaha XG standards. It is a very simple format, and you can use any text editor to look, change, and create a new one.

You can find a library of instruments definitions at the cakewalk ftp server.

Since the release 0.2.5 you can also import Sound Font files (in .SF2 or DLS formats) as instruments definitions, using a dialog available at menu File->Import SoundFont.
Another customization that you may want to tweak is the keyboard mapping. The default layout maps about two and half octaves for the QWERTY alphanumeric keyboard, but there are some more definitions in the data directory, adapted for other international layouts. You can even define your own mapping using a dialog box available in the Edit->Keyboard map menu. There are also options to load and save the maps as XML files.

The last loaded map will be remembered the next time you start VMPK. In fact, all your preferences, selected MIDI bank and program, and the controller values will be saved on exit, and restored when you restart VMPK the next time.

MIDI connections and virtual MIDI cables

To connect hardware MIDI devices you need physical MIDI cables. To connect MIDI software you need virtual cables. In Windows you can use some virtual MIDI cable software, like MIDI Yoke, Maple, LoopBe1 or Sony Virtual MIDI Router.

MIDI Yoke setup process will install the driver and a control panel applet to change the number of MIDI ports that will be available (you need to restart the computer after changing this setting). MIDI Yoke works sending every MIDI event written to an OUT port to the corresponding IN port. For instance, VMPK can connect the output to the port 1, and another program like QSynth can read the same events from the port 1.

Using MIDIOX you can add more routes between MIDI Yoke ports and other system MIDI ports. This program also provides other interesting functionalities, like a MIDI file player. You can listen the songs played in a MIDI Synth and at the same time see the played notes (only one channel at a time) in VMPK. To do so, you can use the "Routes" window in MIDIOX to connect the input port 1 to the Windows Synth port. Also, configure the player's MIDI port to send to MIDI Yoke 1. And configure VMPK Input port to read from MIDI Yoke 1. The player will send the events to the out port 1, which will be routed to both the input port 1 and at the same time to the synth port.

In Linux, you have ALSA sequencer to provide the virtual cables. The ports are dynamically created when you start a program, so there is not a fixed number of them like in MIDI Yoke. The command line utility "aconnect" allows to connect and disconnect the virtual MIDI cables between any ports, being hardware interfaces or applications.

A nice GUI utility for doing the same is QJackCtl. The main purpose of this program is to control the Jack daemon (start, stop and monitor the state). Jack provides virtual audio cables to connect your sound card ports and audio programs, in a similar way to the MIDI virtual cables, but for digital audio data.


qjackctl connections window

Screenshots.


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