mirror of
https://github.com/alsa-project/alsa-utils
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152 lines
4.1 KiB
Groff
152 lines
4.1 KiB
Groff
.TH ALSACTL 1 "25 Nov 1998"
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.SH NAME
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alsactl \- advanced controls for ALSA soundcard driver
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.SH SYNOPSIS
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\fBalsactl\fP [\fIoptions\fP] [\fIstore\fP|\fIrestore\fP] <card #>
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.SH DESCRIPTION
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\fBalsactl\fP is used to control advanced settings for the ALSA
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soundcard drivers. It supports multiple soundcards. If your card has
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features that you can't seem to control from a mixer application,
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you have come to the right place.
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.SH INVOKING
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\fBalsactl\fP [\fIoptions\fP] [\fIstore\fP|\fIrestore\fP] <card #>
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.SS Commands
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\fIstore\fP saves the current driver setup for the selected soundcard
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to the configuration file.
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\fIrestore\fP loads driver setup for the selected soundcard from the configuration file.
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If no soundcards are specified, setup for all cards will be saved or
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loaded.
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.SS Options
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.TP
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\fI-h, --help\fP
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Help: show available flags and commands.
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.TP
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\fI-f, --f\fP file
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Select the configuration file to use. The default is /etc/asound.conf
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.TP
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\fI-d, --debug\fP
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Use debug mode: a bit more verbose.
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.TP
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\fI-v, --version\fP
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Print alsactl version number.
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.SH FILES
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\fI/etc/asound.conf\fP (or whatever file you specify with the
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\fB-f\fP flag) is used to store current settings for your
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soundcards. The settings include all the usual soundcard mixer
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settings. More importantly, alsactl is
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capable of controlling other card-specific features that mixer apps
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usually don't know about.
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The configuration file is generated automatically by running
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\fBalsactl store\fP. Editing the configuration file by hand may be
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necessary for some soundcard features (e.g. enabling/disabling
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automatic mic gain, digital output, joystick/game ports, some future MIDI
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routing options, etc).
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.SS Configuration File Syntax
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There are some terms in the config file that bear explaining. The
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"capabilities" comments before each line tells you some
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characteristics of each channel. This is purely informational; these
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are not flags you can set. Capabilities are listed below.
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.TP
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\fIhardware-mute\fP
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The soundcard itself is capable of muting the channel.
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Otherwise, kernel midlevel code will set the volume to minimum when an
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application requests muting on this channel.
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.TP
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\fIjoin-mute\fP
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Muting this channel can \fBonly\fP be
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toggled for left and right at the same time, \fBnot\fP independently
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-- even if you can control the volumes for left and right independently!
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.TP
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\fIstereo\fP
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The channel is stereo.
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.TP
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\fIrecord\fP
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The channel may be used as a recording source.
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.TP
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\fIjoin-record\fP
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Recording from this channel can only be toggled for \fBboth\fP left
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and right at once; they cannot be toggled independently.
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.TP
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\fIrecord-by-mute\fP
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This channel can be recorded even if it's muted, so you can avoid
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feeding your record source back to the speakers.
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.TP
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\fIexternal-input\fP
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The channel
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controls a signal from an external input (like Line-In or CD). This
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serves to distinguish external source channels from onboard
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source channels (like OPL-3 synth).
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.TP
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\fIdigital\fP
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This channel is fed to an onboard digital mixer for possible hardware
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processing (for instance, surround-sound processing if your card has it).
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.PP
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The configuration file also has \fIboolean switches\fP
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which are used to toggle certain card-specific advanced features. For
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example:
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; Type is 'bool'.
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switch( "MIC Gain", false )
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This shows that my card has a switchable mic gain, and that it's
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currently turned off. To turn it on, just change "false" to "true,"
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save the config file, and run \fBalsactl restore\fP.
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.SH EXAMPLES
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Let's say I have this entry in /etc/asound.conf for my PCM output.
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; Capabilities: stereo hardware-mute digital.
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; Accepted channel range is from 0 to 63.
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channel( "PCM", stereo( 40 mute, 50 mute ))
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When \fBalsactl restore\fP is run, the PCM volume will be set
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to 40 for the left and 50 for the right, but both will be
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muted. Since this card supports \fIhardware-mute\fP, muting will be done by
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hardware rather than by zeroing the levels.
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.SH SEE ALSO
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\fB
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amixer(1),
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alsamixer(1),
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aplay(1)
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\fP
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.SH BUGS
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None known.
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.SH AUTHOR
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\fBalsactl\fP is by Jaroslav Kysela <perex@suse.cz>
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This document is by Paul Winkler <zarmzarm@erols.com>.
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