Re: On 8 speakers


Subject: Re: On 8 speakers
From: Chris Rolfe (rolfe@sfu.ca)
Date: Tue Jan 26 1999 - 02:07:20 EST


I wrote the software for the system Darren and co. are using, so maybe a
word or two here about design philosophy wouldn't be out of place.

The user can specify angle placement for any given input. The speaker map
is edited separately, the idea being that you might want to pan a sound
from 10 degrees to 190 degrees, and not be worried about speaker location.
Speaker maps are simple graphic documents that record the current venue
speaker locations.

On the other hand, sometimes the allocation of an input channel to an
output channel is important, say an assign to global reverb. In that case,
you're free to override the speaker map and assign directly to the output.

The idea was to liberate the diffusion composition from the particular
placement and number of speakers.

The biggest trick is to get composers to work in 8 channels. We're all so
used to reducing to stereo that we fail to compose in space. The greatest
mistake I see is that composers tend to reduce everything to a "flying
object", when in fact there are very few sounds that pan successfully. 8
discrete channels are, however, a wonderful thing to hear.

As far as the speaker layouts proposed (circular vs. stereo side/side) I
would suggest that the difference is trivial. While there are some
spatialization techniques that rely upon equidistant speakers (favouring
the circle approach), 99% of the audience is outside the sweet-spot, and so
a few degrees here or there doesn't matter. In general, the equidistant
circle is preferable, but the rectangular-shape doesn't irreparably damage
a well-diffused piece.

Remapping DVD (5.1 and relatives) is a different question, of course.
Generally, DVD is "super-stereo", that is, stereo tracks are de-correlated
to provide max bang-fer-buck for the high-end home theatre. The
de-correlated signals are, however, usually manufactured from the original
stereo+sub track.

If I get the idea, conforming one's works to DVD would be smart. Exploring
what and why one would pan a sound 180 degrees, or split a compositional
idea across two speakers would be more productive and interesting.

Chris

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