Questions tagged [v4l2]
The v4l2 tag has no usage guidance.
57
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FFmpeg Record videos every second and save them in individual files
I am trying to create video every one second. I have the following code below.
It creates the first video correctly but the following does not create them correctly. Anyone know what I may be missing, ...
0
votes
1
answer
25
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How could I run this process (v4l2rtspserver) in the background?
I am trying to run on Debian system (Dietpi on Raspberry Pi):
v4l2rtspserver -H 1080 -W 1920 -F 30 -P 8555 /dev/video0
But it keeps running in the command console despite adding & disown
I have ...
- 139
1
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0
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39
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How to trim a stream from an rtsp camera with ffmpeg?
I need to crop the image of a stream coming from a camera on a Raspberry pi.
The camera is placed in a door peephole and I need to crop and enlarge the area of interest to see it full screen.
I have ...
- 139
1
vote
1
answer
30
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Synchronize recording of three cameras with ffmpeg
I am trying to make the video that is recorded from three usb webcams be synchronized, I am using this command, but I still have differences by milliseconds or seconds. Any idea how to achieve it?
...
2
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0
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39
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Strange video distortion capturing video from GV-USB2 on Linux using FFMPEG
I'm trying to capture video from a GV-USB2 (a popular composite/S-Video capture card) on a Raspberry Pi 4B running Raspbian Buster. I built and installed these V4L2 drivers for the GV-USB2, and when I ...
- 121
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292
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Force a webcam to use a specific resolution
I want to force a webcam to only use a specific resolution.
Discord and facebook etc seem to default to maximum resolution, and I want to stop this behaviour in preference to lower resolution and ...
- 21
0
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1
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383
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Trying to emulate a hardware camera with a stream from a raspberry pi/picam?
I have a raspberry pi and pi cam v2 connected to wifi. I am trying to stream the camera feed to a laptop over wifi, then make that stream appear as if it were a hardware camera on the laptop. I want ...
- 1
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1
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162
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Can't play video file to virtual camera and then webcam to virtual camera v4l2
When I try to play a video to a virtual camera it works
but when I try to play webcam to virtual camera it doesn't do anything.
What I do:
Playing video to virtual camera:
ffmpeg -re -i "yt.mkv&...
- 11
0
votes
1
answer
208
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Howto redirect cheese webcam effect to new video device
I am on ubuntu 20.04, but v4l2 package is not working: so I installed it from here
git clone git@github.com:umlaeute/v4l2loopback
make
sudo insmod v4l2loopback.ko exclusive_caps=1 video_nr=1 ...
- 101
1
vote
1
answer
1k
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MJPEG stream from webcam not working
I have 5 HD Webcams (Creative Live Cam Sync 1080p) and want to stream the pictures with https://github.com/jacksonliam/mjpg-streamer on Debian Buster 4.19.0-11-amd64.
All of them support MJPG, as you ...
0
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1
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809
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V4L2 Loopback: VLC can use it, but a web browser can't
I have a bunch of USB 3 capture devices feeding OBS, and V4L2 Loopback to provide OBS's output as another video input. (/dev/video99) I want to use that output in an online meeting, but neither ...
- 181
1
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0
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119
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FFmpeg/FFplay sometimes goes to sleep waiting on IO when webcam is unplugged
I made a webcam viewer out of a Raspberry Pi with Raspbian, FFmpeg/FFplay, and v4l2. I have a udev rule that automatically starts an FFmpeg stream and brings up FFplay to view it when my webcam is ...
- 11
0
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1
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22
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Simultaneusly connecting several webcams
I have 4 webcams, plugged into a USB hub, that I would like to use with my computer. I can find out which devices are recognized by the computer with v4l2-ctl --list-devices. When I plug the entire ...
0
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1
answer
314
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Rename Devices in V4L2?
I have 4 identical HDMI -> USB 3 capture devices, meant to feed a live broadcast. That works just fine. After some one-time trial-and-error on the initial install, the broadcast production ...
- 181
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1
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548
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How do I stream JPGs to v4l2loopback with ffmpeg?
I'm trying to use ffmpeg to stream images into v4l2loopback, but it seems like only pngs work. Here's the command that I am using, where <image> is the path to an image, and /dev/video63 is a ...
- 103
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0
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1k
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FFmpeg: synchronize streams from two webcams
Making an MP4 file with two video streams, each from a different webcam, like this:
ffmpeg -f v4l2 -thread_queue_size 32 -video_size 1920x1080 -input_format mjpeg -i /dev/video6 \
-f v4l2 -...
- 208
0
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1
answer
2k
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Stream linux destop as fake webcam to virtuabox windows guest
I would like to capture (a part of) my linux desktop (ubuntu 20.04), stream it as a webcam to a windows 10 guest VM running in Virtualbox.
