Thursday, October 29, 2009

Caveats for audio in 9.10

Here follows an update for 9.10 to this month's earlier caveats:

If you use Ubuntu:
  • Use Karmic's kernel, not Jaunty's. A lot of you with Realtek and IDT/Sigmatel HDA codecs are being bitten by /boot/grub/grub.cfg not being updated properly, resulting in Jaunty's 2.6.28 kernel being used instead of Karmic's 2.6.31. Jaunty's kernel has pretty subpar performance for PulseAudio, and you should not incorrectly blame PulseAudio.
  • Check that slmodemd is not running if you're seeing a dummy/null sink in the volume control applet. Arguably PulseAudio's module-udev-detect should allow the device instead of bailing when detecting it, and an approach is under discussion for future versions. In the meantime, you can either instead load module-detect in /etc/pulse/ (or ~/.pulse/ or kill slmodemd.
  • Install linux-backports-modules-alsa-karmic (then reboot) if you have a very new computer, because that package enables audio on quite a few very new laptop models and contains much improved support for microphone auto-switching.
  • Use a temporary alternate channel mapping for PulseAudio if you have an ice17xx-based sound card. Please be aware that the fault lies with alsa-lib not PulseAudio and will be addressed in 10.04 LTS.
  • Configure PulseAudio to ignore your sound driver's misreported dB information if you experience "overdriven" sound.
  • Attach a verbose PulseAudio runtime log to your PulseAudio bug report.
  • Attach an ALSA codec dump to your linux bug report if jack sense (e.g., connecting headphones mutes internal laptop speakers) does not seem to function properly.
As always, thank you for helping improve Ubuntu!


  1. What's the deal with using Pulse in Kubuntu? It doesn't seem to be installed by default, yet in the Multimedia System Settings, one of the devices listed is pulse. I seem to get the "one device is blocking another from the soundcard" thing pretty often, so if Ubuntu's set Pulse up better now, I'd love to use it.

    Thanks for all your work on getting a better sound server onto the free desktop.


  2. Thanks for this useful summary.

    Regarding this page:

    Is the information automatically attached by ubuntu-bug not sufficient for your purposes? If not, please let me know what's missing so that we can get it fixed up.

    Users shouldn't need to collect and attach this data manually when we can do it for them automatically.

    Similarly, should we turn up the default verbosity for pulseaudio and attach that automatically as well? Or if it's too verbose, perhaps create an interactive apport hook?

    Is there a known bug with grub.cfg not getting updated?

  3. Hey Matt,
    here's a bug for grub.cfg:

    But upgraders would still have GRUB1, right? So for them it's menu.lst hat's not being updated. I've just been telling people to run "sudo update-grub"

  4. Following the use Karmic kernel tip I have edited the grub file and now have sound after my upgrade - but now my desktop has gone blank, as does Firefox if maximised - you win one and lose one.

  5. How to do this?: "Configure PulseAudio to ignore your sound driver's misreported dB information"

    Can someone tell me how to do this i'm begginer and dunno what i need to edit and what to write

  6. Use Karmic's kernel, not Jaunty's. A lot of you with Realtek and IDT/Sigmatel HDA codecs are being bitten by /boot/grub/grub.cfg not being updated properly, resulting in Jaunty's 2.6.28 kernel being used instead of Karmic's 2.6.31. Jaunty's kernel has pretty subpar performance for PulseAudio, and you should not incorrectly blame PulseAudio.

    sudo update-grub

    This did the trick for me.

  7. Im using Karmic... i had this problem before on 8.10 and i can't remember how i solved it.

  8. forgot to mention that i first removed the menu.lst file.

  9. How do you remove menu.lst file with the terminal?

  10. 9.1 is a train wreck unless you are a systems programmer... stay with 9.04 if you still want the ability to tweak your mic audio.

    Also if you are using dual boot with the dvd of 9.04 2.6-11 for evaluation and install do not upgrade unless you wish to loose the windows MBR !!

  11. Mic audio is a known regression in 9.10 for some HDA codecs -- Realtek 26x, mainly -- due to *linux* not *pulseaudio*. That's the sole reason the linux-backports-modules-alsa-karmic-generic package (which pulls in linux-backports-modules-alsa-$(uname -r)) exists.

  12. "Use Karmic's kernel, not Jaunty's. [....]"

    I've only been using Ubuntu (any Linux, period) for less than two months, and have no idea how to use one kernel over the other. Can someone please explain this in "stupid" terms? (lol)

    "sudo update-grub"

    I ran this when I first upgraded to 9.10, and it was successful for about two to three days. Then my audio went out again, and running this command in the terminal now does nothing.

    This has been going on for a month now, and I can't find a solution. Being new to Ubuntu, I also am new to finding where to go to obtain help and solutions. I'd appreciate any help available, including links to sites/pages other than Ubuntu Forums and Launchpad (as, obviously, I've already found these).

    Thank you in advance!

  13. Hi!: linux-backports-modules-alsa-karmic it's working for mi. Thanks.

  14. this works great for me, but i am going to check out that alsa jack link. its the only thing it doesnt fix


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