Bug 156592

I can confirm the "crackling" problem with an M-Audio Audiophile 2496 soundcard.
I'm not 100% sure when the problem started but I think the last kernel that
worked properly was 1251.

I can confirm both of these symptoms.  I encountered crackling as well as the
arts issue.  First encountered after updating:

alsa-lib-1.0.9rc2-1
-------------------
* Fri Apr 22 2005 Martin Stransky <stransky> 1.0.9rc2-1
- updated to 1.0.9rc2
- add ainit tool - dmix is now default pcm device 

using:

/proc/asound/cards
0 [SB0400         ]: Audigy2 - Audigy 2 Value [SB0400]
                    Audigy 2 Value [SB0400] (rev.0, serial:0x10011102) at xe800,
irq 5

/proc/asound/modules
0 snd_emu10k 

I got the crackling sound-- but only on things that use esd, and on the
proprietary flash plugin.

Testing with gstreamer-properties shows that esdsink produces the crackling
sound, but alsasink and osssink don't seem to.  (Not running KDE, so I can't
test aRTs.)

Using an SBLive.

Some of these could be fixed by alsa 1.0.9rc3, as this bug says:
https://bugtrack.alsa-project.org/alsa-bug/view.php?id=1082

Please update alsa from rc2 to rc3 in development.

Here is the testing version of 1.0.9rc3 for FC4

http://people.redhat.com/stransky/alsa-lib/

I have the same problem with 1.0.9rc3 and today's kernel. 
 
I briefly got the sound working but then it became silent. I could still use mplayer 
and realplayer to listen to things but nothing from KDE. 
 
Furthermore knotify crashes upon logout thus hanging the logout process.  
Other things seem to crash as well. 
 
KDE is not usable with these combinations 

PS: Kernel is still at 1.0.9rc2. 

So my other problem, with the flash plugin, is also resolved if I kill esd and
restart the browser.  So apparently dmix or this version of alsa interacts
poorly with esound and aRts.  I'll try 1.0.9rc3 at some point; for now I'm just
not using esd since I don't really need it.

This is probably bad for people who need sound over network connections, though.

Installing alsa-lib-1.0.9rc3 fixed the crackling for me (running
kernel-2.6.11-1.1275_FC4).

I solved my problem with KDE using alsa-lib-1.0.9rc3 and 2.6.11-1.1282 kernel.   
Essentially it seems like arts is discontinued in KDE. In KDE 4.0 they will have   
something else like gstreamer etc. The problem with alsa had been reported   
there too with no solution yet. The best way to deal with this I think is to turn off   
arts altogether.   
   
So, I go to control center, choose sounds --> sound system and there choose   
"no audio input/output" option. Also, in the first page uncheck "enable sound   
system" buttion. This will make arts not start next time (it hanged my KDE when   
I chose that so I did a ctrl-alt-backspace and logged back in.)   
   
After that, again in control center --> sounds, go to system notifications page and   
at the bottom choose the "Player Settings". Uncheck  "use KDE sound system"  
and check  "use an external player" and choose /usr/bin/play as the player (from sox). 
save and restart. All KDE sounds are working fine for me after doing this. If someone 
has a better choice for player I would be interested to hear it. 

1.0.9rc3 fixes alsa problems for me, dmix works by default. Even
gstreamer-properties works now.
I haven't tried esd, there's no need for it now (unless using sound
over network...)

1.0.9rc3 also seems to have resolved the issue(s) for me.

rc3 has fixed aRts for me to a certain extent -- it no longer seems to take over
the CPU like it used to, certainly. However, it didn't seem to autosuspend
properly; I hadn't played any sounds for ages, but aRts was still active, and
"artsshell suspend" and "artsshell terminate" appeared to hang.

Unfortuantely, I was wrong about it being resolved.  However it may be
a new(?) bug.  All KDE sounds stop working after a short period of
time.  None of the sounds work in any form.  (Yet XMMS will work) 
Gaim using Command aplay stops working as well.  This occurs also when
using Arts.

However, I experience none of this while using Gnome.  All Gnome
sounds have been functioning for a couple of hours now without fail. 
KDE sounds fail with 10-15 minutes.  I reverted back (as suggested in
fedora-test) from 1.0.9rc3 to 1.0.9rc2-4

If you still have problems with aRts, disable dmix in
/etc/asound/ainit.conf (default in 1.0.9rc2-4). 

I'll improve config/behavior of sound cards in FC, but it will take
more time and it heads into FC5.

Regarding to a troubles with dmix, it's known issue, upstream works on
it. You can find more info on alsa-devel list.

What is the correct way to disable dmix in ainit.conf

You can disable dmix and dsnoop by writting these lines 
to /etc/asound.conf:

pcm.!default { 
  type hw 
  card 0 
}

ctl.!default { 
  type hw 
  card 0 
}

where 0 is number of the card. (0 for the first one)

Comment #18 fixed my crackling sound problem on Gnome-CD. Many thanks.

Still no sound on Kscd ...