[PD] about fiddle~

[Jamie Bullock]

Hi,

On Fri, 2008-01-11 at 13:57 +0100, matteo sisti sette wrote:

> Another question about fiddle.
> I'd like to be able to distinguish between a signal with a pitch and a
> signal without a picth. It seems to me that fiddle always outputs its
> "best guess" no matter how reliable it is.

Actually that's not quite true. fiddle~ doesn't output anything at all
from its first outlet unless it's pretty certain a pitch has been found.

However, it does continuously output the first estimated peak location
it uses to make its pitch calculation from its third outlet. It will
also output 0 as a peak location if it can't find a peak, so you can
make a pitched vs unpitched certainty estimator like the one in the
attached patch giving 3 certainty levels (0.5 is unsure). 

> I thought I may use the third outlet and evaluate whether it outputs a
> very randomly-varying number; however, with a [noise~] as input, it
> mostly outputs values between 90 and 110 and some 0 every once in a
> while.....

With the default fiddle~ settings, it seems to output 0 about 15% of the
time, which seems quite a lot to me.

Anyhow, I think this is a case of using the wrong tool for the job.
Pitch/f0 estimators (PDAs) are designed to find pitch in a signal, not
to measure noisiness. There are other tools to measure this - I find
spectral irregularity to be quite a good noisiness metric, but there are
several others. If you are interested in this, perhaps take a look at
the libxtract feature extraction library, which comes with PD external
that wraps its functionality.

Jamie

-- 
www.postlude.co.uk
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#N canvas 561 209 560 371 10;
#X obj 166 36 noise~;
#X obj 168 99 fiddle~;
#X obj 222 35 osc~ 440;
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#X obj 1 32 loadbang;
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