[PD] a phase vocoder pitch shifter harmonizer in real time

Charles Henry czhenry at gmail.com
Tue Jan 10 02:19:14 CET 2012

Hey Alex

I'm just trying this out.  I didn't have a sound file I particularly
wanted to try, so I just plugged in an osc~, and what I found on the
output:  a mixture of the original tone with the shifted one.

So, the shifted tone was clearly audible, but as I shifted the
frequency, I could hear first the beating of the tones then two tones.

And upon reading into the patch, that's clearly what you're doing in a
subpatch, but I don't get why?


On 1/9/12, Alexandre Torres Porres <porres at gmail.com> wrote:
> Hi Folks,
> working with these phase vocoder stuff, I thought I'd try and do a simple
> shifter/harmonizer with it once and for all. The phase vocoder shifter I
> found in pdmtl doesn't work as a harmonizer, and the latency was pretty
> high and not constant, so I did this. It's all as a Vanila abstraction!
> I have 2 short buffers (arrays) and do crossfade between them, I got some
> phase issues trying out and building it, but they now seem reasonably fine.
> I just did this, so I should work more on it to make it more stable and
> robust. I'm sure there are some bugs around, and it's still very dirty and
> needs code cleaning. Maybe I should try and implement it with delay lines
> as in pdmtl, hmmm, I guess it'd be better, right? Hmm... Later on when I
> have the time...
> Anyway, this goes back to the Pd Shifting thread I started here a while
> ago. I really like the quality of the phase vocoder. Somehow I don't get
> interested so much on other techniques and such. Yes, I assume there are
> some advantages out there, so what exactly would I be missing?
> Well, Check this thing I did out, see what you think, let's talk some more
> about pitch shifting....
> get it here: http://sites.google.com/site/porres/pvoc-shifter.zip
> I wish to officially release it along with some other tools I'm building
> for my PhD, soon to be over...
> by the way, I see this object is finally available
> http://www.katjaas.nl/pitchshift/pitchshift.html need to try it out.
> cheers alex

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