[pulseaudio-discuss] Missing analog profiles

[Colin Guthrie]

'Twas brillig, and Spidey / Claudio at 20/06/11 14:11 did gyre and gimble:
> Yeah. I've also taken the time to learn about Pulse Audio, it's
> modules, it's configuration files. It's definitely cool. There is just
> one thing I didn't understand fully. Is it ALSA that starts the PA
> daemon?

It can do.

Basically PA is started on demand when needed by the client library. PA
clients are any application that wants to use PA (all of these
applications, so far and as thoroughly recommended, use the libpulse
client library we ship). This would include volume control apps (e.g.
pavucontrol, kmix, applets etc.) and sound output apps (e.g. rhythmbox,
amarok etc.)

Our bridging layer between applications which only speak to alsa (the
alsa-pulse plugin) also uses libpulse and thus turns any alsa
application into a pulse client too.

So by following this logic, an alsa client can launch PA if needed.


We also start PA in other ways too: Most notibly when X11 is
initialised. Normally, an autospawned PA will exit after a period of
being idle. With X11 involved we know the user is still there (even if
they've gone to make a cup of tea!), so we don't want to exit PA until
the user has logged out of X11. Therefore we also use an XDG autostart
file to start PA when X11 inits, and also load some X11 specific modules
into PA to prevent this automatic exit until X11 quits.


There is something similar done for the KDE support module that is
loaded into PA when KDE initialises.


HTHs

Col



-- 

Colin Guthrie
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http://colin.guthr.ie/

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