ffmpeg green screen chromakey virtual background for linux

README

setup

1. Install video 4 linux (v4l)  
   
   https://github.com/umlaeute/v4l2loopback
   
2. Install ffmpeg 

   https://linuxize.com/post/how-to-install-ffmpeg-on-ubuntu-18-04/
   
3. Make camera cap exlusive (otherwise Chrome cant access the vcam video

   sudo modprobe v4l2loopback -r && sudo modprobe v4l2loopback video_nr=4 exclusive_caps=1 card_label="vcam"
   
4. Enable access by chrome, zoom etc. user apps

   chmod 660 /dev/video4

vcam.sh

#!/bin/bash

IMAGE=${1:-$HOME/Pictures/camback_640480.png}
FRAME_RATE=35
CAMERA=/dev/video2
OUTPUT=/dev/video4
SIZE=640x480
# make sure access is granted to user processes, e.g. chrome, zoom
sudo modprobe v4l2loopback -r 
sudo modprobe v4l2loopback devices=1 video_nr=4 exclusive_caps=1 card_label="vcam"
sudo chmod 660 $OUTPUT
ffmpeg -thread_queue_size $FRAME_RATE -filter_complex_threads $FRAME_RATE -y -hide_banner -i $IMAGE \
   -f v4l2 -pix_fmt mjpeg -framerate $FRAME_RATE -video_size $SIZE -i $CAMERA -input_format mjpeg \
   -filter_complex "[1:v]chromakey=green:0.16:0.0[raw];[raw]crop=in_w-200:in_h:200:200[ckout];[0:v][ckout]overlay=200:000[out]" \
   -map "[out]" \
   -pix_fmt yuyv422  \
   -f v4l2 $OUTPUT


# installation:
# sudo apt-get install v4l2loopback-dkms
# sudo apt install ffmpeg
# sudo apt install v4l-utils

This is the Linux equivalent of a Zoom Virtual Background. Works with Chrome, Meetup, Skype et al

Why? Meetup and Skype don't have virtual backgrounds on Linux. Zoom does. This makes it available verywhere.
Caveats? Framerate is relatively slow. Could only get it to about 25fps. If you have any idea let me know

Thanks to Steven Varga, who inspired me to try ffmpeg. His solution is more convenient, however it uses a different filter setup that did not work for me. https://github.com/steven-varga/chromakey