[Pd] Complex audio signals

[Chuckk Hubbard]

On 6/20/06, Piotr Majdak <piotr at majdak.com> wrote:
> Hi chucck,
>
> Chuckk Hubbard wrote:
>
> > On 6/20/06, Piotr Majdak <piotr at majdak.com> wrote:
> >
> > Writing the original signal and the real and imaginary parts of the
> > output to graphs shows lots of alterations.  It is fine with a block
> > containing an integer number of cycles, but otherwise gets weird
> > results.  See attached.
>
> Every time you write the signals to the tables, the phase of the original signal
> changes. Because of the windowing effects the processed signal (FT->Re{}->IFT)
> changes dramatically: the real part of the FT result contains the information
> about the symmetric part of the original signal (=cosines), which changes with
> its phase.

So it doesn't work.
I mean, I understand, with a rectangular window there are
discontinuities that read as crazy frequencies, but essentially this
doesn't work for supplying the imaginary part.
I guess it's just academic now, but I'm still curious.

-Chuckk

>
> Thanks for the nice example - it took me a while to analyze what happens here.
>
> br, Piotr
>
>
> --
> Piotr Majdak
> Institut für Schallforschung
> Österreichische Akademie der Wissenschaften
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> A-1010 Wien
> Tel.: +43-1-4277-29511
> Fax: +43-1-4277-9296
> E-Mail: piotr at majdak.com
> WWW: http://www.kfs.oeaw.ac.at
>
>
>
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