.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.3.
.TH UNABLE "1" "August 2026" "unable to open control device '/dev/v4l2loopback': No such file or directory" "User Commands"
.SH NAME
unable \- control v4l2 loopback devices
.SH SYNOPSIS
.B v4l2loopback-ctl
[\fI\,OPTIONS\/\fR]
.br
.B v4l2loopback-ctl
\fI\,add \/\fR[\fI\,OPTIONS\/\fR] [\fI\,<outputdevice> \/\fR[\fI\,<capturedevice>\/\fR]]
.br
.B v4l2loopback-ctl
\fI\,delete <device>\/\fR
.br
.B v4l2loopback-ctl
\fI\,list \/\fR[\fI\,OPTIONS\/\fR]
.br
.B v4l2loopback-ctl
\fI\,query \/\fR[\fI\,OPTIONS\/\fR] \fI\,<device>\/\fR
.br
.B v4l2loopback-ctl
\fI\,set-fps <device> <fps>\/\fR
.br
.B v4l2loopback-ctl
\fI\,get-fps <device>\/\fR
.br
.B v4l2loopback-ctl
\fI\,set-caps <device> <caps>\/\fR
.br
.B v4l2loopback-ctl
\fI\,get-caps <device>\/\fR
.br
.B v4l2loopback-ctl
\fI\,set-timeout-image \/\fR[\fI\,OPTIONS\/\fR] \fI\,<device> <image>\/\fR
.SH DESCRIPTION
Manage v4l2 loopback devices.
.PP
The general invocation uses a verb (like 'add' or 'delete') that defines
an action to be executed. Each verb has their own options and arguments.
.SH OPTIONS
.HP
\fB\-h\fR, \-?, \fB\-\-help\fR: print this help and exit
.HP
\fB\-v\fR, \fB\-\-version\fR: print version and exit
.SH "VERBS AND THEIR ARGUMENTS"
.SS "v4l2loopback-ctl add [OPTIONS] [<outputdevice> [<capturedevice>]]:"
.IP
create/add a new loopback\-device
.TP
\fB\-b\fR <num>, \fB\-\-buffers\fR <num>
buffers to queue
.TP
\fB\-h\fR <h>, \fB\-\-max\-height\fR <h>
maximum allowed frame height
.TP
\fB\-n\fR <name>, \fB\-\-name\fR <name>
pretty name for the device
.HP
\fB\-o\fR <num>, \fB\-\-max\-openers\fR <num> maximum allowed concurrent openers
.TP
\fB\-v\fR, \fB\-\-verbose\fR
verbose mode (print properties of device after successfully creating it)
.TP
\fB\-w\fR <w>, \fB\-\-max\-width\fR <w>
maximum allowed frame width
.TP
\fB\-x\fR <x>, \fB\-\-exclusive\-caps\fR <x>
whether to announce OUTPUT/CAPTURE capabilities exclusively
.TP
\fB\-\-min\-width\fR <w>
minimum allowed frame width
.TP
\fB\-\-min\-height\fR <w>
minimum allowed frame height
.TP
\-?, \fB\-\-help\fR
print this help and exit
.TP
<outputdevice>
if given, create a specific device (otherwise just create a free one).
.IP
either specify a device name (e.g. '/dev/video1') or a device number ('1').
.TP
<capturedevice>
if given, use separate output & capture devices (otherwise they are the same).
.SS "v4l2loopback-ctl delete <device>:"
.IP
delete/remove an unused loopback device
.TP
<device>
can be given one more more times (to delete multiple devices at once).
either specify a device name (e.g. '/dev/video1') or a device number ('1').
.SS "v4l2loopback-ctl list [OPTIONS]:"
.IP
list all available loopback\-devices
.TP
\fB\-e\fR, \fB\-\-escape\fR
escape control\-characters in (device) names
.TP
\fB\-h\fR, \fB\-\-help\fR
print this help and exit
.SS "v4l2loopback-ctl query [OPTIONS] <device>:"
.IP
query information about a loopback device
.TP
\fB\-e\fR, \fB\-\-escape\fR
escape control\-characters in (device) names
.TP
\fB\-h\fR, \fB\-\-help\fR
print this help and exit
.TP
<device>
can be given one more more times (to query multiple devices at once).
either specify a device name (e.g. '/dev/video1') or a device number ('1').
.SS "v4l2loopback-ctl set-fps <device> <fps>:"
.IP
set the default framerate for a loopback device
.TP
<device>
either specify a device name (e.g. '/dev/video1') or a device number ('1').
.TP
<fps>
frames per second, either as integer ('30') or fraction ('50/2').
.SS "v4l2loopback-ctl get-fps <device>:"
.IP
query the framerate of a loopback device
.SS "v4l2loopback-ctl set-caps <device> <caps>:"
.IP
set format/dimension/framerate of a loopback device
.TP
<device>
either specify a device name (e.g. '/dev/video1') or a device number ('1').
.TP
<caps>
format specification as '<fourcc>:<width>x<height>@<fps>' (e.g. 'UYVY:1024x768@60/1')
unset the current caps with the special value 'any'
.SS "v4l2loopback-ctl get-caps <device>:"
.IP
get current format/dimension/framerate of a loopback device
.SS "v4l2loopback-ctl set-timeout-image [OPTIONS] <device> <image>:"
.IP
set a fallback image to be used if a video producer does not send new frames in time.
.TP
<flags>
any of the following flags may be present
.TP
\fB\-h\fR, \fB\-\-help\fR
print this help and exit
.TP
\fB\-t\fR <timeout>, \fB\-\-timeout\fR <timeout>
timeout (in ms)
.TP
\fB\-v\fR, \fB\-\-verbose\fR
raise verbosity (print what is being done)
.TP
<device>
either specify a device name (e.g. '/dev/video1') or a device number ('1').
.TP
<image>
image file
.SH "REPORTING BUGS"
Issue tracker: https://github.com/umlaeute/v4l2loopback/issues
.br
Security Issue tracker: https://git.iem.at/zmoelnig/v4l2loopback/\-/issues
.PP
utils/v4l2loopback\-ctl v0.15.4