26 Sep
2010
26 Sep
'10
9:45 a.m.
On Sat, September 25, 2010 10:48 am, fons(a)kokkinizita.net wrote:
On Sat, Sep 25, 2010 at 10:07:46AM -0700, Patrick
Shirkey wrote:
Just to clarify again, are you saying here that convolution will produce a
cleaner result than fft?
Or that the implementation of the fft algorithm in jamin is not the most
efficient method of doing the transform?
--
Patrick Shirkey
Boost Hardware Ltd.
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.
The confusion continues :-)
AFAIK Jamin does not have a parametric EQ. It uses an FFT-based
method with a graphical interface that makes it look either like
a combination of 'freehand' frequency response and parametric,
or as a 30-band 'graphic EQ'. But it's the same algorithm in all
cases, and it's not a plugin.
If works by taking the FFT of the input, multiplying in the
frequency domain by some precomputed values, and transforming
back using an IFFT. This modifies the frequency response of
course, but it is *not* a linear filter and produces side
effects (modulation). Jamin minimises this by 1) windowing,
which amounts to crossfading between processed blocks of
samples, and 2) processing much more overlapping blocks than
the minimum required to do crossfading (which would be 2).
The proper way to implement a filter of this type (with a FR
defined at all multiples of Fsamp / 1024) would be by using
linear convolution rather than cyclic. But as said, this is
not the right kind of filter anyway.