HardenedBSD/usr.sbin/mixer/mixer.8

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.\" Copyright (c) 2021 Christos Margiolis <christos@FreeBSD.org>
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.Dd August 14, 2024
.Dt MIXER 8
.Os
.Sh NAME
.Nm mixer
.Nd manipulate soundcard mixer controls
.Sh SYNOPSIS
.Nm
.Op Fl f Ar device
.Op Fl d Ar pcmN | N Op Fl V Ar voss_device:mode
.Op Fl os
.Op Ar dev Ns Op Cm \&. Ns Ar control Ns Op Cm \&= Ns Ar value
.Ar ...
.Nm
.Op Fl os
.Fl a
.Nm
.Fl h
.Sh DESCRIPTION
The
.Nm
utility is used to set and display soundcard mixer device controls.
.Pp
The options are as follows:
.Bl -tag -width "-V voss_device:mode"
.It Fl a
Print the values for all mixer devices available in the system
.Pq see Sx FILES .
.It Fl d Ar pcmN | N
Change the default audio card to
.Ar pcmN ,
where N is the unit number (e.g for pcm0, the unit number is 0).
See
.Sx EXAMPLES
on how to list all available audio devices in the system.
.Pp
There is also the possibility of hot-swapping to the new default device if
.Xr virtual_oss 8
exists in the system and is running, in which case the
.Fl V
option needs to be specified as well.
.Pp
Hot-swapping generally cannot happen with plain
.Xr sound 4 ,
so the user has to restart the track in order to get sound coming out of the
new default device.
This is because applications usually open a device at the start of the track
and do not check for default device changes, in order to open the new device
mid-track.
.Xr virtual_oss 8 ,
on the other hand, can do hot-swapping, because it creates a virtual device for
applications to open, and then does all the necessary routing and conversions
to the appropriate device(s).
.Pp
Note that hot-swapping will work only for applications that are using
.Xr virtual_oss 8
devices, and not plain
.Xr sound 4
ones.
.It Fl f Ar device
Open
.Ar device
as the mixer device
.Pq see Sx FILES .
.It Fl h
Print a help message.
.It Fl o
Print mixer values in a format suitable for use inside scripts.
The mixer's header (name, audio card name, ...) will not be printed.
.It Fl s
Print only the recording source(s) of the mixer device.
.It Fl V Ar voss_device:mode
Specify a
.Xr virtual_oss 8
control device, as well as a mode (see below), in order to hot-swap devices.
This option is meant to only be used in combination with the
.Fl d
option.
.Pp
The available modes are as follows:
.Bl -column play
.It Sy Mode Ta Sy Action
.It all Ta Playback and recording
.It play Ta Playback
.It rec Ta Recording
.El
.Pp
The
.Pa mode
part is needed, so that
.Nm
will not accidentally hot-swap both the recording and playback device in
.Xr virtual_oss 8 ,
if only one direction is to be hot-swapped.
.Pp
See
.Sx EXAMPLES
on how to use this option.
.El
.Pp
The list of mixer devices that may be modified are:
.Bd -ragged -offset indent
.Cm vol , bass , treble , synth , pcm , speaker , line , mic , cd , mix ,
.Cm pcm2 , rec ,
.Cm igain , ogain ,
.Cm line1 , line2 , line3 ,
.Cm dig1 , dig2 , dig3 ,
.Cm phin , phout , video , radio ,
and
.Cm monitor .
.Ed
.Pp
Not all mixer devices are available.
.Pp
Without any arguments,
.Nm
displays all information for each one of the mixer's supported devices to
.Ar stdout .
If the
.Ar dev
argument is specified,
.Nm
displays only the values for
.Ar dev .
More than one device may be specified.
.Pp
Commands use the following format:
.Bl -column xxxxxxxxxxxxxxxxxxxxxxxx -offset indent
.It Sy Name Ta Sy Action
.It Ar dev Ta Display all controls
.It Ar dev Ns Cm \&. Ns Ar control Ta Display only the specified control
.It Ar dev Ns Cm \&. Ns Ar control Ns Cm \&= Ns Ar value Ta Set control value
.El
.Pp
The available controls are as follows (replace
.Ar dev
with one of the available devices):
.Sm off
.Bl -column xxxxxxxxxxxxxxxxxxxxxxxx -offset indent
.It Sy Name Ta Sy Value
.It Ar dev Cm .volume Ta Xo
.Ar vol |
.Oo Cm \&+ | Cm \&- Oc Ar lvol Oo % Oc
.Oo Cm \&: Oo Cm \&+ | Cm \&- Oc Ar rvol Oo % Oc Oc
.Xc
.It Ar dev Cm .mute Ta Cm 0 | 1 | ^
.It Ar dev Cm .mute Ta Cm off | on | toggle
.It Ar dev Cm .recsrc Ta Cm ^ | + | - | =
.It Ar dev Cm .recsrc Ta Cm toggle | add | remove | set
.El
.Sm on
.Pp
The
.Ar dev Ns Cm .volume
control modifies a device's volume.
