Subject: Re: [linux-audio-user] Resampling loop libraries
From: Frank Barknecht (fbar_AT_footils.org)
Date: Sat Apr 26 2003 - 14:14:59 EEST
Hallo,
Mark Knecht hat gesagt: // Mark Knecht wrote:
> Sox looks interesting. Quite a lot of capabilities there also.
>
> Maybe I need to do something to take advantage of the 'Acidized'
> feature of the loops also? Acid loops have tempo and root note info in
> the files. It would be nice to somehow be able to use that to get a
> better result.
In my understanding (which may well be much out of date) the Acid-info
is just meta-data to let Acid show things like bpm and such quckly.
So it's useless for time stretching or shifting (I use these terms
interchangably, which is technically not correct, I guess)
Normally stretching is done in one of these ways:
a) Resampling by changing the sample rate. This also changes pitch and
has artifacts, unless you do counter measures. Vinyl DJs do it a
lot in the analog realm.
b) rotating-tapehead delay pitch shifting. I think, Steve made a
plugin that works this way. You might use it for example with
ecasound. This is an old-fashioned effect and can be heard. Itself,
it only changes pitch and thus can undo the resampling
side-effects.
c) FFT-based pitch shifting. I think, Steve also made a plugin with
this approach (of course ;) It gives good results.
d) Granular resynthesis. This is used increasingly in commercial
software, for example Ableton Live is somehow a granular sample
player. The SndObj-library has a cool granulator called syncgrain
that I ported to a Pd external. As usual with granular synthesis,
you need to control a lot of paramenters, which can be difficult.
But simple loop-speed changing is rather easy with that.
ciao
-- Frank Barknecht _ ______footils.org__
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