Bug#818228: pavucontrol: Percentages do not match Decibels in volume sliders

[Thomas Grüttmüller]

Package: pavucontrol
Version: 2.0-3
Severity: normal

Dear Maintainer,

in pavucontrol, the volume sliders show two values, percantages and dB values.
These values however, do not match.

50 % volume should be about −6.02 dB, but pavucontrol shows −18.09 dB.
25 % volume should be about −12.04 dB, but pavucontrol shows −35.81 dB.
10 % volume should be exactly −20 dB, but pavucontrol shows −59.68 dB.

My ear tells me that the resulting volume corresponds to the dB values, not the
percentages, so when I set the slider to 50 %, I actually get 12.5 %.

So I guess, this is what happens: pavucontrol uses a linear slider, then
converts the values to dB using an incorrect formula, and then uses the wrong
dB values to set the volume.



-- System Information:
Debian Release: 8.3
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages pavucontrol depends on:
ii  libatk1.0-0              2.14.0-1
ii  libatkmm-1.6-1           2.22.7-2.1
ii  libc6                    2.19-18+deb8u3
ii  libcairo-gobject2        1.14.0-2.1
ii  libcairo2                1.14.0-2.1
ii  libcairomm-1.0-1         1.10.0-1.1
ii  libcanberra-gtk3-0       0.30-2.1
ii  libcanberra0             0.30-2.1
ii  libgcc1                  1:4.9.2-10
ii  libgdk-pixbuf2.0-0       2.31.1-2+deb8u4
ii  libglib2.0-0             2.42.1-1
ii  libglibmm-2.4-1c2a       2.42.0-1
ii  libgtk-3-0               3.14.5-1+deb8u1
ii  libgtkmm-3.0-1           3.14.0-1
ii  libpango-1.0-0           1.36.8-3
ii  libpangocairo-1.0-0      1.36.8-3
ii  libpangomm-1.4-1         2.34.0-1.1
ii  libpulse-mainloop-glib0  5.0-13
ii  libpulse0                5.0-13
ii  libsigc++-2.0-0c2a       2.4.0-1
ii  libstdc++6               4.9.2-10
ii  libx11-6                 2:1.6.2-3

Versions of packages pavucontrol recommends:
ii  pulseaudio  5.0-13

pavucontrol suggests no packages.

-- no debconf information