Wayland screenshare script via wf-recorder and v4l2loopback

sharescreen.sh

#!/bin/bash

# Preliminary steps (void linux):
# sudo xbps-install -Su v4l2loopback wf-recorder
# (don't forget to reboot if new Kernel version was upgraded)
#

# Too lazy to autodetect active monitor resolution
WIDTH=2560
HEIGHT=1440


# Detect and load kernel module if needed
lsmod | grep v4l2loopback \
  && echo "Kernel module detected" \
  || ( \
    echo "Need to modprobe v4l2loopback kernel module, please authorize:" \
    && sudo modprobe v4l2loopback \
  )

# List devices and exit when run without args
if [ -z "$1" ]; then
  v4l2-ctl --list-devices
  echo "Please rerun sharescreen with the device device path of the Dummy listed above"
  echo "Ex: sharescreen /dev/video4"
  exit 1
fi

device=$1

# Let device timout to prevent device-busy errors
# v4l2-ctl -d $device -c timeout=3000 # unverified

# Set capabilities for device, so chrom*/webrtcvideocapturer.cc
# based software like discord is happy.
#
# https://gstreamer.freedesktop.org/documentation/video/video-format.html?gi-language=c#GstVideoFormat
# GST_VIDEO_FORMAT_YUY2 (4) – packed 4:2:2 YUV (Y0-U0-Y1-V0 Y2-U2-Y3-V2 Y4 ...)
# Suspicion that matching GST format is `YUY2` is further backed
# by output of `gst-device-monitor-1.0` and finding section of webcam hardware
# that's works in chosen software
v4l2loopback-ctl set-caps \
  "video/x-raw, format=YUY2, width=$WIDTH, height=$HEIGHT" \
  $device || \
  echo "WARN; Failed to set format, rmmmod / modprobe to free device?"

##
# In case your v4l2loopback utility is a different version, from what I can
# dump, the significant commands my version executes is:
#
#   v4l2-ctl -d /dev/video4 -c keep_format=1
#   v4l2-ctl -d /dev/video4 -c sustain_framerate=1
#   gst-launch-1.0 videotestsrc num-buffers=1 '!' video/x-raw,format=YUY2,width=2560,height=1440 '!' v4l2sink device=/dev/video4
#

# Start screen-capture and dump the frames into chosen loopback-devices
wf-recorder --muxer=v4l2 --file=$device \
  -c rawvideo -x yuyv422

Thanks. It works.

cheers