29 Sep
2010
29 Sep
'10
2:44 p.m.
On Tue, Sep 28, 2010 at 06:44:09PM -0700, Patrick Shirkey wrote:
The fact that this *can* be done does not imply it *has* been done
correctly in this case.
On Tue, September 28, 2010 8:22 am,
fons(a)kokkinizita.net wrote:
Thas nothing to do with optimisation. The algorithm is wrong. It does
not do what you think it does and what the designers probably intended
it to do. The correct one is not much different, but differs in some
essential points.
The implementation is fundamentally wrong. Just
send a sine wave through
it, measure the result and ask yourself how a *filter* could ever produce
the broadband junk that this one is adding.
Well if this is the case the implementation needs optimisation. That
doesn't change the fundamental nature of the design choice. Don't you mean an optimised implementation of the
filter?
No. I mean a correct implementation.
My concerns
are not about the optimisation. For there isn't any. I repeat:
the implementation is fundamentally wrong, the method used does not only
filter but it also adds distortion, and most of the CPU power used by the
filter is used just to reduce the problems that result from this.
How can it be fundamentally wrong if all linear convolution operations can
be expressed in the the transformed domain, and vice versa. If there is a problem it is not due to the fundamental
nature of the
linear filter.
I'd suggest you stop calling this a linear filter for it isn't.
But I will query your analysis first because it may be
that we are talking
at cross purposes.
IMO what you have identified is the potential for optimising the code.
No. Although a correct implementation would indeed use less CPU.
This is definitely something that should be addressed
if it indeed turns
out you are correct in your analysis.
Although I have strong reservations given that 3 different DSP engineers
with qualitatively more experience than you can justify this design
choice.
Then let them speak up. I've posted the technical arguments before and
nor you nor any of your experts has so far commented on them. And as to
my level of experience, I don't think you have any correct idea of that.
I've a nice collection of measurement results for Jamin, maybe I'll
publish a few of them and then your experts can try to explain them.
Ciao,
--
FA
There are three of them, and Alleline.