live green screen solution with ffmpeg and v4l2 pseudo device
In order to get this work you need to have a recent kernel with v4l2 loopback device enabled, and ffmpeg 3.4 or greater with chroma key support. Make sure to check which camera device to use:
v4l2-ctl --list-devices
Then load
sudo apt install v4l2loopback-utils v4l2loopback-dkms ffmpeg
sudo modprobe v4l2loopback video_nr=2 exclusive_caps=1 card_label="green-screen"The exclusive_caps=1 makes it work with chrome browser and google conference, shamelessly lifted from here Thanks figuring this out!
To check if mjpg is supported:
v4l2-ctl --list-formats -d /dev/video3
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture
[0]: 'YUYV' (YUYV 4:2:2)
[1]: 'H264' (H.264, compressed)
[2]: 'MJPG' (Motion-JPEG, compressed)
Download and copy this script into /usr/local/bin then execute with
when background image is specified, the behavior is same is before:
chromakey -i path_to_background_image.png -c /dev/video3 -o /dev/video2
alternatively you can grab an area of the screen:
chromakey -c /dev/video3 -o /dev/video2 -x_pos=0 y_pos=800
steven@io:~/projects/chromakey$ ./chromakey -h
chromakey replaces specified color key with background image of live video
when '--image' is not specified it grabs the screen at '--x_pos' and '--y_pos'
of area specified with '--size'
USAGE: chromakey [arguments]
ARGS:
-h, --help # This help message
-v, --verbose # Enable verbose messages
-k, --key # specify color key (DEFAULT: green)
-m, --similarity # chromakey similarity (DEFAULT: 0.19)
-b, --blend # specify color key (DEFAULT: 0.07)
-s, --size # video stream size in pixels: 1280x720
-i, --image # specify image for background (DEFAULT: )
-c, --camera # the real input camera device path (DEFAULT: /dev/video0)
-o, --output # v4l2 pseudo device (DEFAULT: /dev/video1)
-r, --rate # frame rate (DEFAULT: 30)
-x, --x_pos # xgrab: x position (DEFAULT: 0)
-y, --y_pos # xgrab: y position (DEFAULT: 0)
Copyright (c) <Steven Varga 2010-2021> <[email protected], Toronto, On>
The live chromakey-ed videostream will be available on specified output device, usually /dev/video1 and can be checked with ay v4l2 compatible device
here is firefox:
https://webrtc.github.io/samples/src/content/devices/input-output/
Skype also known to work.