[Regression] wrong audio volume output stepping for USB speakers

[Luca Ferretti]

Binary package hint: pulseaudio

The behavior of increasing/decreasing audio volume level for my USB speaker (Logitech Z5, for the record) is changed switching from 9.10 (karmic koala) to 10.04 (lucid lynx). Maybe I haven't the proper knowledges to fix this for myself, but this is the default behavior after installing 10.04 :(

* Previous behavior
  Using the USB speakers as audio output, the sound started to be audible when the audio level (in PulseAudio) was about 10%. Then, increasing the level, the sound increased accordingly.

* Current behavior
  Now, in 10.04, the sound from USB speakers starts to be audible when the audio level (in PulseAudio) is more then 80%, then it quickly increase (something like logarithmic) once passed the Base level (89%) and quickly maximize.
Basically, it's impossible to tune the desired audio level.

Those percentages comes from pavucontrol utility. Cross checking values in pavucontrol and alsamixer for this device, I've the following. When AlsaMixer says 0, pavucontrol is lower then 89% (so called Base level by PulseAudio), but some low sounds come from the speakers. When AlsaMixers says 50, PulseAudio says 94% (see attached screenshots).

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: pulseaudio 1:0.9.22~0.9.21+stable-queue-32-g8478-0ubuntu14
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-21-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: luca 1570 F.... pulseaudio
 /dev/snd/controlC2: luca 1570 F.... pulseaudio
 /dev/snd/controlC1: luca 1570 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'SB'/'HDA ATI SB at 0xfe6f4000 irq 16'
   Mixer name : 'Realtek ALC889'
   Components : 'HDA:10ec0889,14627576,00100004'
   Controls : 38
   Simple ctrls : 22
Card1.Amixer.info:
 Card hw:1 'U0x46d0x804'/'USB Device 0x46d:0x804 at usb-0000:00:12.2-6, high speed'
   Mixer name : 'USB Mixer'
   Components : 'USB046d:0804'
   Controls : 2
   Simple ctrls : 1
Card1.Amixer.values:
 Simple mixer control 'Mic',0
   Capabilities: cvolume cvolume-joined cswitch cswitch-joined penum
   Capture channels: Mono
   Limits: Capture 0 - 6144
   Mono: Capture 0 [0%] [6.00dB] [on]
Card2.Amixer.info:
 Card hw:2 'Speakers'/'Logitech Logitech Z-5 Speakers at usb-0000:00:13.0-1, full speed'
   Mixer name : 'USB Mixer'
   Components : 'USB046d:0a13'
   Controls : 2
   Simple ctrls : 1
Date: Sun Apr 25 23:05:43 2010
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Release Candidate amd64 (20100419.1)
ProcEnviron:
 PATH=(custom, user)
 LANG=it_IT.utf8
 SHELL=/bin/bash
SourcePackage: pulseaudio
dmi.bios.date: 12/17/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V4.0
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: 790GX-G65 (MS-7576)
dmi.board.vendor: MICRO-STAR INTERNATIONAL CO.,LTD
dmi.board.version: 1.0
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: MICRO-STAR INTERNATIONAL CO.,LTD
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV4.0:bd12/17/2009:svnMICRO-STARINTERNATIONALCO.,LTD:pnMS-7576:pvr1.0:rvnMICRO-STARINTERNATIONALCO.,LTD:rn790GX-G65(MS-7576):rvr1.0:cvnMICRO-STARINTERNATIONALCO.,LTD:ct3:cvr1.0:
dmi.product.name: MS-7576
dmi.product.version: 1.0
dmi.sys.vendor: MICRO-STAR INTERNATIONAL CO.,LTD

[Luca Ferretti (elle.uca)]

The Unamplified mark in this screenshot coincides with pavucontrol "Base" mark.

This tiny space is unusable, a little move to the right will put volume to a really loud 100%

[Luca Ferretti (elle.uca)]

For the record, the other output device "Internal Audio" works fine

[Luca Ferretti (elle.uca)]

Same behaviour on Fedora 13 Beta, could be an upstream bug.

[Daniel T Chen (crimsun)]

Basically, your hardware is exposing crap dB information. PulseAudio tries to honor the existing dB info provided via the driver, which leads to this bad experience.

See also https://wiki.ubuntu.com/DebuggingSoundProblems/KarmicCaveats#Volume%20range%20anomalies

[Luca Ferretti (elle.uca)]

> Basically, your hardware is exposing crap dB information.

Daniel, thanks, I'll follow the info on debugging page to provide verbose logs. But I still have a some doubts. If in karmic the same hardware was working, why did it started to expose crap on lucid? And this is an issue related to this specific USB speakers model or could effect other USB based audio devices?

[Daniel T Chen (crimsun)]

On Tue, Apr 27, 2010 at 9:58 AM, Luca Ferretti <email address hidden> wrote:
> Daniel, thanks, I'll follow the info on debugging page to provide
> verbose logs. But I still have a some doubts. If in karmic the same
> hardware was working, why did it started to expose crap on lucid? And

PA is very different between Karmic and Lucid. Lucid's version makes
it much more obvious/audible if the dB info is junk.

> this is an issue related to this specific USB speakers model or could
> effect other USB based audio devices?

dB info is always device-specific.

[Corey Woodworth (coreywoodworth)]

In lucid. Unamplified seems to be equivalent to 0%

[Luca Ferretti (elle.uca)]

Added "ignore_dB=1" to "load-module module-udev-detect" in file ~/.pulse/default.pa
"Unamplified" and "Base" marks disappeared from sliders, and volume behavior is now as was in Karmic.

Now, a simple `ubuntu-bug -u 569926 -p alsa-driver` should be enough to add the missing needed info, isn't it? Should I perform it keeping previous changes to default.pa or removing them?

PS I haven't yet installed alsa linux backports package

[Dzmitry Charniachenka (chenka)]

@Luca
Can you advise how the resulting default.pa should look like, please?
I don't have it in ~/.pulse/ and not so experienced with Linux to compose it from scratch.

Should everything go into one (single) line like:
load-module module-udev-detect ignore_dB=1
?

[Dzmitry Charniachenka (chenka)]

Hmm..
This seemingly the same bug
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/531063
suggests adding the PPA ubuntu-audio-dev/ppa and installing linux-alsa-driver-modules-2.6.32-14-generic (or even 2.6.34-rc6 or the latest daily build of 2.6.34)

[Rylee Isitt (rylee-isitt)]

I'm having the same issue with Logitech V20 speakers on Ubuntu 10.04. I've noticed that running alsamixer from the terminal and adjusting the PCM slider controls the volume smoothly. The default mixer that is integrated with the desktop (in Sound Preferences) doesn't work properly with the USB speakers.

By watching alsamixer while adjusting the output volume in the Sound Preferences dialog, I get these results:
- Prior to the first notch, the PCM level is 0 and the sound level is very quiet
- At the first notch, the PCM level jumps to 23 and the sound level is still fairly quiet
- One step above the first notch, the PCM level jumps to 80 and the sound level causes localized earthquakes

So while there is a workaround (using alsamixer), it would be awesome if the Sound Preferences slider worked smoothly. Keep us posted. Thanks!