I found Using desktop as fake webcam on linux which got me ...
- 111
0
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1
answer
475
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Green tinted flickering screen with FFmpeg + v4l2loopback-dkms
I have a Raspberry PI 4 with a Raspberry 7" touch screen, where buster is installed with Ffmpeg, Gstreamer, and v4l2loopback-dkms.
To that I have attached a USB video grabber dongle, where I have ...
- 11
2
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0
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1k
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FFmpeg output sent to v4l2loopback video device won't be read by guvcview
I set a dummy camera /dev/video1 with v4l2loopback module.
I can read the stream with ffplay, vlc or even zoom of this camera when I send to it contentwith ffmpeg:
ffmpeg -re -i input-file.mp4 -f v4l2 ...
- 233
0
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1
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262
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virtual webcam from dvcam input on firewire - linux
I'd like to use my dvcam as a webcam on linux (ubuntu 18.04). It works happily under windows showing up as a video source.. but on linux not so easy.
It shows up on /dev/fw0 & fw1 as 720x576 ...
- 113
0
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1
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902
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Realtime overlay png image (with tansparency) over webcam output to feed to v4L2 loopback virtual video camera
I've been struggling with this for a few days and just can't get the final part of the FFmpeg command right. I'd be very grateful for any help please. I have studied similar questions and answers on ...
- 101
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0
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2k
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"Non-monotonous DTS in output stream" when capturing video with ffmpeg
I'm trying to capture VHS video on Linux using a new USB capture device and FFMPEG.
I'm able to successfully capture either only audio (using Alsa), or only video (using v4l2) but when I try to do ...
- 31
1
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2
answers
2k
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Linux USB video capture issues
I purchased the Hauppauge USB-Live 2 capture device because several recent Amazon reviews suggest it should work with modern Linux kernels.
When I plug it into my Raspberry Pi 4 running the latest ...
- 31
1
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0
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97
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Synchronize multiple realtime inputs
I'm trying to record a video+audio using ffmpeg from 3 sources: x11grab (desktop), v4l2 (webcam) and alsa (microphone). I'm using this script:
#!/bin/bash
set -x
out=$1
rm -vf $out
rate=25
cam_size=...
- 133
0
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1
answer
290
views
Merge x11grab with v4l2 into single output file
I'm trying to record a video using ffmpeg from two inputs: webcam (v4l2) and desktop (x11grab). I checked that both inputs are working fine:
ffmpeg \
-f x11grab -s 1920x1080 -r 25 -i :0.0 \
-...
- 133
1
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1
answer
2k
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gstreamer using h264 encoding with small video size
I need to record a video using my usb webcam in my linux based pc. I found gstreamer with h264 encoding for lower the cpu percentage.
But i am new to gstreamer so i had errors when running some ...
- 115
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1
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612
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Piping mp4 video file to v4l2 devices lowers the frame rate in ffmpeg
I'm trying to play a 10fps video file on multiple v4l2 loopback devices.
Although the following command outputs the video on the video devices, it does not maintain the framerate. The framerate (and ...
- 69
0
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1
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356
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Gstreaming - two web cams over tcp
I'm trying to stream two web cams on a single gstreaming command, I'm able to start a single camera with :
gst-launch-1.0 v4l2src device=/dev/video0 ! videoconvert ! videoscale ! video/x-raw,width=...
- 101
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0
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2k
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V4L2 doesn't use a lower advertised frame rate
I'm capturing images on Linux (Pi 3B+, Stretch lite). The camera reports that it's capable of delivering images at 30 fps or 60 fps. Here's the output from v4l2-ctl
v4l2-ctl --list-formats-ext
ioctl: ...
- 123
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0
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1k
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How to inform vlc for sample rate change from device in linux
I'm working in FPGA device, which can provide raw video and pcm data. I'm using v4l2 and alsa framework for video and audio respectively. Audio flow path is using ALSA framework and video flow path is ...
3
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0
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1k
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What is the right ffmpeg output format for playing a video to webcam using v4l2-loopback in linux? [duplicate]
please can someone show me the new syntax for sending videos to webcam using ffmpeg and v4l2loopback?
It used to work perfectly until I updated and upgraded recently
the previous syntax i use is:
...
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5
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1
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24k
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What is the right ffmpeg output format for a v4l2-loopback device?
Following the guide in this question I did:
$ sudo modprobe v4l2loopback
$ ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0
The device ...
3
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0
answers
4k
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ffmpeg stream video file to fake webcam
I'm trying to set up ffmpeg to forward video stream from file to dummy video device created by v4l2loopback
My command looks like following:
ffmpeg -re -i video.mp4 -c:v rawvideo -pix_fmt yuv420p -f ...
