DP Spectral Effects causes distortion

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David Jaggard
Posts: 5
Joined: 12 Aug 2006, 02:40
Location: Paris France

DP Spectral Effects causes distortion

Post by David Jaggard » 17 Aug 2009, 22:48

Thanks to the recession, I'm still using Digital Performer 4.61 on a G4 (OS 10.3.9, 350 MHz, 512 Mo SDRAM). I have a series of spoken voice tracks that I want to "morph" using Spectral Effects to make them sound like different people speaking. Problem is, if I raise the pitch more than one semitone I get distortion. LOTS of distortion, but only on certain words. And those words seem indistinguishable from the others in terms of timbre, level, quality, pitch stability, inflection, etc., etc. Doesn't matter if the signal is stereo or mono or if I switch the preference in the Sounbites window from DSP to standard pitch shift.
Anyone know what to do to avoid this problem?
Thanks !
If anyone happens to be interested, my compositions and humor writing can be seen at http://mapage.noos.fr/qoo

biomuse
Posts: 156
Joined: 24 Aug 2006, 10:03
Location: San Francisco

Re: DP Spectral Effects causes distortion

Post by biomuse » 21 Aug 2009, 08:20

I've rarely ever used formant correction in DP, only pitch correction for sung vox, but my experience with that has been that I occasionally get distortion when I pitch edit in a way that messes with the the original pitch contour of the voice, much more so than does the amount of pitch change I apply; if I work with instead of against the natural contouring and use the decrease modulation function (option-click on the pitch grid) to reduce pitch wavering, I can reliably avoid all distortion (and the results sound natural).

But in this case I don't think you are editing pitch on a note-by-note basis, right? You're just shifting whole tracks en masse?

I remember doing this kind of thing once years ago, in a situation where I needed to turn some of my own sung background vox into female vox. I remember getting some distortion at first, and just messing with the formant change a cent at a time; the distortion went away with a small value change after a few tries. I couldn't mess with pitch too much, because these were sung and not spoken vox.

I would suggest trying small shifts in formant correction and pitch correction until the distortion goes away.

But also, keep in mind that DP's algorithm is designed to work best with pitched (sung or played) material rather than spoken word according to the manual. There are other algorithms that may be better suited to shifting of largely unpitched material:

-The Apple AU Pitch plugin (comes with Macs) works very well for simple pitch shifting. You could use this in combination with DP's formant shifting and see if you get cleaner results with spoken vox.

- Also free: http://www.audiowish.com/audio-units/oc ... ifter.html. Again, could try in combo with DP's formant shifting.

- Also have a look at Reaper. Free/cheap, and it has a pitch shifter that is pretty well-regarded, although I haven't tried it myself.

You may also want to post your question at Motunation.com, which has a well-informed and highly populated DP user forum; there may be people there with more experience than myself at altering spoken word material.

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