NAME

       unable - control v4l2 loopback devices

SYNOPSIS

       v4l2loopback-ctl [OPTIONS]
       v4l2loopback-ctl add [OPTIONS] [<outputdevice> [<capturedevice>]]
       v4l2loopback-ctl delete <device>
       v4l2loopback-ctl list [OPTIONS]
       v4l2loopback-ctl query [OPTIONS] <device>
       v4l2loopback-ctl set-fps <device> <fps>
       v4l2loopback-ctl get-fps <device>
       v4l2loopback-ctl set-caps <device> <caps>
       v4l2loopback-ctl get-caps <device>
       v4l2loopback-ctl set-timeout-image [OPTIONS] <device> <image>

DESCRIPTION

       Manage v4l2 loopback devices.

       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.

OPTIONS

       -h, -?, --help: print this help and exit

       -v, --version: print version and exit

VERBS AND THEIR ARGUMENTS

   v4l2loopback-ctl add [OPTIONS] [<outputdevice> [<capturedevice>]]:
              create/add a new loopback-device

       -b <num>, --buffers <num>
              buffers to queue

       -h <h>, --max-height <h>
              maximum allowed frame height

       -n <name>, --name <name>
              pretty name for the device

       -o <num>, --max-openers <num> maximum allowed concurrent openers

       -v, --verbose
              verbose mode (print properties of device after successfully creating it)

       -w <w>, --max-width <w>
              maximum allowed frame width

       -x <x>, --exclusive-caps <x>
              whether to announce OUTPUT/CAPTURE capabilities exclusively

       --min-width <w>
              minimum allowed frame width

       --min-height <w>
              minimum allowed frame height

       -?, --help
              print this help and exit

       <outputdevice>
              if given, create a specific device (otherwise just create a free one).

              either specify a device name (e.g. '/dev/video1') or a device number ('1').

       <capturedevice>
              if given, use separate output & capture devices (otherwise they are the same).

   v4l2loopback-ctl delete <device>:
              delete/remove an unused loopback device

       <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').

   v4l2loopback-ctl list [OPTIONS]:
              list all available loopback-devices

       -e, --escape
              escape control-characters in (device) names

       -h, --help
              print this help and exit

   v4l2loopback-ctl query [OPTIONS] <device>:
              query information about a loopback device

       -e, --escape
              escape control-characters in (device) names

       -h, --help
              print this help and exit

       <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').

   v4l2loopback-ctl set-fps <device> <fps>:
              set the default framerate for a loopback device

       <device>
              either specify a device name (e.g. '/dev/video1') or a device number ('1').

       <fps>  frames per second, either as integer ('30') or fraction ('50/2').

   v4l2loopback-ctl get-fps <device>:
              query the framerate of a loopback device

   v4l2loopback-ctl set-caps <device> <caps>:
              set format/dimension/framerate of a loopback device

       <device>
              either specify a device name (e.g. '/dev/video1') or a device number ('1').

       <caps> format specification as '<fourcc>:<width>x<height>@<fps>' (e.g.  'UYVY:1024x768@60/1')  unset  the
              current caps with the special value 'any'

   v4l2loopback-ctl get-caps <device>:
              get current format/dimension/framerate of a loopback device

   v4l2loopback-ctl set-timeout-image [OPTIONS] <device> <image>:
              set a fallback image to be used if a video producer does not send new frames in time.

       <flags>
              any of the following flags may be present

       -h, --help
              print this help and exit

       -t <timeout>, --timeout <timeout>
              timeout (in ms)

       -v, --verbose
              raise verbosity (print what is being done)

       <device>
              either specify a device name (e.g. '/dev/video1') or a device number ('1').

       <image>
              image file

REPORTING BUGS

       Issue tracker: https://github.com/umlaeute/v4l2loopback/issues
       Security Issue tracker: https://git.iem.at/zmoelnig/v4l2loopback/-/issues

       utils/v4l2loopback-ctl v0.15.0

unable to open control device '/dev/v4l2loopback... June 2025                                          UNABLE(1)