[tlug] How to change IRQ address for a sound card?

[Dave M G <dave@example.com>]

TLUG,

(Please ignore any other duplicate or posts similar to this one. Had an 
accident with my email.)

Earlier today I had posted a question on the Skype forums asking about 
some trouble I was having with Skype audio. When Skype plays back any 
sound at all, whether it's an incoming call or even when it plays one of 
it's local .WAV ringing or event sounds, it pops and stutters.

I was totally convinced the problem was localized to Skype. When I play 
MP3 files in Amarok or XMMS, they play smooth as can be. When I play 
video files with Xine or Totem, there are no sound troubles. When I play 
Flash movies in FireFox, they seem fine.

And then, a little earlier, I opened up an MP3 file in Audacity. And it 
had the exact same popping and stuttering problem that Skype has. I 
checked other MP3 files, I played them on a different machine, I played 
them in different applications.

The short story is that the problem I thought was only in Skype is 
definitely in Audacity as well.

The only common factor to both of these applications that I can think of 
is that they both handle recording as well as playback, in their own ways.

However, one web page about Audacity said playback may be stuttered if 
the sound card is sharing an IRQ with something else.

This command seems to indicate that my sound card, an HDA Intel on my 
motherboard, is sharing IRQ 20 with a USB device:

$ cat /proc/interrupts
 CPU0      
 0:     223428   IO-APIC-edge      timer
 1:        439   IO-APIC-edge      i8042
 7:          0   IO-APIC-edge      parport0
 8:          3   IO-APIC-edge      rtc
 9:          1   IO-APIC-fasteoi   acpi
12:          4   IO-APIC-edge      i8042
14:      15078   IO-APIC-edge      libata
15:          0   IO-APIC-edge      libata
16:      41915   IO-APIC-fasteoi   nvidia
17:     196853   IO-APIC-fasteoi   uhci_hcd:usb2, libata, eth0
18:      15565   IO-APIC-fasteoi   uhci_hcd:usb1, ehci_hcd:usb5
19:          0   IO-APIC-fasteoi   uhci_hcd:usb3
20:        800   IO-APIC-fasteoi   uhci_hcd:usb4, HDA Intel
NMI:          0
LOC:     223308
ERR:          0
MIS:          0

I'm only vaguely aware of IRQs from my Windows days, and only understand 
that they are numbers assigned to hardware. But this is my only lead in 
my sound problem, so I'd like to try changing the IRQ settings if I can 
to see if it makes a difference.

The web site suggested I download something called "irqtune", which I 
did, but also warned that changing IRQs is something that should only be 
attempted if one is sure of what they are doing because it can cause 
terrible consequences if done wrong.

Lastly, the web site said audio devices "prefer" to be on IRQ 9, 10, or 
11. I have 10 and 11 open, so...

How can I safely get my HDA Intel audio device to be on IRG 10 or 11?

Any advice would be much appreciated.

--
Dave M G
http://www.tlug.jp/wiki/User:Dave_M_G