alternate waveform rendering at wave density
when zoomed out and waveform displays solids
(white-on-blue), allow for choosing colours and colour
gradients for the wave and not-wave regions, also for
tops of wave and below. See example attachment, using
4 gradient palettes. Alternatives, you could define
wave-colour gradient as relative to wave rather than
relative to 0db (sweep-style). Also define colour for
edge-tracing the waveform solid. This is eye candy,
though, definately not important.
Inspiration: pine trees reflecting in a lake at sunset
. . .