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SNDIOCTL(1) General Commands Manual SNDIOCTL(1)

sndioctlmanipulate audio device controls

sndioctl [-dimnqv] [-f device] [command ...]

The sndioctl utility can display or manipulate controls of sndio(7) audio devices, like the output level. The options are as follows:

Dump the raw list of available controls and exit. Useful as a debugging tool.
device
Use this sndio(7) audio device.
Display characteristics of requested controls instead of their values.
Monitor and display audio controls changes.
Suppress printing of the variable name.
Suppress all printing when setting a variable.
Enable verbose mode, a.k.a. multi-channel mode. By default controls affecting different channels of the same stream are disguised as a single mono control to hide details that are not essential.

If no commands are specified all valid controls are displayed on . Unless -d, -m, -n, or -i are used, displayed lines are valid commands. The set of available controls depends on the audio device.

Commands use the following two formats to display and change controls respectively:

group/stream[channel].function
group/stream[channel].function=value

On the left-hand side are specified the control group (if any), the affected stream name, and the optional channel number. Examples of left-hand side terms:

output.level
output[0].level

If the channel number (including the brackets) is omitted, the command is applied to all channels.

Values are numbers between 0 and 1. Two-state controls (switches) take either 0 or 1 as value, typically corresponding to the and states respectively.

If a decimal is prefixed by the plus (minus) sign then the given value is added to (subtracted from) the current value of the control. If "!" is used instead of a number, then the switch is toggled.

Increase the level control affecting all output channels by 10% of the maximum:

$ sndioctl output.level=+0.1

Mute all output channels:

$ sndioctl output.mute=1

Toggle the above mute control:

$ sndioctl output.mute=!

Allow audio recording and set all input channels to 50%:

# sysctl kern.audio.record=1
$ sndioctl input.mute=0 input.level=0.5

sioctl_open(3)

May 27, 2020 OpenBSD-current