25 Sep
2010
25 Sep
'10
7:07 p.m.
On Sat, September 25, 2010 7:17 am, fons(a)kokkinizita.net wrote:
On Fri, Sep 24, 2010 at 09:51:07PM -0700, Patrick
Shirkey wrote:
Thanks for clarifying. I recall the parametric eq was chosen because that
was recommended as the tool to use by the professionals mastering
engineers who were contributing to the development discussions.
IIRC Fons suggested the sc4 compressor algorithm
was similar to a
vocoder.
I did never suggest anything of the sort concerning the sc4 compressor.
More precisely, the * FFT-based equaliser * is not a linear filter but
a vocoder. You just have to inspect the code to see this. The problems
resulting from this are mitigated to a large extent by using a large
overlap factor, at the price of much increased CPU usage. To the point
that a real filter implementation using linear convolution would in fact
be simpler and more efficient.
If this were all I'd have provided a patch years
ago. But there are other
problems with this type of filter: it provides way too much detail in the
mid and high frequency regions. There is really no point in having any
significant gain difference between say 4000 Hz and 4020 Hz, the only
result would be a very bad impulse respons that destroys all transients.
Yet the user interface makes it easy to get this sort of thing, even just
accidentally. It's a good example of textbook DSP being applied blindly
and without understanding the consequences.
To clarify further, are you referring to the entire ui or specifically to
the parametric eq ui which Jan designed? I think Jan would be the first to
admit that he is not a dsp expert but was instead attempting to provide a
user friendly interface for the specific plugin.
If the latter, it's trivial from a backend perspective to add a linear
filter in place of the parametric eq. After all it is just a ladspa plugin
with a custom gui. No doubt you have already released one. The much more
complex problem will be adding a frontend that allows for proper control.
However if the interface is similar to the parametric eq ui it is probably
only a weeks work or less.
Do you have an example of what the ui for a linear filter should look like
from an ui perspective?
I could look around online for example but no doubt there is a correct way
to represent it so I would rather see that first.
IIUC there is nothing to stop us from adding a linear filter as an option
for the eq section.
--
Patrick Shirkey
Boost Hardware Ltd.