A pitchshifter mid level module?

Shifrin · 17 Jan 2006

Hi Tambra and welcome to the forums 🙂

You might find this link has some useful information in it :-

Bending the pitch without the pitch bend

Shif.

sambean · 17 Jan 2006

Welcome tambra!

I have an updated version of my harmoniser available with this chorus, it can be used to stretch the pitch +/- 1 octave, quality's quite crude though..

Cheers

Sam

tambra · 17 Jan 2006

Thank you Shif and Sam.

The quality is still quite ropey, but again may be useful as an effect.. We'll probably need to wait until we get the FFT in code before we can do higher quality scaling..

What about this point today? May I deduce that a hight quality pitchsift is almost FFT based? 😕

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angstrom · 17 Jan 2006

you can do an ugly sounding but servicable pitch shift in the time domain, taking slices and slowing them down or speeding them up (like an analogue-style delay) then x-fading those chunks. useful for somethings, most old guitar-pedal pitch shifters were like this.

oddson · 17 Jan 2006

you can do an ugly sounding but servicable pitch shift in the time domain, taking slices and slowing them down or speeding them up

So that would be a 'granular' solution... right? Is that what' Sam's first pitch shifter was doing? It sounded pretty good to me but I only ever tried it with fairly static wave shapes.

angstrom · 17 Jan 2006

hmm, that harmoniser example produces a different output to what I'd expect and I am unfamiliar with that method. So I guess it is similar but different, I am guessing that the harmoniser method is an improvement upon the basic granular aproach.

this is what I am talking about http://crca.ucsd.edu/~msp/techniques/la ... de105.html

Tom7777 · 17 Jan 2006

Welcome to the forum tambra 🙂

sambean · 18 Jan 2006

😀 The harmoniser is based exactly on that method.. I'm not sure how to do pitchshifting better than that in the time domain.. Have you tried the harmoniser that comes with the 2nd chorus?

Cheers

Sam

skOre · 18 Jan 2006

Welcome.... to the fooorummmms!

tambra · 18 Jan 2006

I were an eventide user. I've worked with an H8000 during few month. It get the higher quality pitchshifting algorythm I've ever heard at the moment, and it seems to be time strech based in fact. So may we look seriously in this direction...

Have you tried the harmoniser that comes with the 2nd chorus?

Not yet but I'll do it soon.

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doug4350 · 18 Jan 2006

While we're on this topic, I had an idea or a different approach to the problem, while thinking how it's done electronically...

With my little knowledge of dsp, I may be pissing into the wind or reinventing a square wheel 🙂 .

Why couldn't the signal to be shifted be fed into a vco with a "shift factor" and then de-mod'ed to recover the shifted signal??? I suppose this could be done a.m. wise with a vca, but just sparking ideas outloud. It seems SM is missing a de-mod component/module, or I haven't found that closet yet 🙂 . I suspect (thinking as a programmer) there isn't one, and would require some work on the dev's part to create a pitch shift component using this method.?.?

Any thoughts folks???

Aloha, Doug

rl · 19 Jan 2006

you mean AM as used in radio broadcast transmiton? In this case demodulation is usually done by filtering the modulation frequency (and the unwanted sidebands) away.

doug4350 · 19 Jan 2006

you mean AM as used in radio broadcast transmiton?

Yep, that's the one... I was speculating how the vco is cranked... flushing a wave table || timeslicing a running (composite) wave || voodoo 🙂 .

I mentioned the dev's because I wonder if the osc components could be coded in reverse to act as a demodulator sort of... I have a feeling this is a taLL order though.

Aloha, Doug