amixer simple control decreases volume wrong (especially higher decrease for left channel)

[Nicolas Krzywinski]

Binary package hint: alsa-utils

Hello,

after upgrade to Lucid I encountered a bug in amixer:
"amixer sset Master playback 2dB-"
for example sooner or later decreases the volume for front left channel too much, thus de-centering sound output

Here are my versions:
Kernel 2.6.32-21
alsa-utils 1.0.22-0ubuntu5

Soundcard Creative Labs SB X-Fi

Take a look on the attachment how it exploits. You will see its diverting with dB and with hardware values and it is really arbitrary. Of course I checked other values than "1" as well.

[Nicolas Krzywinski (nsk7even)]

Just found this bug https://bugs.launchpad.net/ubuntu/+source/alsa-utils/+bug/557352 and first I thought this could be the same for me ... but it isn't.

To sum up:
alsamixer is working for me perfectly
amixer is working as well with the only exception of decreasing too much with simple control

[Matt (matt-wintergarden)]

I'm experiencing the exact same problem

Ubuntu 10.04 2.6.32-22-generic
alsa-utils 1.0.22-0ubuntu5
C-Media Electronics Inc CM8738

example:
amixer -c 0 set Master 2-
Simple mixer control 'Master',0
  Capabilities: pvolume penum
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 31
  Mono:
  Front Left: Playback 19 [61%]
  Front Right: Playback 19 [61%]

amixer -c 0 set Master 2-
Simple mixer control 'Master',0
  Capabilities: pvolume penum
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 31
  Mono:
  Front Left: Playback 15 [48%]
  Front Right: Playback 17 [55%]

[Raigedas (raigedas)]

i have found that this is the exactly same bug:
http://bugs.gentoo.org/77523
note, the year 2005...