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Old 07-01-2007, 05:27 PM   #1
LQ Newbie
Registered: Feb 2004
Location: Brisbane, QLD, Australia
Distribution: Debian
Posts: 29

Rep: Reputation: 15
choppy spidif output (maybe due to hard drive access)


I recently got myself a 5.1 amp+speakers and am finding that spdif audio (digital through coax) cuts out every so often. By this I mean I hear a click, silence, and then sound again. The same sound when I switch between 5.1 and pcm.

I think this might be related to my hard drives as this seems to happen more often when downloading with azureus and more often when playing 5.1 audio (5.1 videos cutout every few minutes). If I'm not downloading and I'm playing a stereo ac3 file it is fine as far as I can tell.

Anyone have any idea what could be causing this?

I'm thinking some interference between the hard drives and the spdif out but have no idea how to further diagnose. I read somewhere that acapi can cause problems with certain ac97 audio controllers but I disabled all power management in my bios and still no luck.

I'm runing ubuntu fiesty latest patches on an amd64 and a k8v motherboard, which has a via chipset. This happens in both xine (configured to use pass through) and mplayer (with the config option afm=hwac3)

My surround system is a philips htr 5000, I connected a dvd player with toslink optical to it and it works perfect with 5.1 so I think there is nothing wrong with its decoder. I also tried another coax cable (a short gold plated thick one) and still get cutouts.

Old 07-02-2007, 06:44 AM   #2
Registered: Apr 2005
Location: chained to my console.
Distribution: LFS 6.1
Posts: 143

Rep: Reputation: 18
hey there....

try the program "top", run it from a console.

a breif explanation of some of the numbers in top....... each of these lines is from the top program, you can use them to understand your top display.

1st line
top - 12:19:42 up 13 days,  9:10,  1 user,  load average: 0.10, 0.17, 0.17
this shows you the uptime (how long your pc has been turned on), how many users are logged in and the 'load average'. the load average is basicly, how many programs are sitting in the queue waiting for the processor. if the load average numbers are high, that means you have lots of programs fighting over the processor.

2nd line
Tasks: 134 total,   3 running, 131 sleeping,   0 stopped,   0 zombie
this is how many tasks (programs) top can see running. its ok to have a high number of tasks, i have 134 running just to show my desktop. only start to worry if you see zombies. a zombie is a lost or crashed program that needs to be killed.

3rd line
Cpu(s): 16.6%us,  1.7%sy,  0.0%ni, 79.7%id,  1.7%wa,  0.0%hi,  0.3%si,  0.0%st
this line tells you about your cpu (there may be more of these lines if you have more than one cpu). the first "us" number is how much of the processor *you* are using. the "ni" number is how much of the processor nice'd programs are using and the "id" number is how much of the prcessor is idle. an important number for you is the "wa" and "si" numbers, if these are high it means the system is spending a lot of time waiting for the hard drive, etc. whilst the system is waiting on the hard drive, it struggles prcessing anything else. this is the line to look at to see if your hard-drive access is using up all of your processor.

4th and 5th lines
Mem:   1035772k total,  1022124k used,    13648k free,    24716k buffers
Swap:  1646620k total,   310784k used,  1335836k free,   753888k cached
these lines show how much ram you have and how it is being used. even though the system may show a small number for "free", you can assume that the "buffers" and "cached" numbers are free ram too. he buffers and cached numbers show how much ram your system is using to cache data from your hard-drive, usually this is pretty much all of your free ram, but dont worry if linux tells you it is using all of your ram, it will release its cache if any of your programs ask for the ram back. on my line it shows i have 1035megs total, 1022 megs used and 13 megs free, but i am using 735megs for disk cache, so if i need it, linux can release the 735megs of cache for my programs to use.

the rest of the lines.......
 5378 root      15   0  122m  28m 2688 S  7.6  2.8 239:23.16 Xorg
 5546 zidane    15   0 58892  14m  10m S  1.7  1.4 169:31.49 kicker
 7783 zidane    15   0 65196  46m  20m R  1.7  4.6   0:52.05 konqueror
now, this is the really cool part. the rest of the screen shows you the top few programs running (see, hence the name top). if you look at the top of the list, you will see the programs using the most cpu (top sorts by cpu by default). on my lines, it shows Xorg is using the most processor (2.8% of my processor is being used by xorg). so, say you are running azuerus, if you see it in top using 99% cpu, and top is showing 99% wa on your processor line, then you can tell that azuerus is using all of your processor waiting on the hard-drive.

