Drumstick is a set C++ MIDI libraries using Qt5 objects, idioms and
style.  It contains a C++ wrapper around the ALSA library sequencer
interface; ALSA sequencer provides software support for MIDI technology
on Linux.

A complementary library provides classes for SMF (Standard MIDI files:
.MID/.KAR), and Cakewalk (.WRK) file formats processing. A multiplatform
realtime MIDI I/O library and GUI Widgets are also provided.

You also get in GUI: midi file player, drumgrid, virtual piano
And in CLI: metronome, dump{mid,ove,smf,wrk}, playsmf.