[Pd] Complex audio signals

Chuckk Hubbard badmuthahubbard at gmail.com
Sun Jun 11 10:03:04 CEST 2006


I thought of trying something like this, but there are bound to be
some compromises, aren't there?  I mean, just from the inherent
compromises of FFT.  Unless, I suppose, you added the new imaginary
part to the original untouched real part.  And when you say
"continuous"... I guess you don't really mean "continuous" as in "not
discrete"...?

[czero~] is just that,
y[n] = x[n] - a[n] * x[n-1], which I take to mean:
Y[n] = X[n] - A[n] * X[n-1]

And so I'm thinking the real and imaginary parts of A[n] could be
anything at all, but I want to try and see.

-Chuckk

On 6/10/06, Charles Henry <czhenry at gmail.com> wrote:
> Hi, Chuck
>  The Hilbert transform does create a continuous complex signal from a
> real-valued signal, Y.  You take the Hilbert transform as 2*IFFT( X )
> where X is the FFT of Y with the second half of X replaced by zeros.
>
> This creates what is called the analytic signal, which has an
> identical real part to the signal we started with, and an imaginary
> signal that matches the real part.  There is exactly one imaginary
> signal to correspond to a real signal.
>
> You may find something in the examples about a Hilbert transform (but
> I don't trust it).  It would be pretty simple to just write another
> external for it (using the mayer fft).
>
> What's czero~ ?  Is that a filter with a zero, some place in the
> complex (Laplace) domain?
>
> Chuck
>
> On 6/10/06, Chuckk Hubbard <badmuthahubbard at gmail.com> wrote:
> > I'm teaching myself some DSP stuff, using Miller's Techniques, a
> > Digital Filters book, and some other references, and I'm loving it.
> > I am wondering, though, how one comes up with a complex audio signal
> > for use in Pd.  I want to experiment with [czero~], and I've also
> > wondered where complex signals come from for [fft~].
> > It doesn't seem like it would be possible to create a complex signal
> > from a real one, but maybe there are ways to synthesize them?
> >
> > Thanks.
> > -Chuckk
> >
> > --
> > "Far and away the best prize that life has to offer is the chance to
> > work hard at work worth doing."
> > -Theodore Roosevelt
> >
> > _______________________________________________
> > PD-list at iem.at mailing list
> > UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
> >
>
>
> --
> Charles Zachary Henry
>
> anti.dazed.med
> Med student who needs a Mickey's
>


-- 
"Far and away the best prize that life has to offer is the chance to
work hard at work worth doing."
-Theodore Roosevelt




More information about the Pd-list mailing list