Questions tagged [v4l2loopback]

v4l2loopback is a linux kernel module to create virtual video devices.

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Issues compiling V4L2loopback on raspberry pi bookworm

I installed the latest version of raspios, here is the uname -a Linux raspberrypi 6.1.21+ #1642 Mon Apr 3 17:19:14 BST 2023 armv6l GNU/Linux I git cloned V4l2loopback and tried compiling after ...
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Replacing Phone Internal Camera with Video Footage using v4l2loopback

I'm currently exploring the possibility of replacing my phone's internal camera feed with video footage using v4l2loopback. My goal is to have applications on my phone use a predefined video as if it ...
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Chromium cannot read camera: Dequeued v4l2 buffer contains invalid length #561

I installed the v4l2loopback kernel module on my machine and enabled it with sudo modprobe v4l2loopback exclusive_caps=1. I created a camera on /dev/video0 with the rust bindings and started piping a ...
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Is it possible to have consumer running without producer attached?

I'm playing around with v4l2loopback and I'm trying to have a gstreamer consumer run with the default timeout image when there is no producer but it's failing. How the v4l2loopback device is setup: ...
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High CPU usage from ffmpeg decoding rtsp to v4l2loopback

I got a orangepi5 that has hardware decoders for h264,hevc and other formats. I am using armibian Armbian 23.5.5 Jammy CLI kernel legacy 5.10.160. I've installed a custom ffmpeg that uses RockChip MPP ...
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How v4l2loopback makes a previously ignored udev rule work?

I've found the "how", but am curious about "why". I've got an udev rule for a Sony camera that didn't work: SUBSYSTEMS=="usb", ATTRS{idVendor}=="054c", ATTRS{...
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Internal Data Stream Error Reading v4l2 Virtual Cameras with Gstreamer Pipeline

I'm using v4l2loopback to create 2 virtual cameras that I can then stream an mp4 into and simultaneously read from those cameras with a gstreamer pipeline as if the mp4 was the video being recorded by ...
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V4L2 devices show up in in pipewire. How do I remove them?

Demonstrative image I have every video device duplicated in PipeWire due to v4l2. I cannot recall what I did years ago to make them appear. How can I remove these duplicate devices?
Managor's user avatar
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v4l2loopback-ctl version on debian packages

I would like to use v4l2loopback on a debian (Bookworm) machine. I've installed v4l2loopback-utils package (version 0.12.7-2) but when i run v4l2loopback-ctl --version the result is 0.6. I need to use ...
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Using nvv4l2camerasrc to get data from a virtual device created by v4l2loopback

Is there a way to use nvv4l2camerasrc to get data stream from a virtual device created by v4l2loopback ? Up to now, I just could stream video from a virtual device by following those steps: Create a ...
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Elgato Facecam & v4l2 vertical/horizontal flip

Question for somebody who owns this Elgato webcam model. Does it support vflip and hflip using v4l2?
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Virtual Camera on OBS is Fliped

When I use the Virtual Camera on OBS with v4l2loopback it is flipping the video in the x-axis. Is there a way to reverse it back to normal?
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Can "v4l2loopback" be installed/compiled for FreeBSD 13.1?

Wondering if anyone was able to compile v4l2loopback for FreeBSD 13.1 If so what are the steps. I need it for FFMPEG to convert a live USB cam MJPEG video stream from yuv422 to yuv420 on the fly and ...
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Compiling v4l2loopback on raspberry pi seems to work, but kernel module won't load

After following the steps in order to compile v4l2loopback as shown here: https://www.arducam.com/docs/cameras-for-raspberry-pi/pivariety/how-to-access-and-program-the-pivariety-camera-using-command-...
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Make install puts module in wrong kernel version directory

sudo make install make -C /lib/modules/`uname -r`/build M=/home/pi/v4l2loopback modules_install make[1]: Entering directory '/home/pi/5.15.32-v8+/linux-60652604154e70aeac81fb6155fd9d15dc39daaf' ...
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How can I create a virtual microphone device?

I use OBS to stream into Google Meet so I can send music and a opening scene. I also use OBS option for create a virtual camera, once I use a DSRL camera and not a webcam. The issue I need to solve ...
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v4l2loopback /dev/video2 Not being created

Running: Arch Linux, using package "v4l2loopback-dkms" Software I'm trying to get running: https://github.com/fangfufu/Linux-Fake-Background-Webcam This software uses v4l2loopback, which I'...
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Use v4l2loopback in docker, /dev/video0 missing in docker

I have installed v4l2loopback in the docker container using the following commands apt update apt install -y apt-utils apt install sudo sudo su root - apt-get install -y module-assistant m-a prepare m-...
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How to receive "v4l2-ctl --stream-to-host" stream from a machine on the same LAN on said host for use with, e.g., video conferencing software?

