[Openal] Openal, S/PDIF and surround [Almost SOLVED]

[Alfredo Pironti]

On Thu, May 22, 2008 at 10:23 AM, Chris Robinson <chris.kcat at gmail.com> wrote:
> On Thursday 22 May 2008 12:24:57 am Alfredo Pironti wrote:
>> - After playing a bit in tremulous, when there were many sound being
>> produced at the same moment, audio started clipping very noisely, and I
>> could see on my audio receiver that s/pdif signal was being sent
>> intermittently. I don't know if it's game or OpenAL fault. If it's
>> OpenAL fault, maybe switching to OpenAL Soft can do the trick.
>
> Just as an FYI, this *is* one of the issues the old (v0.0.8) OpenAL has, that
> OpenAL Soft "fixed" (it's actually because of the amount of processing OpenAL
> did would cause delays in getting the data out to the card.. OpenAL Soft's
> cleaner code doesn't have this happen as easilly, but it still theoretically
> could under heavy loads; I'm sure the added a52 encoding doesn't help
> matters ;)).

OK, I'm definitely going to switch to OpenAL Soft. Thanks again for the hint.

>
> Odd about the stereo lockout after using the plugin, though. Only reason I
> could think of for that is a bug in the plugin itself, or the app's not
> closing openal properly for it to close the device (though alsa usually
> releases it on its own when the process dies).

I still don't clearly understand routing of signals within alsa, but I
think that in my
configuration something like this happens: when my music player
is in playback, PCM output is sent to the default hardware
(analogic?), and it is also routed over s/pdif, by enabling the
appropriate switch
in the alsa mixer. However, when I use passthroughs (eg for DVD
movies), I suppose direct access to s/pdif
is granted to the application (I cannot mix sources, indeed, this is
what pulse audio should be for).
So, probably a52 is taking direct control over s/pdif (like
passthroughs), and this is released only when I explictly
access s/pdif by the "speaker-test" application. My music player does
not behave like
"speaker-test" because it is not configured to explicitly go through
s/pdif. Probably I should set
that my default device is s/pdif. I'll try this as soon as I'll be
back home, and let you know.

Chris, I sincerely want thank you very much for your great support ;-)

Cheers,
Alfredo