Re: [Plib-users] Onboard Sound Support?

[Steve B. <sjb...@ai...>]

Curtis L. Olson wrote:
> 
> Yeah, that sounds pretty tempting.  I haven't taken a look at OpenAL
> at all yet, but I have a project here where I need to generate two
> distinct audio streams from a single application (either to the
> left/right stereo channels or to two separate sound cards, or two apps
> to two sound cards, or something ...)

Dunno if OpenAL supports two sound cards - and you might get significant
cross-talk if you try to generate two utterly unique sounds streams
using stereo on a single card.

For SL to be able to drive two cards, you'd have to create two
instances of slDSP - each driving a different /dev/dsp. That's
possible in theory but I've never heard of anyone trying it.

Since only the very lowest levels of SL support stereo (slDSP only),
I don't think SL would help you much with trying out a stereo
solution with one sound card.

OpenAL would probably make life very difficult too. OpenAL is not
a stereo system from the point of view of the API. It's a 3D sound
system that lets you position sound sources in 3D space - it figures
out how best to play those sounds on however many physical channels
you have.  Placing one sound source off to each side of the listener
won't necessarily produce a clean separation of the audio in stereo
space.

Depending on how much manipulation of these sound streams you need
in realtime, I think you'd be better off coding down at the OSS level.
Of course if you need portability (eg to Windoze platforms) then that's
no good either.

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