[Openal] Binaural recording + virtual 3D sound source + CMSS-3D

Tue Oct 20 01:47:17 PDT 2009

Hi Francois,

I believe that the XFi Platinum card will be able to do this - but I don't
think the Audgy 2 can.

With CMSS-3D 'On' (to enable the higher-quality 3D spatialization
algorithms) you can use an EAX 5.0 extension call to tell an AL Source
playing stereo content that it should not be upmixed.  If you are
interested in this approach then send me a private email and I can give you
the details.

Dan
Creative Labs (UK) Ltd.

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             Francois                                                      
             Montignies                                                    
             <francois.montign                                          To 
             ies at canterbury.ac         Daniel PEACOCK                      
             .nz>                      <dpeacock at creativelabs.com>         
                                                                        cc 
             10/14/2009 10:57          openal at opensource.creative.com      
             PM                                                    Subject 
                                       RE: [Openal] Binaural recording +   
                                       virtual 3D sound source + CMSS-3D   

Hi Dan ,

I am using a XFi Platinum, or sometimes an Audigy 2 for testing.
Please tell me that one of these two can play an OpenAL application with
HRTF [On] for mono source, without upmixing stereo source.
I really thought that upmix and downmix was only for nonOpenAL sound files.
I thought that stereo buffer in OpenAL application was not spatialized at
all, but it is still 3D virtualized if I understood well.

Could you explain me how the sound card (XFi for example) will spatialize
an OpenAL application when CMSS-3D is [off] ?

If both features (HRTF for mono buffer, upmix of stereo buffers) are linked
in CMSS-3D function, maybe could you give me a trick in the OpenAL code ?

Thank you,

Francois

HITlabNZ

-----Original Message-----
From: Daniel PEACOCK [mailto:dpeacock at creativelabs.com]
Sent: Thu 10/15/2009 3:44 AM
To: Francois Montignies
Cc: openal at opensource.creative.com
Subject: Re: [Openal] Binaural recording + virtual 3D sound source +
CMSS-3D

Hi Francois,

Which soundcard are you using?

>> When I enable Headphones CMSS-3D it adds a processing artifact on
>> my binaural recordings. I think it might be a cross-feed algorythm.

>> Is there a way to keep my original binaural track (that means left
>> channel to left ear, right channel to right ear) and add a 3D source
>> with CMMSS-3D "On" ?

The "CMSS-3D" feature includes upmix technology and enables high-quality 3D
Audio virtualization.
Depending upon the soundcard you are using it may or may not be possible to
separate these two
features unfortunately.

>> What would be the result if I turn off CMSS-3D and only select
"headphones" reproduction, do I
lose the HRTF for the virtual 3D speaker ?

I believe the answer depends on the soundcard you are using.

Dan
Creative Labs (UK) Ltd.

Notice
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privileged.  It is intended
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the intended recipient,  any disclosure,  copying or distribution of the
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taken by you in reliance on it,  is prohibited and may be unlawful.  If you
have received this
message in error,  please delete it and contact the sender immediately.
Thank you.

Creative Labs UK Ltd company number 2658256 registered in England and Wales
at 79 Knightsbridge,
London SW1X 7RB

             Francois Montignies

             <francois.montignies at canter

             bury.ac.nz>
To
             Sent by:
openal at opensource.creative.com
             openal-bounces at opensource.c
cc
             reative.com

Subject
                                                 [Openal] Binaural
recording + virtual 3D sound
             10/12/2009 05:07 AM                 source + CMSS-3D

Hi,

I would be really happy if someone could tell me if it is possible to deal
with binaural recordings
as background sound environments.
I work for a research project in which we only use headphones reproduction.
Binaural recording is
therefore a solution to have a realistic sound environment. We would like
to add a virtual speaker
with 3D coordinates that we can vary.

In my OpenAL source code I have :
- a stereo buffer for the binaural source (no spatialization with OpenAL)
- a mono buffer for the virtual source (3D definition with OpenAL)

Problem is :
When I enable Headphones CMSS-3D it adds a processing artifact on my
binaural recordings. I think it
might be a cross-feed algorythm.

Two questions :

- Is there a way to keep my original binaural track (that means left
channel to left ear, right
channel to right ear) and add a 3D source with CMMSS-3D "On" ?
- What would be the result if I turn off CMSS-3D and only select
"headphones" reproduction, do I
lose the HRTF for the virtual 3D speaker ?

Thanks for any help,

Francois,

HITlabNZ

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