record window on x11 using ffmpeg

record-screen.sh

#!/usr/bin/env bash
NOCOLOR='\e[0m'
RED='\e[0;31m'
GREEN='\e[0;32m'
YELLOW='\e[1;33m'
CYAN='\e[0;36m'
command -v ffmpeg >/dev/null 2>&1 || { echo >&2 "${RED}ffmpeg not installed!${NOCOLOR}"; exit 1; }
echo -e "You can select a window for ${CYAN}fixed coordinates${NOCOLOR} in 3 seconds."
sleep 3
echo "Select window!"
XW="$(xwininfo)"
W=$(echo "${XW}" | grep 'Width:' | sed 's/[^0-9]//g')
H=$(echo "${XW}" | grep 'Height:' | sed 's/[^0-9]//g')
X=$(echo "${XW}" | grep 'Absolute upper-left X:' | sed 's/[^0-9]//g')
Y=$(echo "${XW}" | grep 'Absolute upper-left Y:' | sed 's/[^0-9]//g')
FN=~/Videos/$(date +'%Y%m%d_%H%M%S').mp4
echo -e "${CYAN}Size:${NOCOLOR} ${W}x${H}"
echo -e "${CYAN}Coord:${NOCOLOR} X=${X} Y=${Y}"
echo -e "${CYAN}Output:${NOCOLOR} ${FN}"
echo -e "Starting in ${GREEN}3${NOCOLOR}" && sleep 1
echo -e "Starting in ${YELLOW}2${NOCOLOR}" && sleep 1
echo -e "Starting in ${RED}1${NOCOLOR}" && sleep 1
echo -e "${RED}=============================================${NOCOLOR}"
ffmpeg -f x11grab -s ${W}x${H} -i :0.0+${X},${Y} -r 25 -vcodec libx264 ${FN}
if [ -f "${FN}" ]; then
  echo -e "${GREEN}File saved:${NOCOLOR} $(ls -sh ${FN})"
fi