[PD] Less intensive pitch shifting?

[Miller Puckette]

Hi Joseph et al.

First, I think you'll be lucky to get more than 3 voices of pitch shifting
on a 266 mHz. machine, and it doesn't matter much whether you're running
linux or Windoze.

It's probably best to allocate a fixed number of pitch shifters and
allocate them dynamically to the keys of your keyboard using the poly
object.  There isn't a simple example in the Pd doc of how to do this,
although #35 shows how to do it in a different situation where the note's
duration is known in advance.  


cheers
Miller

On Thu, Jun 13, 2002 at 09:24:31PM -0400, Joseph Zitt wrote:
> As I've mentioned, I working on a sort of "harmonizer" patch that takes
> an incoming signal and pitch-shifts it by appropriate amounts based on
> what keys are pressed on a 25-key MIDI keyboard. My first attempt uses
> 25 separate pitch-shifters, derived from the patch in the docs area,
> with the most recent velocity sent by each key determining the volume of
> the signal fed through that object.
> 
> (I don't know if this makes a difference, but I've replaced the
> half-steps-based calculations of the original with the simple frequency
> ratios of just intonation.)
> 
> Unfortunately, this appears to be beyond the capabilities of my somewhat
> lame laptop (266 MHz Pentium under Windows 98 (I'd rather use Linux but
> so far have had no success with the USB-MIDI driver)). When audio is
> turned on, the system slows down so radically that, from watching the
> numbers attached to the outlets of the notein object, a key press is
> processed some 2-3 seconds later, and what audio gets out is brief
> instants of distortion.
> 
> A couple of possibilities strike me:
> 
> - Is it possible to, in a sense, power down the objects when they are
> not being used (that is, when it has most recently received a non-zero
> control input)?
> 
> - Do less processing-intensive pitch shifters exist that the one I've
> modified (which uses the tape-head emulation to do the shifts)?
> 
> - Am I just more ambitious than my laptop can stand?
> 
> Thanks for any enlightenment.
> 
> -- 
> | josephzitt at josephzitt.com                 http://www.josephzitt.com/ |
> | http://www.metatronpress.com/jzitt/   http://www.mp3.com/josephzitt/ |
> | == New book: Surprise Me with Beauty: the Music of Human Systems  == |
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