libremidi is a cross-platform C++17 library for real-time and MIDI file input and output.

This is a fork based on two libraries:

• RtMidi
• ModernMIDI

Instead of adding another abstraction layer like ModernMIDI does, this directly modernizes the RtMidi codebase with new C++ features and improvements:

• The library can be used header-only, as explained in the docs

• Callbacks are passed by std::function and generally simplified.

• Ability to use boost::small_vector to pass midi bytes instead of std::vector to reduce allocations.

• Allow to pass span when available (C++20) or (uint8_t* bytes, std::size_t size) pairs whenever possible to reduce copying.

• Less indirections, virtuals and memory allocations.

• Simplify usage of some functions, use C++ return style everywhere.

• Use of standard C++ snake_case.

• Simplification of exceptions.

• Passes clean through clang-tidy, clang analyzer, GCC -Wall -Wextra, ASAN, UBSAN etc etc.

• JACK support on Windows.
• JACK support through weakjack to allow runtime loading of JACK.
• UWP MIDI support on Windows
• Emscripten support to run on a web browser with WebMIDI.
• Raw ALSA support in addition to the existing ALSA sequencer support.

• Notification of device connection / disconnection.
• Support chunking of output data (only supported on raw ALSA backend so far).

• MIDI 2.0 support.
• More tests and compliance checks.
• Work even more towards this library being a zero-cost abstraction on top of native MIDI APIs.
• Rethink some design issues with the original RtMidi, for instance the way port numbers work is not reliable.
• Refactor duplicated code across backends.

• ossia.io: libremidi is used for every MIDI operation.