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Questions tagged [v4l]

Video4Linux is the linux kernel video capture subsystem, with a set of userland utilities.

For more information: http://www.linuxtv.org/projects.php

57 questions
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How do I find out which process is using my V4L2 webcam?

I tried to run the following: $ vlc -I dummy v4l2:///dev/video0 --video-filter scene --no-audio --scene-path webcam.png --scene-prefix image_prefix --scene-format png vlc://quit --run-time=1 VLC…
Turion
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16
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2 answers

Understanding webcam 's Linux device drivers

As far as I know, device driver is a part of SW that is able to communicate with a particular type of device that is attached to a computer. In case of a USB webcam, the responsible driver is UVC that supports any UVC compliant device. This means…
dempap
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11
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1 answer

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/video* stream because as soon as one application is…
justyn
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8
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2 answers

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 add devices using; modprobe v4l2loopback…
beenum
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8
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1 answer

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 need to appear to have one.
Pitel
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5
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1 answer

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" version of /dev/video0 that does not show the…
Markus
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4
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1 answer

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 & Brave. However, I can confirm the loopback is viewable in…
Gaynor Cosgrove
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Use guvcview to setup Logitech C920 webcam and keep configuration

I have a Logitech C920 webcam connected to my computer running Debian Linux. I want to access the stream by using mplayer (/dev/video0) and it works out of the box. However, the saturation/brightness/other settings are not correct, so I use guvcview…
Jonathan M
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4
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2 answers

Chroma key (green screen) live for a webcam?

Is there a way to apply chroma key live to a stream that's used in video conferencing. Webcam works fine though v4l (Cheese, Ekiga). This but in Linux.
user89897
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4
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How to record v4l webcam with ffmpeg? Cannot find a proper format for codec 'none'

Goal is to capture video from my old usb webcam (device 0733:0430). Trying to save video gives this error. (I've tried both ffmpeg and avconv.) Command ffmpeg -f v4l2 -i /dev/video2 -s 160x120 tmp.mkv [video4linux2,v4l2 @ 0x815280] Time per frame…
Rucent88
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3
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1 answer

Capture raw image from V4L (webcam) device

I'm using a Raspberry pi to monitor a self-service fridge. When the door opens, a shell script is being executed to capture pictures until the door closes again. The problem, however, is the speed of the ARM-processor. Capturing in full resolution…
Finwood
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3
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2 answers

Set output framerate of a v4l2 device

I am using v4l2loopback v0.12.5 and wf-recorder to record my screen on wayland. I am looking to reduce the framerate of the video stream as read by my browser. Currently I am unable to get anything other than 60fps. I have used version wf-recorder…
Charlie Egan
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3
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When i plug in usb camera i get 2 devices

When I plug in the camera to Linux then I get 2 devices /dev/video0 and /dev/video1 Why is that happens and is that normal? Odd numbered devices do not work. /dev/v4l/by-path looks like that: lrwxrwxrwx 1 root root 12 dets 15 01:29…
Paxmees
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3
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Understanding media-ctl output

I am working with a Dragonboard410c and I am trying to using a gstreamer pipeline to generate an mp4 video from a Logitech C270 USB camera. For this task I am following the instructions reported here at the section Using CSI camera, which are…
xyx
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3
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1 answer

release/close capture of camera

I have opened webcam for capturing using OpenCV in C++. Then I stopped the program using CTRL+Z; The webcam could not turn off, Because was not defined in program. And I can not start my program again because the capture program is still using…
Mohammad Etemaddar
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