RtMidi

A set of C++ classes that provide a common API for realtime MIDI input/output across Linux (ALSA & JACK), Macintosh OS X (CoreMIDI & JACK), Windows (Multimedia Library & UWP), Web MIDI, iOS and Android.

By Gary P. Scavone, 2003-2023.

This distribution of RtMidi contains the following:

• doc: RtMidi documentation (also online at https://caml.music.mcgill.ca/~gary/rtmidi/)
• tests: example RtMidi programs

On Unix systems, type ./configure in the top level directory, then make in the tests/ directory to compile the test programs. In Windows, open the Visual C++ workspace file located in the tests/ directory.

If you checked out the code from git, please run ./autogen.sh before ./configure.

Overview

RtMidi is a set of C++ classes (RtMidiIn, RtMidiOut, and API specific classes) that provide a common API (Application Programming Interface) for realtime MIDI input/output across Linux (ALSA, JACK), Macintosh OS X (CoreMIDI, JACK), and Windows (Multimedia Library) operating systems. RtMidi significantly simplifies the process of interacting with computer MIDI hardware and software. It was designed with the following goals:

• object oriented C++ design
• simple, common API across all supported platforms
• only one header and one source file for easy inclusion in programming projects
• MIDI device enumeration

MIDI input and output functionality are separated into two classes, RtMidiIn and RtMidiOut. Each class instance supports only a single MIDI connection. RtMidi does not provide timing functionality (i.e., output messages are sent immediately). Input messages are timestamped with delta times in seconds (via a double floating point type). MIDI data is passed to the user as raw bytes using an std::vector<unsigned char>.

RtMidi is also offered as a module, which is enabled with RTMIDI_BUILD_MODULES, and is accessed with import rt.midi;. Namespaces are implicitly imported (unless disabled with RTMIDI_USE_NAMESPACE), so classes can be accessed through namespace rt::midi or through the global namespace (for example, rt::midi::MidiApi and ::MidiApi are both valid).

Windows

In some cases, for example to use RtMidi with GS Synth, it may be necessary for your program to call CoInitializeEx and CoUninitialize on entry to and exit from the thread that uses RtMidi.

Further reading

For complete documentation on RtMidi, see the doc directory of the distribution or surf to https://caml.music.mcgill.ca/~gary/rtmidi/.

Legal and ethical

The RtMidi license is similar to the MIT License, with the added feature that modifications be sent to the developer. Please see LICENSE.