.\" $OpenBSD: audioctl.1,v 1.29 2016/06/21 06:32:00 ratchov Exp $
.\" $NetBSD: audioctl.1,v 1.7 1998/04/27 16:55:23 augustss Exp $
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.\" Author: Lennart Augustsson
.\"
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.Dd $Mdocdate: June 21 2016 $
.Dt AUDIOCTL 1
.Os
.Sh NAME
.Nm audioctl
.Nd get or set audio driver variables
.Sh SYNOPSIS
.Nm audioctl
.Op Fl f Ar file
.Nm audioctl
.Op Fl n
.Op Fl f Ar file
.Ar name ...
.Nm audioctl
.Op Fl nq
.Op Fl f Ar file
.Ar name Ns = Ns Ar value ...
.Sh DESCRIPTION
The
.Nm
utility retrieves or sets
.Xr audio 4
driver variables.
The options are as follows:
.Bl -tag -width Ds
.It Fl f Ar file
Specifies the audio control device or the audio device.
The default is
.Pa /dev/audioctl0 .
.It Fl n
Suppress printing of the variable name.
.It Fl q
Suppress all output when setting a variable.
.It Ar name Ns = Ns Ar value
Attempt to set the specified variable
.Ar name
to
.Ar value .
.El
.Pp
If the audio control device is used, then values are only stored in the
.Xr audio 4
driver; they will be submitted to the hardware the next time the
device is opened for playback or recording.
If the audio device is used instead of the control device,
then values are negotiated with the hardware immediately; this requires
exclusive access to the device.
Variables may only be changed if the device is not opened for
playback or recording by another process.
.Pp
The following variable names are available:
.Bl -column "record.channels"
.It Sy Name Ta Sy Meaning
.It name Ta device name as shown by
.Xr dmesg 8
.It mode Ta current device mode (
.Va play ,
.Va record
or both)
.It pause Ta set if not attempting to start
.It active Ta set if playing or recording
.It nblks Ta number of blocks (in frames) in the play buffer
.It blksz Ta number of frames per block
.It rate Ta sample rate in Hz
.It encoding Ta current sample format
.It play.channels Ta number of play channels
.It play.bytes Ta bytes played since playback started
.It play.errors Ta bytes inserted during underruns
.It record.channels Ta number of recording channels
.It record.bytes Ta bytes recorded since device started
.It record.errors Ta bytes dropped during overruns
.El
.Pp
Encoding names use the following scheme: signedness
.Po
.Va s
or
.Va u
.Pc
followed
by the precision in bits, the byte-order
.Po
.Va le
or
.Va be
.Pc ,
the number of
bytes per sample, and the alignment
.Po
.Va msb
or
.Va lsb
.Pc .
Only the signedness and the precision are mandatory.
Examples:
.Va u8 , s16le , s24le3 , s24le4lsb .
.Sh FILES
.Bl -tag -width /dev/audioctl0
.It Pa /dev/audioctlN
audio control devices
.It Pa /dev/audioN
audio devices
.El
.Sh EXAMPLES
Display the number of bytes of silence inserted during play buffer
underruns since device started:
.Bd -literal -offset indent
$ audioctl play.errors
.Ed
.Pp
Use signed 24-bit samples and 44100Hz sample rate:
.Bd -literal -offset indent
$ audioctl -f /dev/audio0 encoding=s24 rate=44100
.Ed
.Pp
Note the use of
.Pa /dev/audio0 ,
to force negotiation with the hardware.
If the above parameters are not supported by the
hardware, then supported ones will be selected instead.
.Sh SEE ALSO
.Xr aucat 1 ,
.Xr cdio 1 ,
.Xr mixerctl 1 ,
.Xr audio 4 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
command first appeared in
.Nx 1.3 .