private static void playMidi(Sequence seq, float tempo, Set<Player> listeners)
throws InvalidMidiDataException, IOException, MidiUnavailableException
{
Sequencer sequencer = MidiSystem.getSequencer(false);
sequencer.setSequence(seq);
sequencer.open();
// slow it down just a bit
sequencer.setTempoFactor(tempo);
NoteBlockReceiver noteblockRecv = new NoteBlockReceiver(listeners);