- 131
0
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1
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102
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Identify kernel module for analogue video capture card Multimedia video controller: Adaptec (formerly DPT) Device 9065
I'm trying to identify a kernel module to make an analogue video capture card work on video4linux.
lspci:
Multimedia video controller: Adaptec (formerly DPT) Device 9065
02:04.0 Class 0400: Device ...
1
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0
answers
280
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EM2860 based video converter captures corrupted frames (how to debug?)
I designed my own analog video to USB converter. This converter is based on the TI TVP5150AM and the Empia EM2860. Shortly the converter works as shown in the diagram below.
+---------+ ITU-...
0
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1
answer
2k
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Compile Linux V4L-DVB media_build for a specific kernel (not the running one)
Is it possible to compile the LinuxTV.org V4L-DVB media_build for a kernel source contained in a specific path, instead of the running one (i.e. a different version)?
I have the kernel sources and in ...
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2
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6k
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v4l2 Identifying /dev/video* via lsusb
I'm writing a script that must use a particular camera plugged in to my system.
$ lsusb|grep C930e
Bus 001 Device 011: ID 046d:0843 Logitech, Inc. Webcam C930e
How can one programatically discover ...
- 139
3
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1
answer
7k
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FFmpeg build with V4L2
I want to use ffmpeg to access my webcam. I tried:
ffmpeg -f v4l2 -i /dev/video0 output.mp4
but I am getting an error:
Unknown input format: 'v4l2'
Similarly with video4linux2 instead of v4l2. I ...
- 257
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1
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1k
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No such input format: MJPEG
I want to convert my camera pixels format from YUYV to MJPEG. I tried to use v4l-utils but when i used this commend in terminal:
ffmpeg -f video4linux2 -pixel_format MJPEG -i /dev/video0
but when I ...
- 103
4
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0
answers
8k
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How to know which framerate should I use to capture webcam with ffmpeg?
I'm capturing video from my webcam with the following command:
ffmpeg -r 30 -f v4l2 -video_size 160x120 -i /dev/video0 output.avi
The -r option indicate the framerate I want. However, it's not that ...
- 141
11
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3
answers
11k
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Can I use my DSLR as webcam through gphoto2 + v4l2loopback?
So, what i'm trying to do may be a little complicated, by i'm finding my way.
Let me explain the basics:
1 - I have an DSLR camera and i want to use it as webcam (but v4l2 can't make a /dev/videoX ...
- 251
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570
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Video for Linux (V4L) generator driver
I would like to experiment with tvheadend but prior to investing in an actual capture card I was wondering if V4L supports a "generate" capture "card" that can just offer video stream of an image or ...
2
votes
1
answer
3k
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Alternatives to Video4Linux2 for grabbing from webcam (Using FFmpeg)
I'm getting (two alternating) errors following this guide for streaming from a Raspberry Pi. Are there any other grabbers besides V4L2 that I can use with ffmpeg?
Or are there any other streaming ...
- 421
2
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0
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1k
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Analog Tv Tuner drivers for ubuntu
I was searching for the Analog usb (stick) tv tuner card for Ubuntu, but I have not found single such tv tuner card with ubuntu drivers available. I tried to search for the open source tv tuner ...
- 131
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3
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5k
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v4l2 issues with webcam encoded to H.264
I am trying to send a H.264 webcam video feed over wifi to another computer using gstreamer. I am using this tutorial as a guide. I am using a Creative Live! Cam Connect HD as my webcam. The website ...
- 11
2
votes
1
answer
3k
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No permission to access webcam on linux
I am using a raspberry pi with raspbian to capture webcam shots and upload them to a web server. However, when I rebooted just now I no longer have access to the webcam. I have no idea why this ...
- 121
2
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2
answers
3k
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How Video4Linux and ALSA work with Codecs
My understanding is that a codec is both a decoder and a specification for decoding. So some group writes a codec which explains how to decode from their format back into the raw bitstream, and they ...
- 2,682
2
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1
answer
376
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V4L2 and ALSA: Kernel SPI or User API?
I'm trying to understand what Video for linux and ALSA are (exactly), and I can't discern whether they're APIs for Linux application to use (the userspace) or if they are backend services that are ...
- 2,682
20
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2
answers
58k
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ffmpeg open webcam using YUYV but i want MJPEG
I need ffmpeg to open webcam (Logitech C910) in MJPEG mode, because the webcam can give ~24 fps using the MJPEG "protocol" and only ~10 fps using the YUYV. Can I choose between them using ...
- 386
0
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1
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2k
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Devices renamed with udev not working, original device node still there
I'm trying to rename certain video devices using udev. Here's a rule (broken down for readability):
ACTION=="add", SUBSYSTEM=="usb", ATTR{busnum}=="1",
ATTR{devpath}=="2", ATTR{idVendor}=="05e1", ...
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