Subject: Re: [linux-audio-dev] [ann] unmatched - a LADSPA amp tone
From: nikodimka (nikodimka_AT_yahoo.com)
Date: Thu Oct 24 2002 - 16:27:59 EEST
>> my feeling is that oversampling alone will not do, although
>> you're probably right in that it will get rid of most of
>> the aliasing.
>
>Its how most people tackle to problem. I think I can get the valve cheap
>enough that it will be practical.
I'm not really familiar with what are the techniques of anialiasing
in use. But I can see the following way.
You can calculate your tranformation for the input signal S(x_i) once
And the same transformation for S(x_i)+1 again.
I mean two similar input signals differing in one bit of value.
So when you have two output saignals you can calculate
the error due to aliasing: abs( F(S(x_i)) - F(S(x_i)+1) )
And apply some techniques to eliminate this aliasing
ranging from qubic splines to plain dithering applied to
the output signal.
It seems to me that this is much better than oversampling.
Especially for nonlinear transformations.
(Or is it just a trivial thing and it doesnt work and
this is not what you discuss?)
nikodimka
>
>> i'm thinking about how to apply the technique to produce
>> square clipping, or better a [0 .. 1] range of clipping,
>> but the integration approach is awkward.
>
>I doubt that the electronics ever produces hard square clips.
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