Arch Linux

roobre

Member

From: Spain

Registered: 2010-10-10

Posts: 34

[Solved] USB audio crackling and popping, not reproducible on live USB

Hi everyone,

It's been a long time since I posted here, I hope some of you can lend me a hand because I'm at my wit's end here.

It is basically what the title says: USB audio cards on my work's laptop,  a DELL Latitude 7480, show random popping sounds when playing audio. This artifacts do not happen when nothing is playing. I have tested this with tho USB cards in two laptops, I'll organize the scenarios in bullets because otherwise it will get confusing quickly.

In all I have tested the problem with `speaker-test -t sine -f 1000`.

DELL running arch, with any kernel (-zen, -lts, -lts414):
* Popping sounds when playing audio with a USB card (2 tested), not with built-in audio
* This happens with both pulse and just alsa (pulseaudio killed and disabled)

DELL running ubuntu 18.04.4 LTS live, pulseaudio 11
* No issues with the same usb card
* Pulse config files are identical

DELL ArcoLinux live (same kernel and pulseaudio version as my installation)
* No issues with the same usb card
* Pulse config files are identical

Personal laptop (Thinkpad Yoga) running arch, -zen and -lts
* No issues with the same usb card

Things I have tried:
* Several kernels (-zen, -lts, -lts414)
* Downgrading to pulseaudio 12 (current version on arch is 13)
* `load-module module-udev-detect tsched=0`
* Changing pulse sampling rate and bit depth, in almost all combinations my DAC supports
* Using ALSA directly (by stopping pulseaudio.{service,socket} and forcing ALSA_CARD for speaker-test)

Nothing suspicious related to audio or usb shows up on dmesg or the journal.

Any hint is welcome here :(

Last edited by roobre (2020-03-13 17:38:36)

cirrus

Member

From: Glasgow Scotland

Registered: 2012-08-24

Posts: 340

Website

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

have a read here if our fine wiki was of no help
https://major.io/2019/03/04/stop-audio- … -hd-audio/

---

Ancestoral Clan https://cirrus.freevar.com/mclean.html

roobre

Member

From: Spain

Registered: 2010-10-10

Posts: 34

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

have a read here if our fine wiki was of no help
https://major.io/2019/03/04/stop-audio- … -hd-audio/

Thanks for the suggestion! However it didn't make any difference

The module that handles usb audio cards is not `snd_hda_intel` in this case, but `snd_usb_audio`. It does not have any power saving parameter, and in fact no writable parameters at all.

[root@Spinda]# ~> l /sys/module/snd_usb_audio/parameters 
total 0
drwxr-xr-x 2 root root    0 Mar 12 14:54 .
drwxr-xr-x 7 root root    0 Mar 12 11:36 ..
-r--r--r-- 1 root root 4.0K Mar 12 14:54 autoclock
-r--r--r-- 1 root root 4.0K Mar 12 14:54 device_setup
-r--r--r-- 1 root root 4.0K Mar 12 14:54 enable
-r--r--r-- 1 root root 4.0K Mar 12 14:54 id
-r--r--r-- 1 root root 4.0K Mar 12 14:54 ignore_ctl_error
-r--r--r-- 1 root root 4.0K Mar 12 14:54 index
-r--r--r-- 1 root root 4.0K Mar 12 14:54 pid
-r--r--r-- 1 root root 4.0K Mar 12 14:54 quirk_alias
-r--r--r-- 1 root root 4.0K Mar 12 14:54 skip_validation
-r--r--r-- 1 root root 4.0K Mar 12 14:54 use_vmalloc
-r--r--r-- 1 root root 4.0K Mar 12 14:54 vid

Regards,

roobre

Member

From: Spain

Registered: 2010-10-10

Posts: 34

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

After countless hours of debugging and trial and error, I identified the root cause of the issue: i8kutils kernel driver. To my shame, this is even documented in the Arch Wiki... but not in any of the audio articles.

I'll drop i8kutils and mark this as solved. Hopefully it will help future searchers.

paozaf

Member

Registered: 2012-11-29

Posts: 68

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

Hi all, hi riibre,
thank you very much for the suggestion, it fixed my problem.
In particular, I had some crackling during recording and playback via a Line6 Helix device (a guitar pedalboard that can serve also as a sound card).
I have a Dell Precision 5520 and I installed the package 8kutils-git 20170307.83622d1-3.

As said before, I fixed the recording problem by stopping the i8kmon service, at least during audio recording.
Now the question is: is it dangerous to stop this service since it controls motherboard fans?
When I run a recording session it uses a lot of resources (for a long time), so maybe an appropriate fan speed could be important.

Thank you!

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,668

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

Any system should be able to work without user/OS level fan control. Your BIOS/UEFI should always set/control safe defaults. So no it shouldn't be dangerous.

roobre

Member

From: Spain

Registered: 2010-10-10

Posts: 34

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

As V1del said, BIOS will manage your fan just nice. Perhaps it will be noisier, but it won't burn your laptop. Remember, however, to disable `dell-bios-fan-control-git` if you used it, as it would prevent the BIOS to take over the fan control even if i8kmon is disabled:

systemctl disable --now dell-bios-fan-control

Otherwise, nothing will be controlling your fan and bad things may happen.

paozaf

Member

Registered: 2012-11-29

Posts: 68

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

Thanks a lot!
No, I don't have dell-bios-fan-control-git.

So now the question is:
generally speaking, not only for audio recording, is i8kmon required?

According to this page no:
https://wiki.archlinux.org/index.php/Laptop/Dell

I installed Arch 3 years ago, so maybe now i8kmon can be no longer necessary.

Thanks again!

roobre

Member

From: Spain

Registered: 2010-10-10

Posts: 34

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

Thanks a lot!
generally speaking, not only for audio recording, is i8kmon required?

No it is not, it is only useful if you want to define custom fan curves.

paozaf

Member

Registered: 2012-11-29

Posts: 68

Re: [Solved] USB audio crackling and popping, not reproducible on live USB

Thanks!