There is an example that streams a webcam to another computer by piping a V4L2 stream into netcat (v4l2-ctl --stream-to - | nc <host> <port>), and this works, but it feels redundant when ...
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OBS Studio Virtual Camera and Iriun seem to be in Conflict

I am running Ubuntu 20.04 LTS Desktop. I have installed OBS Studio and Iriun. Both work fine as long as I don't try to use the Virtual Camera from OBS. When I do, the Iriun screen turns a pixalated ...
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v4l2-loopback only works once, can't stop and start again

I am using v4l2-loopback to create a virtual webcam that can be recognized by Chrome. The first time I start the loopback after rebooting everything works, but when I kill the loopback for the first ...
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how many max loopbacks can i have?

How many loopbacks are possible with v4l2loopback-dkms? Can i only have 8 loopbacks using modprobe v4l2lookback devices=8, any more and it seems to be capped at 8.
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Problem with make when building v4l2loopback

I'm trying to build v4l2loopback by simply entering: make Building v4l2-loopback driver... make -C /lib/modules/`uname -r`/build M=/home/user/dev/labs/v4l2loopback modules make[1]: Entering ...
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black screen when trying to loopback desktop with v4l2loopback in proxmox guest VM

Background i'm currently trying to setup an Android Emulator for WhatsApp bridging with my Matrix-Server. I followed the instructions here up to the point where i have to setup a webcam for the QR-...
Michael's user avatar
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Error building v4l2-loopback driver on pi400

I'm trying to turn my phone webcam into a "fake webcam" for my raspberry pi 400, but I get an error: Anas@raspberrypi:~/Downloads/server/v4l2loopback $ make Building v4l2-loopback driver... ...
Anas Kattan Khayta's user avatar
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v4l2loopback installation. Not working on 5.14 kernel

Running the 5.14.1 kernel. Tried using this repo to install v4l2loopback by compiling and installing(make; make install). It reported success. As per this recommendation, installed the 5.14.1 headers ...
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Webcam stopped working after updating Arch Linux

I updated 2 days ago and my webcam stopped working. The following softwares do not detect my built-in webcam: Zoom Discord Chromium /dev/video is not present. /dev/video0 is not present. The camera ...
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Mirrorless camera as webcam - Sony A5100 & ElGato Camlink 4K

I am trying to get my Sony A5100 working as a webcam on Linux, specifically Fedora 32 on the 5.11.22-100.fc32.x86_64 kernel. Likely time to upgrade, but I figured I'd query here a bit first to see if ...
ThoseKind's user avatar
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How to know if the kernel is compatible with v4l2loopback?

I want to use v4l2loopback to stream from OBS-Studio in Microsoft Teams or discord, but I'm not sure if it will work with my system (I also don't really understand the section "DEPENDENCIES" ...
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RuntimeError: 'v4l2loopback' backend: std::exception

I'm getting above error when I'm trying to execute following piece of code: import pyvirtualcam import numpy as np with pyvirtualcam.Camera(width=1280, height=720, fps=20) as cam: print(f'Using ...
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v4l2 loopback working fine with openCV but weird output on OBS

I'm as CS student and i'm trying to make a project where I output my webcam video flow but as an ascii art. In order to do so, I get the image from v4l2. then i use OpenCV to decode the image (i wasn'...
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After having updated Fedora, v4l2loopback does not work anymore

After having upgraded from Fedora 33 to Fedora 34, it seems that v4l2loopback does not work anymore. I did install v4l2loopback-dkms from https://copr.fedorainfracloud.org/coprs/sentry/v4l2loopback/ ...
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Replicating v4l2loopback command in OSX Big Sur?

I'm trying to replicate the following command in OSX: sudo modprobe v4l2loopback video_nr=3 card_label="TestVideo" So far I've tested the following advice here but I keep getting an error ...
Kirk Walla's user avatar
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2k views

v4l2loopback: Virtual camera exists, but doesn't show up in Zoom, and doesn't work in Cheese

I have successfully set up the virtual camera in OBS: sudo apt install obs-studio v4l2loopback-dkms sudo usermod -aG video myuser The following versions are installed: v4l2loopback-dkms 0.12.5-1 obs-...
knipknap's user avatar
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how do I set properties of a v4l2loopback device and make them visible to my web browser?

