[Audacity-nyquist] new compressor feature

[Chris C. <pd...@gm...>]

I have added a couple new features to my compressor. They apply some
EQ to the incoming signal and then compress the EQ'd version. Because
of the EQ bands chosen, the sound has a perceptually more even volume,
but a numerically less even amplitude. The EQ bands compensate for the
regions where human hearing is much more sensitive and less sensitive.
(Actually, they exaggerate the signal, not compensate, so the
compressor "hears" what a human would.)

I actually have two different options for high and low, because
adjusting for the high sounds lowers the overall amplitude of the
output, which means no possibility of clipping. Compensating for the
low sounds means you have to manually lower the amplitude of the
incoming signal to avoid clipping, and by an amount that's different
for each input. To fix this, Audacity would have to be smarter about
how it handles data returned from plugins.

Currently I have (eq-band sound 4250 Hz 20 dB 1.25 octaves) for bright
sounds and (eq-band sound 50 -20 3) for bass sounds. It might be more
accurate with more bands, better tuned, but since different people's
hearing is different, tuning it too much is pointless, and anyway you
probably run into some serious diminishing returns after the first or
second band. However, suggestions are welcome.

Please give it a try and tell me what you think. I'll probably release
it pretty soon here.

Chris Capel
-- 
"What is it like to be a bat? What is it like to bat a bee? What is it
like to be a bee being batted? What is it like to be a batted bee?"
-- The Mind's I (Hofstadter, Dennet)