[Openal] Multiple local players

[Chris Robinson]

On Saturday 24 November 2007 09:39:43 am Charles Pence wrote:
> Hello list--
>
> Has anyone ever attempted a OpenAL-based sound solution with multiple
> local players?  I know having "two listeners" isn't supported by AL, but
> is there some cheap-trick method that one could conceivably use to fake
> the illusion of more than one listener on the local machine?

Technically, you can create more than one listener. Just create multiple 
contexts (one context = one listener). Unfortunately, the OpenAL spec doesn't 
gaurantee being able to create more than one context per device. 
Alternatively, you can simply open two devices and get a single context from 
each. This, however, may not work on Windows (judging by the old Windows 
source, the mixer has improper assumptions about the current context), and it 
will *not* work using the SI (Unix implementation).

The (psuedo-)good news is that OpenAL Soft does work correctly with multiple 
devices/contexts. As long as your card/driver supports it, just open the same 
device twice, and get one context from each. Each context will then be one 
listener. Make sure to set the correct context before manipulating its 
sources, and you're good.

Hopefully OpenAL Soft will become the "default" Unix implementation. It works 
on Windows too, but I doubt Windows users will care to use it over Creative's 
version. For Windows, just bother Creative to fix the bug if it's still 
around. ;) You can check out OpenAL Soft here, if you're interested: 
http://kcat.strangesoft.net/openal.html


If you don't want to go that route, then I can't think of anything that will 
work correctly. Even with fudging the per-source parameters to make them 
behave as if controlled by a second listener, some parameters can't be done 
properly and the real listener may cause interference (eg. with coning).