Resume Wikipedia de Advanced Linux sound architecture
Advanced Linux Sound Architecture (ALSA) est un ensemble de logiciels pour enregistrer et jouer des sons, qui est incorporé dans le noyau Linux. Destiné à remplacer Open Sound System (OSS) pour le support des cartes son, il comporte un mixeur audio et une suite de pilotes. Les objectifs initiaux du projet comportent la configuration automatique des cartes son et le support aisé de plusieurs cartes son dans le même système, et ont été largement atteints. Quelques frameworks audio, JACK par exemple, utilisent ALSA pour une édition et un mixage à basse latence et de qualité professionnelle.
Lancé par Jaroslav Kysela, le projet a démarré à partir d’un pilote Linux pour la carte son Gravis Ultrasound en 1998, et a été développé en marge du noyau Linux, jusqu’à son introduction dans la série 2.5 en 2002 (2.5.4-2.5.5). Il remplace OSS dans la version 2.6 bien qu’une couche de rétrocompatibilité existe.
ALSA est distribué sous licence GNU GPL 2.0 et/ou GNU LGPL 2.1.
ALSAMIXER(1) General Commands Manual ALSAMIXER(1)
alsamixer – soundcard mixer for ALSA soundcard driver, with ncurses
alsamixer is an ncurses mixer program for use with the ALSA soundcard
drivers. It supports multiple soundcards with multiple devices.
Help: show available flags.
Select the soundcard to use, if you have more than one. Cards
are numbered from 0 (the default).
Select the mixer device to control.
Select the starting view mode, either playback, capture or all.
Toggle the using of colors.
The top-left corner of alsamixer is the are to show some basic informa‐
tion: the card name, the mixer chip name, the current view mode and the
currently selected mixer item. When the mixer item is switched off,
[Off] is displayed in its name.
Volume bars are located below the basic information area. You can
scroll left/right when all controls can’t be put in a single screen.
The name of each control is shown in the bottom below the volume bars.
The currently selected item is drawn in red and/of emphasized.
Each mixer control with volume capability shows a box and the current
volume filled in that box. The volume percentages are displayed below
the volume bar for left and right channels. For a mono control, only
one value is shown there.
When a mixer control is turned off, M (mute) appears below the volume
bar. When it’s turned on, O in green appears instead. You can toggle
the switch via m key.
When a mixer control has capture capability, the capture flag appears
below the volume bar, too. When the capture is turned off, ——- is
shown. CAPTURE in red appears when the capture switch is turned on.
In addition, L and R letters appear in left and right side to indicate
that left and the right channels are turned on.
Some controls have the enumeration list, and don’t show boxes but only
texts which indicate the currently active item. You can change the
item via up/down keys.
alsamixer has three view modes: playback, capture and all. In the
playback view, only the controls related with playback are shown. Sim‐
ilarly, only the controls for capture (recording) are shown in the cap‐
ture view. The all view mode shows all controls. The current view
mode is displayed in the top-left position together with the mixer
The default view mode is the playback view. You can change it via -V
Each view mode can be switched via keyboard commands, too. See the
alsamixer recognizes the following keyboard commands to control the
soundcard. Commands shown here in upper case can also be given in
lower case. To be reminded of these keystrokes, hit the h key.
The Left and right arrow keys are used to select the channel (or
device, depending on your preferred terminology). You can also use n
(“next”) and p (“previous”).
The Up and Down Arrows control the volume for the currently selected
device. You can also use + or – for the same purpose. Both the left and
right signals are affected. For independent left and right control, see
The B or = key adjusts the balance of volumes on left and right chan‐
M toggles muting for the current channel (both left and right). If the
hardware supports it, you can mute left and right independently by
using , (or <) and . (or >) respectively.
SPACE enables recording for the current channel. If any other channels
have recording enabled, they will have their recording function dis‐
abled first. This only works for valid input channels, of course.
L re-draws the screen.
View Mode Controls
Function keys are used to change view modes. You can switch to the
help mode and the proc info mode via F1 and F2 keys, respectively. On
terminals that can’t use function keys like gnome-terminal, ? and /
keys can be used alternatively for help and proc modes.
F3, F4 and F5 keys are used to switch to playback, capture and all view
mode, respectively. TAB key toggles the current view mode circularly.
Quick Volume Changes
PageUp increases volume by 5.
PageDown decreases volume by 5.
End sets volume to 0.
You can also control left & right levels for the current channel inde‐
pendently, as follows:
[Q | W | E ] — turn UP [ left | both | right ]
[Z | X | C ] — turn DOWN [ left | both | right ]
If the currently selected mixer channel is not a stereo channel, then
all UP keys will work like W, and all DOWN keys will work like X.
The number keys from 0 to 9 are to change the absolute volume quickly.
They correspond to 0 to 90% volume.
Selecting the Sound Card
You can select another sound card by pressing the F6 or S keys. This
will show a list of available sound cards to choose from, and an entry
to enter the mixer device name by hand.
Quit the program with ALT Q, or by hitting ESC. Please note that you
might need to hit ESC twice on some terminals since it’s regarded as a
In alsamixer, the volume is mapped to a value that is more natural for
a human ear. 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 multipli‐
cation 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
Only for controls without dB information, a linear mapping of the hard‐
ware volume register values is used (this is the same algorithm as used
in the old alsamixer).
Some terminal emulators (e.g. nxterm) may not work quite right with
ncurses, but that’s their own damn fault. Plain old xterm seems to be
alsamixer has been written by Tim Janik and been further improved by
This manual page was provided by Paul Winkler
22 May 2009 ALSAMIXER(1)