The abillity to perform quad sound with some
multichannel card is one thing... But what I was
heading for is 3d spacial audio (height included) as
discribed in the ambisonics homepage, which is more
than distribution of sounds in space just by a quad
mix, based on amplitude (like panning in the stereo-
field): What they discribe convincingly is some
psychoarcoustic shaping of the sound material, so
that amplitude distribution is one part,
freq-dependent response (which seems to mean, that
the distribution of sound is frequency-dependent, in
correlation with the amount of phase shifting
required for precise spatial localisation. It may
even include the head-related transfer-function (hrtf).
All this may give a more precise localisation for
hopefully many listeners (not just the one in the
middle). See ambisonics homepage for reference:<
http://www.york.ac.uk/inst/mustech/3d_audio/ambison.htm>

Now- isn't this possible to do in a c-sound-file? To
generate the surround sound according to a score in
an instrument , which contains this psychoarcoustic
processing as a "module", that is applyed like any
other filter or reverb? output is then 4-channel, but
contains more spacial information than just an
amplitude-based 4-channel-mix.
Has anyone used such thing? Maybe there are really
some scores/orc. arround, that (I thought) I had
heard of. They should be at the ambisonics page, but
they are not anymore. Or maybe I got the whole
ambisonics page wrong? 
Who has experience in that?

greetings


Jan Jacob





---Richard Dobson  wrote:
>
> The SB live is designed to generate surround audio
from a mono or stereo
> source, which is what the games people want. The
fact that you get a
> quad ~output~ does not necessarily mean you can
give it a quad ~input~.
> 
> Any card which provides a single quad WAVE device
can be used by Csound
> to play a quad file.
> 
> The free Multi-Channel Toolkit (Win32 console)
available from the CDP
> website includes a program 'playsfx' which will
report the number of
> channels supported by each WAVE device on the
system. Where N channels
> are supported by a device, playsfx can play an
N-channel file.
> 
> More to the point, if a device supports a quad
file, you can play the
> file using Media Player - you don't need any
third-party application.
> 
> Unfortunately, some cards (where the driver-writers
were lazy) will
> acccept a quad file even when they shouldn't - it
may come out at half
> speed, or worse.
> 
> Richard Dobson
> 
> 




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i just want to clarify a few things about ambisonics (and why its so cool)

- only 4 channels of data for full periphonic surround - and you can have
ANY number of playback speakers in any location (obviously the more you
have and the more equally spaced the better). 

- it uses no psychoacoustic filtering like HRTF - it doesnt need to
because it is trying to recreate the actual sound field in 3D space at a
particular point (the center of the speaker array) -  its not using some
kind of  "evil trickery" to fool your brain 

- and as opposed to HRTF, localization within the sound field stays in the
same place when you turn your head!

- ambisonics (and B-Format[WXYZ] that it is normally stored in) is
elegant and simple in principle, which has the bonus of being 
computationally efficient - rotating sounds and other spatial
manipulations are done much easier in ambisonics than HRTF.

- full 3D ambisonics (B-fromat) takes up smaller space (4chnls) than dolby
5.1(6chnls) - dolby 5.1 isnt reall "3D" anyway - no hieght -

- if you ever get a chance to hear it, there is no comparison to dolby.
with ambisonics, the speakers become "invisible" and you really are
immersed in a "virtual" sonic environment.  

- 

- matt





On Thu, 19 Aug 1999, Jan Jacob Hofmann wrote:

> The abillity to perform quad sound with some
> multichannel card is one thing... But what I was
> heading for is 3d spacial audio (height included) as
> discribed in the ambisonics homepage, which is more
> than distribution of sounds in space just by a quad
> mix, based on amplitude (like panning in the stereo-
> field): What they discribe convincingly is some
> psychoarcoustic shaping of the sound material, so
> that amplitude distribution is one part,
> freq-dependent response (which seems to mean, that
> the distribution of sound is frequency-dependent, in
> correlation with the amount of phase shifting
> required for precise spatial localisation. It may
> even include the head-related transfer-function (hrtf).
> All this may give a more precise localisation for
> hopefully many listeners (not just the one in the
> middle). See ambisonics homepage for reference:<
> http://www.york.ac.uk/inst/mustech/3d_audio/ambison.htm>
> 
> Now- isn't this possible to do in a c-sound-file? To
> generate the surround sound according to a score in
> an instrument , which contains this psychoarcoustic
> processing as a "module", that is applyed like any
> other filter or reverb? output is then 4-channel, but
> contains more spacial information than just an
> amplitude-based 4-channel-mix.
> Has anyone used such thing? Maybe there are really
> some scores/orc. arround, that (I thought) I had
> heard of. They should be at the ambisonics page, but
> they are not anymore. Or maybe I got the whole
> ambisonics page wrong? 
> Who has experience in that?
> 
> greetings
> 
> 
> Jan Jacob
> 
> 
> 
> 
> 
> ---Richard Dobson  wrote:
> >
> > The SB live is designed to generate surround audio
> from a mono or stereo
> > source, which is what the games people want. The
> fact that you get a
> > quad ~output~ does not necessarily mean you can
> give it a quad ~input~.
> > 
> > Any card which provides a single quad WAVE device
> can be used by Csound
> > to play a quad file.
> > 
> > The free Multi-Channel Toolkit (Win32 console)
> available from the CDP
> > website includes a program 'playsfx' which will
> report the number of
> > channels supported by each WAVE device on the
> system. Where N channels
> > are supported by a device, playsfx can play an
> N-channel file.
> > 
> > More to the point, if a device supports a quad
> file, you can play the
> > file using Media Player - you don't need any
> third-party application.
> > 
> > Unfortunately, some cards (where the driver-writers
> were lazy) will
> > acccept a quad file even when they shouldn't - it
> may come out at half
> > speed, or worse.
> > 
> > Richard Dobson
> > 
> > 
> 
> 
> 
> 
> _________________________________________________________
> DO YOU YAHOO!?
> Get your free @yahoo.com address at http://mail.yahoo.com
> 
>