[linux-audio-user] Multiple outputs at the same time

[Robert Jonsson]

fredagen den 25 juli 2003 19.07 skrev Daniel Klein:
> Hello,
>
> again, excuse the very basic nature of my question, I should have found
> these answers myself, but I tried long and just couldn't. Maybe the
> internet as such dislikes me.
>
> I want to do something very basic. Basically that is let multiple programs
> talk to my soundcard at the same time. Simple example: XMMS is playing a
> song, someone on IRC uses a keyword to page me, my XChat perl script calls
> some form of command line mp3/wav playback program and plays a sound that
> gets my attention. Or XMMS is playing and I access a webpage with a Flash
> animation. Or the aforementioned paging situation happens while watching a
> movie with mplayer. Currently, none of those are possible to me. I must say
> I am very ignorant in this area still, am really willing to educate myself
> but find myself unable to find anything BASIC on this. A little FAQ on
> basic terminology would be grand already. What do you call things like
> ALSA, Esound and what not? How does stuff like KDE's aRts fit in?
>
> Anyway, I am running ALSA 0.5. I have tried to upgrade to an ALSA 0.9x
> once, but I remember faintly there were serious problems, so I tried to
> circumvent that upgrade for the time being. Will an ALSA 0.9x version offer
> me this functionality of multiple sound sources at the same time? I used
> esound once too, while I'm absolutely foggy as to how that worked. I
> installed it, told XMMS to talk to esound and then used a play utility that
> came along with esound. That's how I solved the XMMS is playing + notify
> sound from XChat should play situation. But esound seems to have the
> latency of a really tired old man, and that looked plain retarded with the
> little visualization window of XMMS. I know I know, not the end of the
> world, but other programs also didn't like to talk to esound (including
> mplayer). Will I need to upgrade to ALSA 0.9 then? Is that the standard
> right now? What other options do I have?

This - multiple sounds at the same time - is in linux generally handled by a 
sound server. Arts (and esound) is such an application it will fit your bill 
if the apps you wish to use are able to utilize it.
(there are commandline tools e.g. artsplay that can help you play sounds from 
apps that don't know of arts directly)
>> sound servers are though in general rather high latency.

There are other ways to solve this also, many newer soundcards support playing 
several streams directly on the soundcard. (e.g SB-Live, (not so new...))

For the cards that don't have this and if you can't use a soundserver there 
_are_ another possiblity, that is alsa. There is supposed to be a new device 
type defined in Alsa that provides this capability, whether it is finished, I 
have no idea.

ALSA 0.9 is anyway a definitive must-upgrade.

>
> Again, if you can just point me to a general FAQ about all this, please by
> any means do so.

Wish I could ;), there is a sound HOWTO somewhere, but I wonder if it's not 
getting very old and of the mark by now...

Regards,
Robert