For Yamaha users, this tool is a lifesaver. You can take the CSV output, manually add Meta Events (like embedded chord data), and use the "Convert CSV to MIDI" tool to rebuild a fully functional Yamaha XF file.
At its heart, GNMIDI is more than just a player; it is an all-in-one suite for MIDI optimization. Its capabilities are broadly categorized into playback, conversion, and surgical editing.