I can't seem to figure it out. When it plays a MIDI file, it references Timidity++ in the output:

  Metadata:
    name            : Piano
    instrument      : Timidity GM patches
    sample          : Piano
                    : 0:
                    : 1:
                    : 2:
                    : 3:
                    : 4:
                    : 5:
                    : 6:
                    : 7:
                    : 8:
                    : 9:
                    : 10:
    extra info      : 51 patterns, 26 channels, 1/11 instrument, 12/12 samples
  Duration: 00:03:06.00, bitrate: 1 kb/s
  Stream #0:0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s

Playing the file with Timidity++ results in nothing, as Timidity++ apparently isn't a soundfont, and searching "Timidity GM patches" brings up nothing.