[Openal] Question about Motu 828mkIII hardware

[Daniel PEACOCK]

Which OS are you using?  What ever it is, as long as it lets you enumerate
(discover) each of the soundcards and allows you send audio to it, it
should be possible to send both soundcards an audio stream from the same
application.   On Windows this is definitely possible.

(One of) the tricky part(s) is going to be getting the audio to start
playing at the same time (or close enough to the same time) on the 2
soundcards so that you don't get some noticeable delays as a sound pans
from a speaker controlled by soundcard A to a speaker controlled by
soundcard B.

Once you have defined a speaker layout and know which channels of which
soundcard refer to each location you can create your 12.2 mix and send each
6.1part to the appropriate soundcard.

Dan
Creative Labs (UK) Ltd.

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             Jason Daly                                                    
             <jdaly at ist.ucf.ed                                             
             u>                                                         To 
                                       Serge Lages <serge.lages at gmail.com> 
             04/02/2009 04:28                                           cc 
             PM                        "openal at opensource.creative.com"    
                                       <openal at opensource.creative.com>,   
                                       "dpeacock at creativelabs.com"         
                                       <dpeacock at creativelabs.com>         
                                                                   Subject 
                                       Re: [Openal] Question about Motu    
                                       828mkIII hardware                   
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Serge Lages wrote:
> Hi Dan and Jason,
>
> Thanks for your replies. I am a real newbie about sound development so
> please excuse me if my questions are a little dumb... :/
>
> If I understand it well, having a single 12.2 system managed with 2
> cards will be difficult (but possible).

Just to clarify, you'll have to edit the OpenAL implementation (the
library) itself to do this.  Since you're a self-described newbie, it
might not be the best solution for you (no offense intended ;-) ).

If you do want to give it a try, Chris Robinson's OpenAL-Soft
implementation would be the best starting point.  You can get it at:

   http://kcat.strangesoft.net/openal.html


> And what about having a single application managing two 6.1 systems ?
> Or even two applications, one for each card, then I can make them
> communicate to know where to play the sounds.

You can certainly open two devices and contexts in OpenAL.  The problem
is that the implementation will assume a typical 6.1 speaker layout (a
la Dolby Surround EX) for both contexts, and there is no way (that I
know of) to tell it where your speakers are.  There will always be sound
coming from at least one speaker, even if all of your speakers are on
the left or right side of the room.

You're not the first person with a non-standard hardware configuration
like this, but unfortunately, I don't remember anyone contributing an
implementation for your kind of use case, even though the OpenAL API
would be the perfect interface for it.

--"J"

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