[kde-freebsd] KSayit questions... .

[Michael Nottebrock]

Bartosz Fabianowski schrieb:
>> I still don't understand how arts, oss, and esd work together.
>>     
>
> It's pretty simple really. Traditionally, OSS encapsulates the sound 
> driver and provides access to the sound card through the /dev/dsp 
> device. Unfortunately, this device can be opened for writing only by a 
> single process at a time. As multimedia became more prevalent, people 
> wanted to be able to play multiple sounds at once, say to listen to an 
> MP3 but also get system notifications via jingles. The way this was 
> solved was through a sound server - a daemon that opens /dev/dsp and 
> then multiplexes whatever audio other processes send to it. KDE adopted 
> the aRts daemon, GNOME chose ESD. So, now, you have two competing 
> daemons, each of which is able to multiplex sound sources but also needs 
> exclusive access to /dev/dsp to do its work. Needless to say, this is 
> bound to fail - only artsd or esd can open the device at any given time. 
> To solve this dilemma, you enable vchans - a multiplexing facility in 
> the FreeBSD kernel that presents several "virtual" sound cards as 
> numbered /dev/dspX devices. artsd can then connect to one of those, esd 
> to another and FreeBSD takes care of multiplexing their outputs into one 
> stream that is fed to the actual sound card.
>   
I'm impressed how you are able to summarize all this without the
slightest bit of a sneer. :)

For completeness sake I'd like to mention though that it is also
possible to configure aRts to use ESD, if the arts port has been
compiled with the ESD option turned on. This way aRts can be run in
GNOME without requiring additional vchans (in addition to ESD, arts also
supports Jack and NAS for output, PulseAudio can be used as output for
arts with PulseAudio's ESD-emulation).

Cheers,
-- 

   ,_,   | Michael Nottebrock               | lofi at freebsd.org
 (/^ ^\) | FreeBSD - The Power to Serve     | http://www.freebsd.org
   \u/   | K Desktop Environment on FreeBSD | http://freebsd.kde.org


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