[PD] Less intensive pitch shifting?

[Joseph Zitt]

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.

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