convert ffmpeg video to vertical with overlay

gistfile1.txt

#!/bin/bash
set -euo pipefail
IFS=$'\n\t'
set -x

FILTERGRAPH="[0:v]pad=iw:2*trunc(iw*16/18):(ow-iw)/2:(oh-ih)/2[padded];[padded]scale=1080:1920[resized];[resized][1:v]overlay"
echo  "nullscr,$FILTERGRAPH,nullsink" | graph2dot
false

for f in $(find input -type f); do
	if [ ! -f "$f" ]; then
		continue
	fi
	converted=output${f#input}.mp4
	if [ -f "$converted" ]; then
		echo "$converted already exist. skipping"
		continue
	fi
	ffmpeg -i "$f" -i Untitled.png -filter_complex "$FILTERGRAPH" -c:v libx264 -crf 18 -map 0:a:0 "$converted"
done