Merge videos with different resolutions using FFMPEG

merge.sh

W=1920
H=1080
fps=fps=24000/1001
out='../out.mp4'
vids=$(ls *.mp4)
n=$(echo "$vids" | wc -l)
inputs=$( for v in $vids; do echo -i; echo $v; done )
filters0=$( for i in $(seq 0 $(($n-1))); do printf "[$i:v]scale=$W:$H:force_original_aspect_ratio=decrease,pad=$W:$H:(ow-iw)/2:(oh-ih)/2,setsar=1/1,setpts=PTS-STARTPTS,fps=$fps[v$i]; "; done )
filters1=$( for i in $(seq 0 $(($n-1))); do printf "[v$i][$i:a]"; done )
ffmpeg -y $inputs -filter_complex "$filters0$filters1 concat=n=$n:v=1:a=1[v][a]" -map "[v]" -map "[a]" "$out"