channel is used. Unfortunately,
some modules do not use these exact values. It is best to do a binary-
search (unless you use the period as the offset of an array of notes..
expensive), especially if you plan to use periods outside the "standard"
range. Periods are the internal representation of the pitch, so effects
that alter pitch (eg. sliding) alter the period value (see "effects"
below).

          C    C#   D    D#   E    F    F#   G    G#   A    A#   B
Octave 1: 856, 808, 762, 720, 678, 640, 604, 570