[SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

lefteyexl · 2011-04-10 00:05:10

Hello all,

I've been finally able to set up a working configuration for making music with my computer. I have installed Jack, with PulseAudio as a Jack client to use Skype, and configured ALSA 1.0.24. I have specified working values in my /etc/security/limits.conf in order to get rt priority.
At first I let Arch using the latest version of kernel 2.6.37. With that sound system config and kernel 2.6.37, sound is just perfect for my needs.

Then I wanted to try out kernel 2.6.38-ck-core2, just to see if there were any differences. I installed it and restarted my computer into the 2.38 kernel.

Now the trouble begins: when I use Arch with kernel 2.6.38, I can hear some distorsions, more like crackling, in audio files (MP3, FLAC, even sound from Flash...). The crackling is not always audible, I mean that it's random, but it plays during like 5 seconds, then disappears, and then plays again... And this happens in any audio stream.

At first I thought that maybe Jack was having some issues. So I deactivated it, which implied I also deactivated its client, PulseAudio. And I routed everything directly to ALSA.
But I was still having that distorted, crackling sound...

So... I'm wondering if anyone here has experienced this problem. I'm suspecting the ALSA modules in kernel 2.6.38-ck-core2.
I'll try to test more with kernel-2.6.38-ck and keep you informed if I find somehting.

Thanks )
Chris

Last edited by lefteyexl (2011-04-11 09:43:14)

graysky · 2011-04-10 00:38:11

I'm running that kernel on my box and no problems...?

Fackamato · 2011-04-10 13:10:04

Try disabling power saving features of the sound modules, if any of them has got it?

lefteyexl · 2011-04-10 13:40:16

@Fackamato

Thanks, I'm going to try this now. I don't really know if it's activated but anyway I've added the following line to /etc/modprobe.d/modprobe.conf (as the ALSA wiki suggests):

options snd-usb-audio power_save=0

I'll keep you all informed.
Thanks!

Chris

Last edited by lefteyexl (2011-04-10 13:43:41)

lefteyexl · 2011-04-10 15:09:23

Well, no luck with "options snd-usb-audio power_save=0"... When I play sounds using Arch 2.6.38-ck-core2, I can hear some crackling every now and then. What I mean by crackling is some pops and clicks.
When I lower the volume with alsamixer, the crackling goes on, at a lower level though. It does not disappear at all. I'm not playing sounds too loud, so I'm pretty sure that this is not due to sound saturation.

Ah, something I think is important: I've been able to reproduce the issue with generic kernel 2.6.38 in Ubuntu.

I'm sorry I don't really know what else I can say... Do you need my config files? If so, which ones do you need?
Thanks a lot, the truth is I'm a bit puzzled with that issue |

Last edited by lefteyexl (2011-04-10 15:14:22)

graysky · 2011-04-10 15:11:42

Is this hardware related rather than kernel related? Under what situations does the problem not exist?

lefteyexl · 2011-04-10 15:19:29

@graysky

The problem does not exist if I use Arch with kernel 2.6.37.5-1, using the same sound system configuration (ALSA 1.0.24 - Jack2 with PulseAudio as a client).
I have also been able to check under Windows 7, and I have no such problem.

lefteyexl · 2011-04-10 23:23:48

Hey all,
First I'd like to apologize: the problem is solved and was not related either to kernel 2.6.38-ck or ALSA 1.0.24. I spent hours suspecting ALSA while I shouldn't have been so determined.
In fact, it was all about my Jack config and the way I configured it to be "system-wide". I didn't realize it af first, but the latency I set was much too high (frame/period: 512). Moreover, it seems that even when I stopped qjackctl the jackd daemon was still running, due to the "system-wide" mode.

Since I lowered the latency (frame/period: 64), I have not heard any pop or crackling while running Arch with kernel 2.6.38-ck-core2. But I still don't understand why I didn't experience that problem with generic kernel 2.6.37, even with frame/period set at 512...

Anyway, this issue is solved. It was my mistake.
Chris

Last edited by lefteyexl (2011-04-10 23:30:05)

graysky · 2011-04-10 23:28:47

@op - np, glad you got it solved. I'm glad my packages are okay

lefteyexl · 2011-04-10 23:36:11

@graysky: yeh, sorry about that... Well, i was more inclined to think it was a generic 2.6.38's problem, as it happened in Ubuntu... But as I set up the exact same config in Ubuntu, it is now solved too!
Anyway, is it possible that a higher latency in Jack would not affect the same way while using the Arch 2.6.37 stock kernel? This would explain everything...

Thanks a lot for all your replies
Cheers

Chris

Arch Linux

#1 2011-04-10 00:05:10

[SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#2 2011-04-10 00:38:11

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#3 2011-04-10 13:10:04

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#4 2011-04-10 13:40:16

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#5 2011-04-10 15:09:23

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#6 2011-04-10 15:11:42

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#7 2011-04-10 15:19:29

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#8 2011-04-10 23:23:48

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#9 2011-04-10 23:28:47

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

#10 2011-04-10 23:36:11

Re: [SOLVED] Kernel 2.6.38-ck-core2+M-Audio Mobile Pre USB–Sound crackling

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