O que isso aqui faz?

#!/bin/bash
#clear
#echo -e '\033[01;32mABCDEFGHIJKLMNOPQRS\033[00;0m'
echo -e '\033[01;32m—— KWAICUTTER v3 ——\033[00;0m'
echo -e "\033[01;32m———————————————————\033[00;0m"
folder=$(pwd)
tl="temp_log.txt"
video=$(ls -t "$folder" | grep '.mp4' | head -1)
image=$(ls -t "$folder" | grep '.png' | head -1)
#echo -e "\033[01;32mRECURSOS DETECTADOS\033[00;0m
echo "" > $tl
echo -e "\033[01;32mVídeo:\033[00;0m $video" | tee -a $tl
echo -e "\033[01;32mFundo:\033[00;0m $image" | tee -a $tl
now=$(date +"%d-%m-%Y_%H-%M-%S") ; echo $now >> $tl
outputfile="corte_$now.mp4"
if [[ "$@" == *"-c"* ]]; then
echo -e "\033[01;32m———————————————————\033[00;0m"
    echo -e -n "\033[01;32mInício [Ex 00:00:10]: \033[00;0m"; read start ; echo "começo: $start" >> $tl
    echo -e -n "\033[01;32mFinal  [Ex 00:01:30]: \033[00;0m" ; read end ; echo "the end: $end" >> $tl
else
    start="00:00:00"
    end=$(ffmpeg -i "$video" 2>&1 | grep "Duration" | cut -d ' ' -f 4 | sed s/,//)
fi
echo -e "\033[01;32m———————————————————\033[00;0m"
echo -e "\033[01;32mTítulo:\033[00;0m"
read -r 'line1'
read -r 'line2'
echo -e "\033[01;32mSubtítulo:\033[00;0m"
read -r 'line3'
read -r 'line4'
line1=$(echo $line1 | sed "s/'/\'\\\\\\\\\\\\''/g")
line2=$(echo $line2 | sed "s/'/\'\\\\\\\\\\\\''/g")
line3=$(echo $line3 | sed "s/'/\'\\\\\\\\\\\\''/g")
line4=$(echo $line4 | sed "s/'/\'\\\\\\\\\\\\''/g")
while true; do
	echo -e "\033[01;32m———————————————————\033[00;0m"
    echo -e -n "\033[01;33mRenderizar? (s/n) \033[00;0m" ; read answer
    if [ "$answer" == "s" ]; then
        break
    elif [ "$answer" == "n" ]; then
        exit
    else
        echo -e "\033[01;31mApenas 's' ou 'n'\033[00;0m"
    fi
done
if test ! -d cortes; then
  mkdir cortes
fi
ffmpeg -ss "$start" -to "$end" -avoid_negative_ts make_zero -i "$video" -i "$image" \
-filter_complex "[0]scale=-1:540.5[vid]; [1]scale=-1:-1[img]; [img][vid] overlay=(W-w)/2:(H-h)/2, \
drawtext=text='$line1': fontfile='SourceSansPro-Black.otf': fontsize=60: fontcolor=white: x=(w-text_w)/2: y=185, \
drawtext=text='$line2': fontfile='SourceSansPro-Black.otf': fontsize=60: fontcolor=white: x=(w-text_w)/2: y=255, \
drawtext=text='$line3': fontfile='SourceSansPro-Black.otf': fontsize=60: fontcolor=white: x=(w-text_w)/2: y=965, \
drawtext=text='$line4': fontfile='SourceSansPro-Black.otf': fontsize=60: fontcolor=white: x=(w-text_w)/2: y=1035" \
-preset ultrafast -c:a aac -v quiet -stats "$folder/cortes/$outputfile" -y
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