[Pkg-alsa-devel] Bug#590586: [libasound2] amixer relative adjustments adjust too much

[Florian Zumbiehl]

Package: libasound2
Version: 1.0.23-1

This is what I observe:

| $ amixer set PCM,0 10%-
| Simple mixer control 'PCM',0
|   Capabilities: volume pswitch cswitch penum
|   Playback channels: Front Left - Front Right
|   Capture channels: Front Left - Front Right
|   Limits: 0 - 31
|   Front Left: 0 [0%] [-50.00dB] Playback [on] Capture [off]
|   Front Right: 0 [0%] [-50.00dB] Playback [on] Capture [off]
| $ amixer set PCM,0 10%+
| Simple mixer control 'PCM',0
|   Capabilities: volume pswitch cswitch penum
|   Playback channels: Front Left - Front Right
|   Capture channels: Front Left - Front Right
|   Limits: 0 - 31
|   Front Left: 8 [26%] [-34.00dB] Playback [on] Capture [off]
|   Front Right: 8 [26%] [-34.00dB] Playback [on] Capture [off]
| $ amixer set PCM,0 10%+
| Simple mixer control 'PCM',0
|   Capabilities: volume pswitch cswitch penum
|   Playback channels: Front Left - Front Right
|   Capture channels: Front Left - Front Right
|   Limits: 0 - 31
|   Front Left: 16 [52%] [-18.00dB] Playback [on] Capture [off]
|   Front Right: 16 [52%] [-18.00dB] Playback [on] Capture [off]
| $ amixer set PCM,0 10%+
| Simple mixer control 'PCM',0
|   Capabilities: volume pswitch cswitch penum
|   Playback channels: Front Left - Front Right
|   Capture channels: Front Left - Front Right
|   Limits: 0 - 31
|   Front Left: 24 [77%] [-2.00dB] Playback [on] Capture [off]
|   Front Right: 24 [77%] [-2.00dB] Playback [on] Capture [off]

I previously had libasound2 from lenny installed, where I don't remember
the exact adjustment steps performed by amixer, but they certainly were a
lot smaller, and a lot closer to the requested change. After installing
libasound2 1.0.23-1 from testing, the behaviour changed to what I
pasted above, still with the amixer from lenny's alsa-utils. An upgrade
to alsa-utils 1.0.23-2 did not fix the problem. As the problem does not
seem to depend on the alsa-utils version, I assume the bug to be in
libasound2.