LeStahL / QMidi

Qt library for MIDI output & MIDI file I/O.

QMidi

A simple, cross-platform way to support MIDI in Qt. MIDI Output and MIDI File I/O is supported. MIDI output is supported on Windows (Windows Multimedia), Linux (ALSA), Haiku (Midi Kit 2), and macOS (CoreMIDI).

MIDI Output

The QMidiOut class provides an interface to the system's MIDI Out.

/* devices() returns a QMap where the key is the ID and
 * the value is the user-friendly name. */
QMap<QString, QString> vals = QMidiOut::devices();
QMidiOut midi;
midi.connect(/* one of the keys (IDs) from `devices()` */);

There's an easy API for sending messages:

midi.setInstrument(/* voice */ 0, /* instrument */ 0);
midi.noteOn(/* note */ 60, /* voice */ 0 /* , velocity */);
midi.noteOff(/* note */ 60, /* voice */ 0);

Alternatively, you could just send raw MIDI messages:

midi.sendMsg(0x90 + 0 | 60 << 8 | 64 << 16);
/* note on, voice 0; middle C (60); velocity 64 */

Or you could construct a QMidiEvent (from QMidiFile.h) and send it:

QMidiEvent e;
e.setType(QMidiEvent::NoteOn);
e.setVoice(0);
e.setNote(60);
e.setVelocity(64);
midi.sendEvent(e);

Once you're done:

midi.disconnect();

MIDI File I/O

Classes for MIDI file I/O were rewritten from Div's Midi Utilities (homepage | Google Code) from C to Qt/C++.

Quick example:

QMidiFile f;
f.load(" .. some filename .. ");
f.save(" .. some filename .. ");

You can get the events using f.events() which returns a QList<QMidiEvent*>*. For information on using these classes in conjuction with the MIDI output class to play files see the qtplaysmf example in the examples folder.

Python Bindings

Python bindings are available for the QMidi classes.