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

[Francois Montignies]

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





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.

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             Francois                                                      
             Montignies                                                    
             <francois.montign                                          To 
             ies at canterbury.ac         openal at opensource.creative.com      
             .nz>                                                       cc 
             Sent by:                                                      
             openal-bounces at op                                     Subject 
             ensource.creative         [Openal] Binaural recording +       
             .com                      virtual 3D sound source + CMSS-3D   
                                                                           
                                                                           
             10/12/2009 05:07                                              
             AM                                                            
                                                                           
                                                                           




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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