"Jean-Michel DARRÉMONT" wrote:

> Hi,
>
> Reading the book:"Conversing with Cage" from Richard Kostelanetz I noticed
> Cage's commentary about his
> realisation of Williams mix in 1952.
> They choped up a recorded tape in 1097 fragments and spliced them back into
> the band.
> In that way they put the splices in any orientation refered to the normal
> horizontal reading.
> The splices where played mainly diagonaly.
> He said that the sounds produced that way were "perfectly beautiful sounds" no
> doubt they are at least quite unusual.
> Here comes to mind this question: how can a soundfile be read in CSound at a
> variable angle saying that 0° is the normal playback, 180° backward and 360°
> normal playback again?
>
> It would be interesting to try this, specialy when we consider they spent one
> year with a five or six persons team to realize Williams Mix, cutting,
> splicing tiny pieces of tape, using chance operations to determine length and
> angle of reading in a terribly meticulous work.
>
> Digital synthesis could do that in a clic and that way experience and bring
> the process further.
>
> Is hetro/adsyn necessary or pvoc or something simpler?
>
> Any idea?
>
> Regards.
> --
> Jean-Michel DARREMONT

Jean-Michel:

The forwards and backwards part is easy since you can use any index into a stored
sample as long as the table length is a power of two in size.  In other words,
use GEN01 and set the size of the table rather than letting Csound set it to the
actual length of the soundfile, which is rarely a power of two.  At this point,
you can index this with something like a sinusoidal sweep that moves through the
file forward, slows to a stop, and then proceeds backwards through the file,
etc.  If you want angles other than 0, 180, and 260, then you have to multiply
the outputs of several indexed tables to create a three-dimensional terrain (wave
terrain synthesis).  Then you can truly move through a file with any angled path.

You can read a bit more about this in the Roads Computer Music Tutorial.  I also
have a Csound implementation of this instrument that I can dredge up if you
like.  The one bad thing about this sort of synthesis is that you get a lot of
additional sidebands (especially since it is a bit like synchronized FM with the
results ring modulating each other---also a bit like waveshaping, depending upon
how you index the two (or more) files).  Let me know if this sounds interesting
to you and I will post the wave terrain instrument files again.  It works fairly
well on short samples.  I have yet to find the right (if there are any)
parameters for a good sounding wave terrain synthesis of longer samples.

with warmest regards,
Jon

Jon Christopher Nelson, Director
CEMI: Center for Experimental Music and Intermedia
University of North Texas College of Music
PO Box 311367
Denton, TX 76203-1367
ph. (940) 369-7531
fax (940) 565-2002
jnelson@sndart.cemi.unt.edu