[PD] Spectral focusing

eran at mx.kein.org eran at mx.kein.org
Sat May 28 11:14:20 CEST 2011

@ William Brent: William, I'm a big fan of tID - what an incredible
library! I've used it for several projects this year. So first up - big
I was able to get some interesting results from the bark-vocoder(not at
all robot like!), with replacing the [osc~]s with [vfc~]s and tracking the
fundamental of a harmonic source with [sigmund~].
But this still sound like imposing the harmonic characteristic on an
existing spectrum, while I think I am looking to arrive at harmonicity
through something like moving the frequencies of the partials into their
closest values according to the harmonic series (so moving from

Can this be done? it would entail changing the frequency of each bin
A related procedure would be non-linear spectral stretching, which I also
could not find in my searches through pd-world.

@ Peter Plessas: Miller's timbre-stamp is totally cool, but if I
understand it correctly it changes the spectral contour of the sound by
replacing the amplitudes of the respective bins, but as is the case with
fft, the frequencies of the bins are determined by the analysis-size so
they remain the same for both sounds. And while this sounds great I think
I'm looking to change the frequency of each partial in a way that isn't
tied with the discrete frequencies of the bins..

This is what got me curious about Wishart's way of using lpc - he says
that you can set the coefficients according to pitch relations, though I
still dunno how to do this in pd, argh...

Thanks guys,

> Hi Zax,
> Maybe a straight up vocoder is too primitive for the kind of sound
> you're after, but who knows...  For what it's worth, I have a vocoder
> patch in my timbreID examples package with filters that are spaced
> evenly in Barks.  You can also tune the relative amplitudes of the
> filter outputs.
> Of course, it still might just make everything sound like a robot :)
> On Wed, May 25, 2011 at 9:24 PM,  <eran at mx.kein.org> wrote:
>> Hello list,
>> After a few years of maxing I migrated back to PD about a year and a
>> half
>> ago and haven’t looked back.
>> Now I ran into a stumbling block and I figured I turn to you for help:
>> I’m looking for a way to impose a harmonic spectrum on a non-harmonic
>> signal. I tried cross-synthesis with a harmonic signal, which is ok, but
>> what I’m actually trying to do is to “tune” a field recording, in a way,
>> so it can have harmonic relations to a live instrument.
>> I played with the pvtune~ object from fftease which is nice, but the
>> results end up sounding a bit autotune-ish. And I also tried driving a
>> few
>> vcf~ filters with frequencies running from fiddle~/sigmund~ but the
>> fundamental from these objects is too erratic and it sounds very
>> unnatural.
>> Wishart describes in his book a technique he calls spectral focusing,
>> which relies on lpc. He says that lpc can be set to generate a filter
>> bank
>> which is distributed evenly with respect to pitch, but I’m not sure I
>> understand what he means and how it can be done in PD. lpc seems to
>> output
>> a set of amplitudes for the coefficients. Can I set the filters to
>> frequencies of my choice?
>> Any help with this would be greatly appreciated,
>> Zax
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> --
> William Brent
> www.williambrent.com
> “Great minds flock together”
> Conflations: conversational idiom for the 21st century
> www.conflations.com

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