[Clam-devel] CombFilter and GenderChange

[David García Garzón]

On Diumenge 15 Abril 2007, Xavier Amatriain wrote:
> I wasn't asking for the file you changed to make it work :) My question
> was whether you had any hints on what made it NOT work. Did the Pitch
> Shift stop working due to your latest work on the Gender Change or is it
> something that has been down for much longer. In any case, don't worry
> too much, I have a working copy and I will be able to figure it out as
> soon as I have some time.

I told you about the U shaped output of the gender change when we were at 
Santa Barbara, so the bug is there for long. But as the transformation has 
been working ok on the SMSTools, i supose that it is something related to 
making it work on the NetworkEditor. The tipical issues i found when doing 
this are:
- Suposing inplace modifications when it is a new object (ugly but fast 
solution: copying it and proceed)
- The copy is done but at some higher level (segment or frame) as NetEditor 
deals with the low level objects, the copy is not done.
- Copy is not needed but some format (log/linear, magbuffer/comples...) on the 
output is expected but default objects are obtained from the port. In this 
case, as Pau said, the solution is to prepare the output on the Do().


> > Another issue i don't understand is why comb filter is filtering target
> > frequencies (i*fundamental*amount) instead source frequencies (just
> > i*fundamental).
>
> I guess my explanation the other day was not quite accurate. The
> feedforward delay resonates frequencies that are integer multiples of
> the target pitch and filters out the rest (with local minimums at odd
> multiples of target/2). So, it's not that you are exactly filtering out
> the original but rather resonating the target in the residual.

So i am listening frequencies of the old pitch. It seems to be an analysis 
problem, not detecting the proper fundamental and then letting some harmonics 
getting out of the shift. I cannot check whether the combfilter minimizes 
that because the introduced noise does not let me listening  frequencies. 
Whatever the filter resonates, resonates it a lot ;-)


-- 
David García Garzón
(Work) dgarcia at iua dot upf anotherdot es
(Home) vokimon at telefonica adot net
http://www.iua.upf.edu/~dgarcia
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