[chuck-users] Time-stretching without changing pitch

[Kassen]

2008/4/27 mike clemow <gelfmuse at gmail.com>:

> Hey Kassen,
>
> I'm looking at the examples...  This is quite interesting.  I think
> you've mentioned LiSa a few times on this list before.


Oh, yes, I'm sure I did !


>  Could you
> maybe give a high-level overview of her for the uninitiated?
>

Sure. Atte is right in that she's basically a recorder with a variable
playback rate. There's a bit more going on as well.

LiSa can record incoming material which can then be played back. Playback
can happen while recording. She can also play back the same material with
multiple voices. All of these voices can have a attack and decay slope and
have loops as well in addition to their own start offsets and loop-points
and now even volume. Oh, and you can have feed-back.

That's may sound like the spec-sheet of a modest sampler (which is cool
already) but actually because we can code around her it's enough for
granulation, for delays, for convolution, pitch-shifting, time-streching,
you could do a slap-back echo....

So; a insanely versatile little Ugen. Dan Trueman made LiSa and he hasn't
gotten round yet to making a manual entry BUT there is a set of examples
that takes you through the basics up to more advanced techniques and ends
with "readme-2" which lists all of the member functions. I feel this is
actually very good documentation, more elaborate then some of the Ugens
which do have a manual entry and it's very practical. It's no secret that
I'm a fan of the examples dir as a way to get started with anything in
ChucK.

A fairly large section of these examples deals with techniques to avoid
clicks. If that's a issue for you you may also like to look up my post to
this list about using a SndBuf to record to LiSa while detecting and
indexing positive zero-crossings which can be used as another technique to
avoid clicks and other artefacts (with different strengths and downsides, as
always).

That should be enough to get you started, I think? There is of course no
substitute for simply spending a evening with her ;¬).

Yours,
Kas.

PS; in the interest of equal oportunities; Dyno is a guy, he's large and
green and friendly but he likes to squash things. We need more Ugens with
names that sound like individuals. This approach is 100% official and
definitely *should* be used in university cources ;¬).
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