The optional
.Ar lvol
and/or
.Ar rvol
values have to be specified.
The values should typically be decimal numbers between 0 and 1 with at most 2
digits after the decimal point.
A trailing percent sign indicates that the value should be treated as a
percentage of 1.0, rather than an absolute value.
Thus, 70% means the same as 0.7.
If the left or right volume values are prefixed with
.Cm +
or
.Cm - ,
the value following will be used as a relative adjustment, modifying the
current settings by the amount specified.
Note that relative percentages are still relative to 1.0, not to the current
value.
If the volume is currently 0.40 and an adjustment of +20% is specified, then
thet final volume will be set to 0.60.
.Pp
Volume can also be set using the shorthand
.Ar dev Ns Cm =value .
This syntax does not apply to other controls.
.Pp
The
.Ar dev Ns Cm .mute
control (un)mutes a device.
The following values are available:
.Bl -tag -width "xxxxxxxxxx" -offset indent
.It Cm 0 | off
unmutes
.Ar dev
.It Cm 1 | on
mutes
.Ar dev
.It Cm ^ | toggle
toggles the mute of
.Ar dev
.El
.Pp
The
.Ar dev Ns Cm .recsrc
control modifies the recording sources of a mixer.
.Nm
marks devices which can be used as a recording source with
.Sy rec .
Recording sources are marked with
.Sy src .
To modify the recording source you can use one of the following modifiers
on a
.Sy rec
device:
.Bl -tag -width "xxxxxxxxxx" -offset indent
.It Cm ^ | toggle
toggles
.Ar dev
of possible recording devices
.It Cm + | add
adds
.Ar dev
to possible recording devices
.It Cm - | remove
removes
.Ar dev
from possible recording devices
.It Cm = | set
makes
.Ar dev
the only recording device.
.El
.Sh FILES
.Bl -tag -width /dev/mixerN -compact
.It Pa /dev/mixerN
The mixer device, where
.Ar N
is the number of that device, for example
.Ar /dev/mixer0 .
PCM cards and mixers have a 1:1 relationship, which means that
.Pa /dev/mixer0
is the mixer for
.Pa /dev/pcm0
and so on.
By default,
.Nm
prints both the audio card's number and the mixer associated with it
in the form of
.Ar pcmN:mixer .
The
.Pa /dev/mixer
file, although it does not exist in the filesystem, points to the default
mixer device and is the file
.Nm
opens when the
.Fl f Ar device
option has not been specified.
.El
.Sh EXAMPLES
List all available audio devices in the system:
.Bd -literal -offset indent
$ mixer -a | grep ^pcm
.Ed
.Pp
Increase the
.Cm vol
device's volume by 5%:
.Bd -literal -offset indent
$ mixer vol=+5%
.Ed
.Pp
Change the volume for the
.Cm vol
device of the
.Pa /dev/mixer0
mixer device to 0.65:
.Bd -literal -offset indent
$ mixer -f /dev/mixer0 vol.volume=0.65
.Ed
.Pp
Increase the
.Cm mic
device's left volume by 0.10 and decrease the right
volume by 0.05:
.Bd -literal -offset indent
$ mixer mic.volume=+0.10:-0.05
.Ed
.Pp
Toggle the mute for
.Cm vol :
.Bd -literal -offset indent
$ mixer vol.mute=toggle
.Ed
.Pp
Add
.Cm mic
and remove
.Cm line
from the recording devices:
.Bd -literal -offset indent
$ mixer mic.recsrc=add line.recsrc=remove
.Ed
.Pp
Dump
.Pa /dev/mixer0
information to a file and retrieve back later:
.Bd -literal -offset indent
$ mixer -f /dev/mixer0 -o > info
\&...
$ mixer -f /dev/mixer0 `cat info`
.Ed
.Pp
Suppose
.Xr virtual_oss 8
is running with
.Pa /dev/vdsp.ctl
as its control device, and
.Pa pcm0
as the playback device.
Change the default device to
.Pa pcm1 ,
and hot-swap to it for both recording and playback in
.Xr virtual_oss 8 :
.Bd -literal -offset indent
$ mixer -d pcm1 -V /dev/vdsp.ctl:all
.Ed
.Sh SEE ALSO
.Xr mixer 3 ,
.Xr sound 4 ,
.Xr sysctl 8 ,
.Xr virtual_oss 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 2.0.5
and was rewritten completely in
.Fx 14.0 .
.Sh AUTHORS
.An Christos Margiolis Aq Mt christos@FreeBSD.org