I've created a couple of v4l2loopback devices for use as virtual webcams, and have been able to get Chrome to recognize them via navigator.mediaDevices.enumerateDevices(). I've also been able to ...
Dan O's user avatar
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1 answer
7k views

How to best install v4l2loopback on Linux Mint?

I am trying to create a virtual webcam from OBS(26.1.1) so I can feed it to Zoom. I am Linux Mint 20.1 Cinnamon, version 4.8.6, Kernel 5.4.0-64-generic. I did: sudo apt-get install v4l2loopback-dkms ...
Karl Berggren's user avatar
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How can a producer detect if a consumer is attached?

I'm using v4l2loopback plus a program I wrote to produce a virtual camera stream. Right now, I start and stop my program by hand when it's needed. I'd rather have it run as a daemon always, and only ...
Piquan's user avatar
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High latency on v4l2loopback

How do I combat the audio delay / latency here? https://s.natalian.org/2021-01-02/sync.mp4 I'm using a GH5 connected to my T14s running Archlinux with /lib/modules/5.10.3-arch1-1/extra/v4l2loopback.ko....
hendry's user avatar
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v4l2loopback-ctl set-fps or set-caps results in errors like can't parse or /sys/devices/virtual/video4linux no such file or directory?

Possibly pertinent information: Ubuntu 20.04, Logitech 1080p USB Webcam, NVidia GTX 1080 I installed v4l2loopback and I got it working using one solution out there but it required that I specify /dev/...
Nathan McKaskle's user avatar
2 votes
1 answer
21k views

modprobe: FATAL: Module v4l2loopback not found in directory

I run a debian 10 with kernel 5.9.0.0 I installed v4l2loopback from the official repo, as in sudo apt install v4l2*, which installed sudo apt install v4l2* Reading package lists... Done Building ...
arteteco's user avatar
4 votes
1 answer
2k views

v4l2loopback devices not showing in applications

I have been successfully using v4l2loopback, with v4l2sink in OBS, to "send" my obs preview panel output to Zoom. The v4l2loopback devices have recently stopped showing in Zoom, Firefox &...
Gaynor Cosgrove's user avatar
1 vote
1 answer
2k views

How do I change the resolution/capabilities of a v4l2loopback device on the fly?

I'm trying to switch from one advertised resolution/framerate to a different one on the fly, preferably while other applications are consuming the v4l2loopback feed. As an example, I feed a 1920x1080 ...
b12f's user avatar
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2 votes
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ffmpeg v4l2 driver changes framerate of Logitech c920 camera

I own a Logitech c920 camera which seems to be able to do at least 24fps for 1080p (although the specs say it should go up to 60), according to vlc -vvv --color v4l2:///dev/video0 --run-time 1 vlc://...
Paulo Matos's user avatar
2 votes
1 answer
113 views

Why are my colors separated/shifted when using obs/v4l2sink/v4l2loopback?

Im using OBS with v4l2sink and v4l2loopback to edit my video for a remote trainig. The preview in obs looks fine, but the video has some serious color shifts in any tool I try to display the ...
hd42's user avatar
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12 votes
1 answer
3k views

Why can multiple consumers access a *single* v4l2-loopback stream from a webcam

I recently needed a single webcam to be shared simultaneously by 3 applications (a web browser, a videoconferencing app, and ffmpeg to save the stream). It's not possible to simply share the /dev/...
justyn's user avatar
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5 votes
1 answer
7k views

How to create a v4l2 device that is a cropped version of a webcam?

I have a Logitech Webcam C930e on /dev/video0. I can use this for doing video conferences (e.g. jitsi). However, the video from this webcam is too high and too broad. I would like to have a "cropped" ...
Markus's user avatar
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8 votes
2 answers
22k views

Adding and removing v4l2-loopback devices?

I have different lxc containers running on my machine and a webcam is also attached. I want all of the lxc containers to access this camera. I came across 'v4l2-loopback' devices and found a way to ...
beenum's user avatar
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8 votes
1 answer
11k views

How to create dummy webcam?

I would like to join some videoconference, but I don't own a webcam and the conference software requires one. So my question is, can I create a dummy one? I don't care what the cam will cast, I just ...
Pitel's user avatar
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