A fork of ZMusic, GZDoom's MIDI music system as a standalone library.
Compile instructions are pretty simple for most systems.
git clone https://github.com/jerome-trc/zmsx.git
mkdir zmsx/build
cd zmsx/build
cmake -DCMAKE_BUILD_TYPE=Release ..
cmake --build .
On Unix/Linux you may also supply sudo make install in the build folder to push the compiled library directly into the file system so that it can be found by the previously mentioned projects.