ffmpeg batch script for video resizing - improved

Question

I posted a question here ffmpeg batch script for video resizing but I forgot the issue of the rotation and the video files were scaled with wrong dimensions.

Below is the improved version of the script

#!/bin/bash
set -eu
status=true
fail() {
 echo "$@" >&2
 status=false
}
# Resize a single file
resize() {
 exiftool -p 'Filename:$filename Megapixel:$megapixels Dimension:$imagesize Rotation:$rotation' 1ドル
 if exiftool -if '$imageheight == 1920 && $imageheight == 1080' 1ドル > /dev/null
 then
 fail "-> No need to convert"
 return
 fi
 filename="$(date +%s)".mp4
 rotation=$(exiftool -p '$rotation' 1ドル) 
 if [ "${rotation}" -eq 0 ] || [ "${rotation}" -eq 180 ]
 then
 scaling="-1:720"
 elif [ "${rotation}" -eq 90 ] || [ "${rotation}" -eq 270 ]
 then
 scaling="720:-1"
 else
 fail "-> Unhandled rotation"
 return
 fi
 if 
 ffmpeg -v error -stats -i "1ドル" -map_metadata 0 \
 -vf scale="$scaling" -c:v libx264 -crf 23 \
 -c:a copy "$filename" < /dev/null &&
 exiftool -TagsFromFile "1ドル" '-all:all>all:all' \
 -overwrite_original "$filename"
 then
 # success
 rename 's/.mp4/.success.mp4/' 1ドル 
 mv "$filename" 1ドル
 true
 else
 rename 's/.mp4/.error.mp4/' 1ドル 
 # failed; destroy the evidence
 rm -f "$filename" 2>/dev/null
 fail "-> Failed to convert"
 fi
}
[ $# -gt 0 ] || fail "Usage: 0ドル FILE FILE..."
for arg
do
 if [ -f "$arg" ]
 then
 resize "$arg"
 echo
 elif [ -e "$arg" ]
 then
 fail "$arg: not a plain file or directory"
 else
 fail "$arg: file not found"
 fi
done
exec $status # true or false

Answer 1

Is it intended that date is executed separately for each input, or should all converted files have consistent names (for that use of the script)? It's certainly worth a comment explaining your choice.

I'm not a fan of the big space in the redirection > /dev/null - that makes it harder to parse.

This if/else chain looks a little clumsy:

if [ "${rotation}" -eq 0 ] || [ "${rotation}" -eq 180 ]
then
 scaling="-1:720"
elif [ "${rotation}" -eq 90 ] || [ "${rotation}" -eq 270 ]
then
 scaling="720:-1"
else
 fail "-> Unhandled rotation"
 return
fi

When testing a single value against various possibilities, it tends to be neater using case:

case "$rotation" in
 0|180) scaling="-1:720" ;;
 90|270) scaling="720:-1" ;;
 *) fail "-> Unhandled rotation '$rotation'"; return ;;
esac

(I also added extra information in the failure case, that may help diagnose problem input files).