I want to send video to webcam device on Ubuntu which is loaded on /dev/video0

I've already seen this command that send desktop to it but is there any way to send video to it?

ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0

I should mention that i specifically want to use ffmpeg command.

  • It's my understanding that a webcam is an video input device so I would say no. What webcam do you have that supports receiving video? – Elder Geek Feb 8 '17 at 19:12
  • @ElderGeek there is no webcam.it is virtual one which need to have video on it. – dsddd Feb 8 '17 at 19:15
  • HAve you tried using a pipe? – Elder Geek Feb 8 '17 at 19:25
  • Information is available here – Elder Geek Feb 8 '17 at 19:29
  • 1
    Possible duplicate of Fake a webcam using a video loopback device? (although not necessarily using ffmpeg). – llogan Feb 8 '17 at 19:39

You can do this with v4l2loopback. First you need to install it:

Install v4l2loopback

Method 1: Install v4l2loopback from the repository

sudo apt install v4l2loopback-dkms
sudo modprobe v4l2loopback

This is easy but older versions of v4l2loopback have some known bugs, so consider compiling it instead if you encounter any issues.

Method 2: Compile v4l2loopback

If it's not in the repository for your Ubuntu version, or you want the latest version, you can compile it:

sudo apt-get install build-essential checkinstall
wget https://github.com/umlaeute/v4l2loopback/archive/master.zip
unzip master.zip
cd v4l2loopback-master
sudo checkinstall --pkgname=v4l2loopback --pkgversion="$(date +%Y%m%d%H%M)-git" --default
sudo modprobe v4l2loopback


If you want to remove the package you compiled:

sudo apt-get remove v4l2loopback

Usage examples

Now run ffmpeg. Example for desktop using x11grab:

ffmpeg -f x11grab -framerate 15 -video_size 1280x720 -i :0.0 -f v4l2 /dev/video0

Example for a video input:

ffmpeg -re -i input.mp4 -map 0:v -f v4l2 /dev/video0

You can view it with ffplay:

ffplay /dev/video0

Note that the actual video number may vary depending if an existing device is already using /dev/video0.

| improve this answer | |
  • where can i specify my video ? – dsddd Feb 8 '17 at 21:08
  • @dsddd Example updated. – llogan Feb 8 '17 at 21:13
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    I installed the package, but I'm stuck with an error on both examples, either the x11grab or the the mp4 video give me the same [v4l2 @ 0x55ebc0cfdc40] ioctl(VIDIOC_G_FMT): Invalid argument Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument Error initializing output stream 0:0 -- Conversion failed! Is there something else I should do? some dependencies I missed? – Sabbin Jan 29 '19 at 16:43
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    @llogan following your example above, I have this command ffmpeg -re -i 1.mp4 -map 0:v -f v4l2 /dev/video0 pastebin.com/9eDK0NTN, if I try the command to run for desktop ffmpeg -f x11grab -framerate 15 -video_size 1280x720 -i :1 -f v4l2 /dev/video0 I get this error pastebin.com/xN6uZJR6, also the folder /dev/video0 has rights for write – Sabbin Feb 4 '19 at 7:37
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    @sabbin try with /dev/video1 – Chicken Soup Jul 3 '19 at 10:45

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