
The spin filter temporarily causes a section
of music to be looped.  While this loop is 
being played back, the underlying song 
continues to play at a normal speed, so that
it will stay synchronized.

The major parameter is the amount of delay.  This
is displayed as a number of whole beats.  If the
bpm of the song is not known, a tempo of 60 bpm
is assumed.  If a negative number is specified
as the beat factor, then the delay will be the
negative inverse of that number; for instance,
a value of -2 corresponds to a half beat period.

The spin filter can be locked into a spin mode.
In this situation, depressing the temporary
spin button will cause the looped buffer to be
overwritten by whatever the underlying song is 
playing.  The spun sound will die if the
underlying song stops.

