AUDIOCTL(8) - System Manager’s Manual #

AUDIOCTL(8) - System Manager’s Manual

NAME #

audioctl - get or set audio driver variables

SYNOPSIS #

audioctl [-nq] [-f file] [-w wait] [name[=value] …]

DESCRIPTION #

The audioctl utility retrieves or sets audio(4) driver variables. The options are as follows:

-f file

Specifies the audio control device or the audio device. The default is /dev/audioctl0.

-n

Suppress printing of the variable name.

-q

Suppress all output when setting a variable.

-w wait

Display variables every wait seconds. audioctl will continue to display variables until interrupted.

name[=value]

Retrieve the specified variable name, or attempt to set it to value. Multiple name[=value] arguments may be given.

If the audio control device is used, then values are only stored in the 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.

The following variable names are available:

**Name**           **Meaning**  
name               device name, as shown by
dmesg(8)  
mode               current device mode (*play*,
*record*,
or both)  
pause              set if not attempting to start  
active             set if playing or recording  
nblks              number of blocks (in frames) in the play buffer  
blksz              number of frames per block  
rate               sample rate in Hz  
encoding           current sample format  
play.channels      number of play channels  
play.bytes         bytes played since playback started  
play.errors        bytes inserted during underruns  
record.channels    number of recording channels  
record.bytes       bytes recorded since device started  
record.errors      bytes dropped during overruns

Encoding names use the following scheme: signedness (s or u) followed by the precision in bits, the byte-order (le or be) , the number of bytes per sample, and the alignment (msb or lsb) . Only the signedness and the precision are mandatory. Examples: u8, s16le, s24le3, s24le4lsb.

FILES #

/dev/audioctlN

audio control devices

/dev/audioN

audio devices

EXAMPLES #

Once per second, display the number of bytes of silence inserted due to buffer underruns (since the device started playback):

# audioctl -w 1 play.errors

Use signed 24-bit samples and 44100Hz sample rate:

# audioctl -f /dev/audio0 encoding=s24 rate=44100

Note the use of /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.

HISTORY #

The audioctl command first appeared in NetBSD 1.3.

OpenBSD 7.5 - January 9, 2023