Ubuntu
pulseaudio package

pulseaudio maximum volume attenuated by alsa mixer setting

Bug #274884 reported by Jeffrey Baker
14
This bug affects 2 people
Affects Status Importance Assigned to Milestone
pulseaudio (Ubuntu)
Fix Released
Wishlist
Unassigned

Bug Description

Binary package hint: pulseaudio

The problem: alsa mixer settings are restored before pulseaudio is started, and therefore pulseaudio's maximum output is scaled downware by the alsa mixer setting. Thus you can turn your volume all the way up in the pulseaudio mixer and still only get half volume. To exacerbate the problem, pulseaudio hides the underlying alsa mixer device, so you have to kill pulseaudio to fix it.

How to reproduce:

1) Kill off pulseaudio.
2) Using ALSA mixer, set your volume to 50%
3) Reboot
4) Notice that all your sound outputs are now really quiet
5) Start alsamixer, note that you can't change anything
6) Kill pulse audio again
7) Start alsamixer again to fix the problem
8) Restart pulseaudio
9) Now everything works fine

Proposed solution: pulseaudio should set the underlying hardware mixer devices to 100% before it starts.

Revision history for this message
Jeffrey Baker (jwbaker) wrote :

pulseaudio 0.9.10-2ubuntu6 and alsa-utils 1.0.17-0ubuntu2 on Intrepid Alpha.

Revision history for this message
Daniel T Chen (crimsun) wrote :

Setting the mixer level(s) of the underlying playback and recording devices to 100% potentially results in horrible distortion. I can reproduce such a symptom on 3 different (Conexant, Sigmatel, and Realtek) HDA codecs in addition to USB audio.

Revision history for this message
Jeffrey Baker (jwbaker) wrote :

The fact that some dodgy hardware can be overdriven doesn't change the bug here: pulseaudio can't let alsa-utils set arbitrary mixer levels, and then disable the mixers. If it does, it risks leaving the outputs muted, too quiet, or as you point out, clipping. Pulseaudio should set the mixers to a reasonable place before it disables them.

Revision history for this message
Daniel T Chen (crimsun) wrote :

What is "reasonable"?

Revision history for this message
Daniel T Chen (crimsun) wrote :

Also, you do not need to kill PulseAudio to adjust the underlying ALSA mixer element control levels. Just use the direct hw device, e.g., amixer -Dhw:0

Revision history for this message
Daniel T Chen (crimsun) wrote :

cf. upstream flat-volume work in git HEAD

Changed in pulseaudio:
importance: Undecided → Low
status: New → Confirmed
Daniel T Chen (crimsun)
Changed in pulseaudio:
importance: Low → Wishlist
status: Confirmed → Fix Committed
Revision history for this message
Daniel T Chen (crimsun) wrote :

Fixed in karmic.

Changed in pulseaudio (Ubuntu):
status: Fix Committed → Fix Released
Revision history for this message
alphablue52 (torsten-doerschel) wrote :

Not fixed in Karma:

How to reproduce:
- open pavucontrol (0,9,8+git20090701-0ubuntu2) and an alsamixer of your choice (e.g. kmix)
- start an audiostream
- adjust volume at alsa
- switch to pavucontrol window, et voila: it changes the alsamixer settings.

I am a victim of the horrible distortions when PCM is >80%.

Proposed solution: pulseaudio should NOT change ANYTHING at the device mixer settings and behave like "internal volume" controls of most media software.

Altermative solution: pulseaudio adapts ALL mixer possibilities of Alsamixer, and not just one main mxer, that sets PCM to 100% and than ajusts only main out.

Revision history for this message
Daniel T Chen (crimsun) wrote : Re: [Bug 274884] Re: pulseaudio maximum volume attenuated by alsa mixer setting

@alphablue52
Your distortion is not a PA issue; it's a linux issue. Please file a
separate bug using "ubuntu-bug alsa-base". We need the codec dump to
properly fix it.

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