[PD] www.pd-tutorial.com
Frank Barknecht
fbar at footils.org
Wed Mar 18 09:17:17 CET 2009
Hallo,
Kyle Klipowicz hat gesagt: // Kyle Klipowicz wrote:
> Frank, I'm curious about how you use list objects in composition. I'd love
> to see a little etude from you about that whenever you find the time. You
> always make such clear, concise, and fun instructional patches.
That's flattering so I guess I should give an example. ;)
[list] of course is useful for lots of stuff, e.g. as a general
container for messages (it's central for sssad in this regard), to
convert meta-messages to lists and back, etc.
In composition list-operations let you encapsulate many common tasks
in reusable abstractions. Johannes mentions LISP in his book, which
is the mother of all list-based composition software, but you can do
lots of stuff in Pd as well thanks to list.
As an example attached are abstractions that do four transformations
of little musical motives. The motives are stored as lists of numbers,
where each number represents a scale step. In the example a major
scale is used, but you can do 12-tone serialism as well and also apply
the transformations to rhythm lists etc.
The four operations demonstrated are:
- retrograde: play a motive backwards. That's a simple [list-rev] from
the [list]-abs (included)
- transpose: add a number to each list-element. I used [list-map]
here.
- inversion: That's a bit more complicated. Quoting Wikipedia:
Inverted melodies
When applied to melodies, the inversion of a given melody is the
melody turned upside-down. For instance, if the original melody has a
rising major third (see interval), the inverted melody has a falling
major third (or perhaps more likely, in tonal music, a falling minor
third, or even some other falling interval). Similarly, in twelve-tone
technique, the inversion of the tone row is the so-called prime series
turned upside-down.
http://en.wikipedia.org/wiki/Inversion_(music)#Inverted_melodies
In inversion.pd this is realised by walking through the list with
list-map, taking the difference between the current element and the
previous element, then substracting this from the current element.
The first element in a list is treated specially as it has no
previous element (it's just copied).
- retro-inversion: that's just a retrograde followed by an inversion.
As we have abstractions for both not, just bundle them in another
one.
list-compose.pd show all four operations in use to transform a little
motive.
(This text is available online as well at:
http://footils.org/cms/weblog/2009/mar/18/using-list-composition-pd/
)
Ciao
--
Frank Barknecht Do You RjDj.me? _ ______footils.org__
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