alsa-utils/alsactl/alsactl.1

.TH ALSACTL 1 "25 Nov 1998"
.SH NAME
alsactl \- advanced controls for ALSA soundcard driver

.SH SYNOPSIS

\fBalsactl\fP [\fIoptions\fP] [\fIstore\fP|\fIrestore\fP] <card #>

.SH DESCRIPTION
\fBalsactl\fP is used to control advanced settings for the ALSA
soundcard drivers. It supports multiple soundcards.

.SH INVOKING

\fBalsactl\fP [\fIoptions\fP] [\fIstore\fP|\fIrestore\fP] <card #>

.SS Commands

\fIstore\fP saves the current driver setup for the selected soundcard
to the configuration file.

\fIrestore\fP loads driver setup for the selected soundcard from the configuration file.

If no soundcards are specified, setup for all cards will be saved or
loaded.

.SS Options

.TP
\fI-h, --help\fP 
Help: show available flags and commands.

.TP
\fI-f, --f\fP file
Select the configuration file to use. The default is /etc/asound.conf

.TP
\fI-d, --debug\fP
Use debug mode: a bit more verbose.

.TP
\fI-v, --version\fP
Print alsactl version number.

.SH FILES
\fI/etc/asound.conf\fP (or whatever file you specify with the
\fB-f\fP flag) is used to store current settings for your
soundcards. The settings include all the usual soundcard mixer
settings.  More importantly, alsactl is
capable of controlling other card-specific features that mixer apps
usually don't know about.

The configuration file is generated automatically by running
\fBalsactl store\fP. Editing the configuration file by hand may be
necessary for some soundcard features (e.g. enabling/disabling
automatic mic gain, digital outputs, joystick/game ports, some MIDI
routing options, etc.).

.SS Configuration File Syntax

There are some terms in the config file that bear explaining. The
"capabilities" comments before each line will tell you which flags you
can set for each channel. The comments start with semicolons. To set a
flag, simply add it to the channel() line you want.

.TP
\fIhardware-mute\fP 
The soundcard itself is capable of muting the channel.
Otherwise, kernel midlevel code will set the volume to minimum when an
application requests muting on this channel.

.TP
\fIjoin-mute\fP
Muting this channel can \fBonly\fP be
toggled for left and right at the same time, \fBnot\fP independently
-- even if you can control the volumes for left and right independently!

.TP
\fIstereo\fP
The channel is stereo.

.TP
\fIrecord\fP
Use the channel as a recording source.

.TP
\fIjoin-record\fP
Recording from this channel can only be toggled for \fBboth\fP left
and right at once; they cannot be toggled independently.

.TP
\fIrecord-by-mute\fP
Allow recording the channel even if it's muted, so you can avoid
feeding your record source to the speakers. Not all hardware supports this.

.TP
\fIexternal-input\fP
This flag is purely informational: it tells you that the channel
controls a signal from an external input (like Line-In or CD). This
serves to distinguish external source channels from onboard
source channels (like OPL-3 synth), which don't have this flag set.

.TP
\fIdigital\fP
If you have a card with digital outputs and/or inputs, this flag
toggles digital output/input for the channel.

.PP
Another feature of the configuration file is the \fIboolean\fP switches
which are used to toggle certain card-specific advanced features. For
example:

    ; Type is 'bool'.
    switch( "MIC Gain", false )

This shows that my card has a switchable mic gain, and that it's
currently turned off. To turn it on, just change "false" to "true" and
run \fBalsactl restore\fP.


.SH EXAMPLES

Let's say I have this entry in /etc/asound.conf for my PCM output.

    ; Capabilities: stereo hardware-mute digital.
    ; Accepted channel range is from 0 to 63.
    channel( "PCM", stereo( 40 mute, 50 mute ) )

When \fBalsactl restore\fP is run, volume will be set to 40 for the left
and 50 for the right, but both will be muted (by hardware).


.SH SEE ALSO
\fB
amixer(1),
alsamixer(1),
aplay(1)
\fP

.SH BUGS 
None known.

.SH AUTHOR
\fBalsactl\fP is by Jaroslav Kysela <perex@jcu.cz>
This document is by Paul Winkler <zarmzarm@erols.com>.