A given track always retains its
recorded MIDI channel information, so that if a track contains notes from more than one channel, it can
be played back as recorded. In this case, it is desired to assign the track to UNCHANGED, which means
that it will output on the same MIDI channels as are recorded. Whenever a new track is recorded, it
defaults to UNCHANGED. If a specific MIDI channel is selected (1-16). then the selected track's notes will
all be output on the selected channel. However, the actual track information remains unchanged, so that
returning a track to UNCHANGED will cause the separate MIDI channels to play back as before.