Adjusting volume gives uneven response

[Hugh Warrington]

I am listening to music using Rhythmbox. To adjust the volume I use the vol -/+ keys built in to my Microsoft Natural 4000 keyboard. This arrangement worked fine in 9.10. A pop-up OSD in the top-right of the screen appeared whenever I changed the volume. The full range of this indicator (from empty to full) correctly corresponded to the full range of silence to maximum volume output over my headphones.

Since upgrading to 10.04, the control behaves as follows. At the lowest setting, I get no sound output, as expected. With one press of the vol+ key, the bar becomes one notch full (I note there appear to be 18 discrete values that the OSD can indicate). However, the sound output is fairly loud: around half of the maximum output. After two presses of the vol+ key, the bar is only about 10% full, but the sound output is at or near the maximum (uncomfortably loud through my headphones). Successive presses of vol+ continue to raise the indicated volume, but have no discernible effect on the output volume.

I can watch what's going on in alsamixer while I press the vol -/+ keys. (side note: alsamixer says 'Card: HDA ATI SB' and 'Chip: VIA VT1708S'). At volume zero, the bars marked Master Front, PCM and Front are all on zero, and are marked as muted. On volume notch one (after one press of vol+), those channels are marked as unmuted, and have respective values 0, 98, 60. After two presses 0, 98, 88. After three presses 6, 98, 100. Successive presses just increase the Master Front value.

If I manually scale the PCM and Front columns using the arrow keys, I get the expected response. i.e. perceived volume output is proportional to the product of PCM and Front.

I'm using a Dell Inspiron 546. uname -a gives:

Linux alma 2.6.31-17-generic #54-Ubuntu SMP Thu Dec 10 17:01:44 UTC 2009 x86_64 GNU/Linux

The bits of lspci that I think are relevant:

00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA)
01:05.1 Audio device: ATI Technologies Inc RS780 Azalia controller

Expected behaviour: output volume scales linearly with the scale displayed on screen.

[fk (kamisli)]

I have the exact same problem. It's very annoying.
Using Ubuntu 10.04 on an Asrock 780G motherboard with VIA VT1708S onboard sound.

[fk (kamisli)]

And, the workarounds suggested at https://wiki.ubuntu.com/DebuggingSoundProblems/KarmicCaveats#Volume range anomalies don't work.

[Hugh Warrington (x-launchpad-hughw-org)]

fk, thanks a lot for that link. I've discovered something useful on a page linked to from the Ubuntu wiki (see http://pulseaudio.org/wiki/PulseAudioStoleMyVolumes). Briefly, PulseAudio uses the product of several settings (in my case and perhaps yours, 'Master Front', 'PCM' and 'Front') to achieve the desired volume level. However, the first of those three doesn't actually influence the volume coming out of my headphones, perhaps because they're plugged in at the back of my PC and not the front. The fix seems to be to remove the Master Front horse from the big volume carousel, achieved by:

Alt+F2, run 'gksudo gedit /usr/share/pulseaudio/alsa-mixer/paths/analog-output.conf'
look for [Element Master Front] around line 37
change 'volume = merge' to 'volume = ignore'

This gives a much better result for me. Now the range of settings on the volume widget from 50-100% are useful. 100% corresponds to full volume, and below 50% there is still a continuous range of levels, but they are all too quiet to be useful. Still, 10 volume levels is much better than 1.

[Hugh Warrington (x-launchpad-hughw-org)]

For anyone who may be interested, I just upgraded to Ubuntu 10.10 'Maverick Meerkat', which helpfully undid the edits I had made to the conf file (without asking). The fix as described in #3 still does the trick. To see the effects after editing the config, you may need to 'killall pulseaudio' or maybe log out and back in again.

[Fabio Marconi (fabiomarconi)]

Hello
Is this problem present with the latest updates ?
Thanks
Fabio

[Hugh Warrington (x-launchpad-hughw-org)]

Hi Fabio, can you be more specific? What exactly do you want me to do to determine if the problem is still present?

[Fabio Marconi (fabiomarconi)]

I just want to know if pulseaudio works without workaround
Thanks
Fabio

[Hugh Warrington (x-launchpad-hughw-org)]

Hi Fabio. To me the issue seems to be that the default config file is incorrect. If I revert my edit to /usr/share/pulseaudio/alsa-mixer/paths/analog-output.conf, and restore it to how it was left after my last dist upgrade, then restart pulseaudio, I still have the same problem. So I think the answer to your question in #5 is 'yes'. I have to leave the config edit in place to get the desired behaviour, even after 'apt-get upgrade'.

[Daniel T Chen (crimsun)]

This seems to be caused by http://bazaar.launchpad.net/~ubuntu-audio-dev/pulseaudio/ubuntu.natty/annotate/head%3A/debian/patches/0055-handle-Master-Front.patch. Can we back it out and confirm that it resolves your symptom?

[Daniel T Chen (crimsun)]

Note that we can't wholesale revert the application of that patch. Your symptom is tied to your VIA hardware, which is known not to work correctly. (However, there is no consensus on how to fix it.) Other manufacturers have 'Master Front's that work correctly.

[Hugh Warrington (x-launchpad-hughw-org)]

Hey got an update here. I regularly update the packages on my system, and I'm not sure what package is responsible (new kernel?), but the behaviour seems to have changed for the better. The first indication was after restarting, my music was much quieter than usual, and too quiet even at max volume. Now if I look in alsamixer, adjusting 'Master Front' actually does make a difference to perceived loudness. I reverted the edit I had made to analog-output.conf, and hey presto the volume keys do the right thing, with volume output now ranging from very quiet to max volume, and Master Front/PCM/Front all being adjusted sensibly. Incidentally the 'Headphone' column in alsamixer is now greyed out and disabled. Daniel, I guess the underlying issue with VIA hardware was fixed or worked around? Yay!

[Daniel van Vugt (vanvugt)]

Thank you for reporting this bug to Ubuntu.
Ubuntu 10.04 (lucid) reached end-of-life on May 9, 2013.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

Please upgrade to the latest version and re-test.

[Launchpad Janitor (janitor)]

[Expired for pulseaudio (Ubuntu) because there has been no activity for 60 days.]