the top output is pretty complex, and shows a lot of information, but it really is your best tool in telling just what is going on inside your machine right now. let it run in a console and watch it for a few minutes, see how it changes when you do things, you will pick up what means what very quickly, and if all else fails, you can always check the man page the important thing to remember is that you dont need to understand every single number, you just need to be able to get an idea of which program is at the top of the list hammering your system.

i tend to leave top open in a console on my desktop all the time. i just like to see whats going on and if my machine is sluggish, what is causing it.

on a side note, if you are using azuerus for torrents, and it is hammering your system (i dont use it myself), try using a lighter client. personally i use a program called "rtorrent". its simple, reliable, fast and light on the system.
Old 07-02-2007, 01:16 PM   #3
LQ Newbie
Registered: Feb 2004
Location: Brisbane, QLD, Australia
Distribution: Debian
Posts: 29

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Thanks for your advice. It doesn't look like anything is over the top when it comes to usage. I tried closing all my processes and still get problems although maybe not so often. It's hard to test this sort of thing.

I usually have quite a lot running but I have a amd64 3000 with 1GB of ram so it should be able to take it.

Here is the top of my top with a loaded system. ie. xine playing a 5.1 decent res mkv file with my usual programs running - java is azureus. xine and xorg both take turns to be #1, but both stay under 20%. If I sort by memory firefox is usually #1

top - 18:48:56 up 23:29,  1 user,  load average: 1.35, 1.19, 0.61
Tasks: 117 total,   1 running, 115 sleeping,   0 stopped,   1 zombie
Cpu(s): 23.8%us,  3.6%sy,  0.0%ni, 61.9%id,  6.6%wa,  2.6%hi,  1.3%si,  0.0%st
Mem:   1027348k total,  1017720k used,     9628k free,     3436k buffers
Swap:  1060280k total,    39164k used,  1021116k free,   474112k cached

10339 i         15   0  399m  44m  13m S 15.6  4.5   1:16.37 xine
 5671 root      15   0  139m  67m  17m S  4.3  6.8   5:41.44 Xorg
 9620 i         15   0  146m  22m  17m S  3.7  2.3   0:02.07 konsole
10495 i         18   0  677m 123m  19m S  3.7 12.3   0:29.80 java
 6639 i         15   0  136m 2796 1480 S  1.3  0.3   0:06.90 gnome-screensav
10320 i         15   0 44236 7412 5456 S  0.3  0.7   0:00.60 npviewer.bin
    1 root      18   0  5068 1960  564 S  0.0  0.2   0:00.72 init

I also get firefox, metacity, konqueror, kuake, top and the occasional other app in the top five, but none of their cpu is ever shown above 5%.

ps axf shows me that the zombie is netstat, which firefox started for some reason
12033 ?        Sl     2:27 /usr/lib/firefox/firefox-bin
12043 ?        Z      0:00  \_ [netstat] <defunct>

Last edited by spacedoubtman; 07-02-2007 at 01:17 PM.
Old 07-02-2007, 01:53 PM   #4
Registered: Apr 2005
Location: chained to my console.
Distribution: LFS 6.1
Posts: 143

Rep: Reputation: 18
hmmmmm, now that top output looks pretty fine, nothing is hammering your system in particular, and the behaviour of xine and xorg is very similar to my own systems response (i also use 5.1 audio over an spdif, but mine is over a soundblaster card).

out of curiosity, what is youe dmesg output? anything in there about dropped frames or errors from any of the drivers? (you might also want to check the various logs in /var/logs to see if any of the programs themselves are complaining).
Old 07-11-2007, 08:27 AM   #5
Registered: Feb 2003
Location: Germany / Schwetzingen
Distribution: (K)ubuntu, Debian seldom SuSE
Posts: 76

Rep: Reputation: 15
A note on the zombie issue

Dear all,

The netstat zombie-process due to firefox is often documented.
A workaround is to start firefox with these parameters "firefox --sync -browser -a %u"
Some report that the -browser is not necessary others do state it is.
Try it. In my case it seems to not recquired (Ubuntu Feisty)
Old 02-03-2008, 11:50 PM   #6
Registered: Jun 2007
Distribution: Debian
Posts: 73

Rep: Reputation: 16
Thumbs down Try everything that's obviously wrong.

I have been wondering for months what is wrong with AC97 on-board digital sound. It turns out all I needed to do was turn OFF IEC958 in "Volume Control" [alsamixer was worthless!] to get digital coax to work on Asus p5p800. Bizarre, but nothing else works. What crap??


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