enabling multiple apps to access the sound card simultaneously

[Michael Wardle]

Hi All

After upgrading to Fedora 2 Test 3 from Fedora 1, my sound output is
somewhat choppy and distorted, but my biggest problem is that sound is
not being multiplexed properly, so only one application can
simultanously use the sound card.

I typically run applications such as Rhythmbox and Gaim under the GNOME
Desktop.  When Rhythmbox finishes playing a song, many queued Gaim
sounds are spewed out at once.  Rhythmbox then fails to reopen the sound
card to play the next song in the playlist.  Other applications that
will play sound but only when they have exclusive access include Totem
and aplay.  When I attempt to test GNOME event sounds (which I
ordinarily have disabled) in the GNOME Sound Preferences control panel,
I hear no sound.

Gaim is configured to use the Automatic detection method (however I've
tried both ESD and Command: "aplay %s" methods), GStreamer is configured
to use the ALSA output sink.  GNOME is configured to start the sound
server (esd) at start up.  GNOME Volume Control shows two pages, the
first titled "Realtek ALC650 rev 3 [Audio Mixer (OSS)]", the second
titled "NVidia nForce2 [Alsa Mixer]".

I am using an nForce 2 mainboard with an nVidia nForce 2 APU/Realtek ALC
650 which uses the Intel 8x0 ALSA driver.  The relevant channels appear
to have a moderate volume after having to manually set them
(particularly PCM is unmuted).

>From time to time, I see the following message in syslog, despite only
having only one sound card (the onboard nForce 2), which I believe means
I should only have sound-slot-0 and snd-card-0.  The timing does not
appear to coincide with occasions where multiple applications are
attempting simultaneous access, but I'm not entirely sure:
modprobe: FATAL: Error running install command for sound_slot_1 

To me this is a big problem, and I'd like to file it as a bug report,
but I need to verify there is not a problem with my configuration and
solicit some tips first.  I've also experienced some of the other
sound-related problems mentioned elsewhere on this list (including PCM
being muted by default), but I believe this is a different problem.  Any
ideas appreciated.

Other possibly relevant details:
> cat /proc/asound/cards
0 [nForce2        ]: NFORCE - NVidia nForce2
                     NVidia nForce2 at 0xe2080000, irq 5

> grep snd /etc/modprobe.conf.dist
alias char-major-116-* snd
alias sound-service-*-0 snd-mixer-oss
alias sound-service-*-1 snd-seq-oss
alias sound-service-*-3 snd-pcm-oss
alias sound-service-*-8 snd-seq-oss
alias sound-service-*-12 snd-pcm-oss
install sound-slot-* /sbin/modprobe
snd-card-${MODPROBE_MODULE##sound[_-]slot[_-]}

> grep snd /etc/modprobe.conf
alias snd_card_0 snd_intel8x0
options snd-intel8x0 mpu_port=0x330

-- 
Mike