13 Feb
2010
13 Feb
'10
8:51 p.m.
On Sat, Feb 13, 2010 at 07:15:29PM -0500, Monty Montgomery wrote:
Ah, I am perhaps used to seeing... dirtier
implementations. Yes, it's
intended to just be an EQ. Do you have links to the specified
forward/inverse linear filters? I may not be thinking of a proper
implementation then.
Just two general-purpose first order IIR sections
is all you need for either the forward or inverse
filter. Any textbook on digital filters will tell
you how to program them. Inverting the LF filter
requires an extra pole below the audio range to
avoid infinite DC gain.
I didn't say that a digital filter couldn't
invert it (at least as
well as it can be inverted). I said that the typical digital EQ, the
kind you're going to find in any general purpose EQ plugin, is going
to be an acausal linear-phase filter.
The channel EQ you'll find on most digital mixers is
not linear-phase at all, nor acausal. In almost all
cases it's just first and second order IIR filters.
For plugins anything goes, but the most of them are
not linear phase, and no filter operating in real
time can ever be acausal - by definition.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !