hi Hans,
VBAP is probably better if you expect people to move around in the
installation space and you wish to pan individual sounds in different
directions.
First order ambisonics works fine on 6 speakers, but it would be more
suited to immersive, enveloping ambient sounds, or a more constrained
audience.
Horizontal VBAP will use only the nearest 2 speakers to simulate a
sound in one direction, while ambisonics decoding will generally use
all speakers for the same simulated sound source. Thus VBAP sounds
will often seem to "snap to speaker positions" when panning around the
circle, whereas ambisonic panned sounds will not reveal the individual
speakers as much, but the illusion will not work as well away from the
centre of the room.
I like the description I heard recently from Bruce Wiggins on the
difference between VBAP and ambisonics - that VBAP is exactly correct
for panning a sound when it's in the direction of a speaker, but quite
wrong when panning exactly in-between two speakers. Ambisonics on the
other hand is "equally wrong" (to a lesser degree than VBAP between
speakers) for a sound in any direction.
In many cases, the best spatialisation solution could be a mixture of
both VBAP (for directional sounds) and ambisonic (for spatial
ambience) - unless the audience isn't able to get too close to the
speakers, or you use higher order ambisonics.
The IEM ambi stuff is all in Pd extended browser... I guess you've
seen that.
I've attached some patches that I have for encoding to quad.
Only problem is the latest 2 releases of Pd extended seem to have
problems loading mtx_*~ object.
I got it working with Pd extended 0.39.3
Output is for 4 speakers, but it's easy enough to change the speaker
specifications in the nmg_bf2quad~ abstraction - go into the pd calc-
matrix subpatch, make up a new speaker spec, print the decode matrix
and copy that back into the patch.
Hope this helps.
Nick Mariette http://soundsorange.net
On Oct 6, 2008, at 6:39 AM, Hans-Christoph Steiner wrote:
So I am working on sound for a permanent installation involving 6 speakers in a large circular room. Are 6 speakers enough to do anything useful using ambisonics? Or am I better off using the simpler vbap?
I am just starting to understand the basics of ambisonics, thanks to Florian's intro. I will be programmatically controlling the position of the samples, since it will be synced up with a video. So I don't think I really need the GUIs like cubemixer.
Are there any simple, working demos of the IEM ambi stuff?
.hc
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