At Thu, 8 Mar 2012 17:30:02 +0100, Elimar Riesebieter wrote: > > severity 663090 normal > forwarded 663090 alsa-de...@alsa-project.org > thanks > > > * Adam Lee <adam8...@gmail.com> [2012-03-08 20:36 +0800]: > > > Package: alsa-utils > > Version: 1.0.25-1 > > Severity: important > > > > > > db is not linear, but amixer believe it is. > > > > "amixer get Master" says "Limits: Playback 0 - 74", then everytime I run > > "amixer -q sset Master 10%-", there is 8db dec. > > > > For example, at first Master is 100% and 0db, both alsamixer and amixer > > think it is, and after I run "amixer -q sset Master 10%-", both > > alsamixer and amixer says Master is -8.00db, but alsamixer says it is > > 72%, amixer says it is 89%. > > > > alsamixer is right, amixer calc and set wrongly.
No, both are correct. You are dreaming too much on the world unified percentage representation :) The percentage in amixer has nothing to do with dB level. It's just the percentage of the raw value range of that mixer element. Thus showing 89% is correct. It's 10% down from 100% (1% is because of the resolution of the raw values). Now, alsamixer shows the percentage in a different way. It's explained well in the source code (alsamixer/volume_mapping.c), but not mentioned in the man page, unfortunately. * The mapping is designed so that the position in the interval is proportional * to the volume as a human ear would perceive it (i.e., the position is the * cubic root of the linear sample multiplication factor). For controls with * a small range (24 dB or less), the mapping is linear in the dB values so * that each step has the same size visually. Only for controls without dB * information, a linear mapping of the hardware volume register values is used * (this is the same algorithm as used in the old alsamixer). The percentage representation in alsamixer corresponds to this mapping, thus it's neither dB nor linear percent. Takashi > > Several months ago, they both right, and I upgraded, and amixer messed > > up. Please fix it. Thank you. > > > > FYI, my hardware is: > > "HDA-Intel" "Conexant CX20585" "HDA:14f15069,17aa214c,00100302 > > HDA:14f12c06,17aa2122,00100000" "0x17aa" "0x215e" > > > > > > -- System Information: > > Debian Release: wheezy/sid > > APT prefers unstable > > APT policy: (500, 'unstable') > > Architecture: amd64 (x86_64) > > > > Kernel: Linux 3.2.0-1-amd64 (SMP w/4 CPU cores) > > Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) > > Shell: /bin/sh linked to /bin/dash > > > > Versions of packages alsa-utils depends on: > > ii dialog 1.1-20120215-1 > > ii libasound2 1.0.25-2 > > ii libc6 2.13-27 > > ii libncursesw5 5.9-4 > > ii libsamplerate0 0.1.8-3 > > ii libtinfo5 5.9-4 > > ii linux-sound-base 1.0.23+dfsg-4 > > ii lsb-base 3.2+Debian29 > > ii module-init-tools 6-1 > > ii whiptail 0.52.14-8 > > > > Versions of packages alsa-utils recommends: > > ii alsa-base 1.0.23+dfsg-4 > > ii pciutils 1:3.1.8-2 > > > > alsa-utils suggests no packages. > > > > -- no debconf information > > > > > > > > _______________________________________________ > > Pkg-alsa-devel mailing list > > pkg-alsa-de...@lists.alioth.debian.org > > http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-alsa-devel > > > > -- > The path to source is always uphill! > -unknown- > _______________________________________________ > Alsa-devel mailing list > alsa-de...@alsa-project.org > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel > -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
