This repository is no longer maintained and I don't intend to work on it anymore. It's old code, may be buggy and these days I don't program C# so much anymore.
I have a similar library for C++ with much cleaner code and probably less bugs called cppmidi. So if you're familiar with C++, you should definitely check it out.
"csmidi" is a library which I've used a couple of times for basic midi processing functions. It's intended to not have a bulk of features to ease using it.