Synology Re-encode AAC script v1.1

#!/bin/sh

# Credits to:
# User jeppo77 + http://blog.mobile-harddisk.nl/tutorials/workaround-voor-dts-video-op-ds214play/
#
# Example Usage: /volume1/scripts/Audioconverter/convert.sh /volume1/video/
#

#Directories must be defined without trailing slash
rootpath="/volume1/scripts/Audioconverter"

#leave as is.
ffprobe="$rootpath/ffprobe"
ffmpeg="$rootpath/ffmpeg"
log="$rootpath/convert.log"

echo "This script will reencode audio from video files in: $1"
echo "Logfile is: $log"

#Check if any arguments were passed
if [ -z "$1" ]
then
        echo
        echo "Usage: convert.sh [DIR]"
        exit 0
else
        # create new/ empty log
        echo "----- START ------" > "$log"
        echo
        find $1 -name "*.mkv" -type f | while read f
        do
                echo "processing $f" >> "$log"
                # get number of audio streams
                #num_streams=$($ffprobe "$f" -show_streams 2>&1 | grep "codec_type=audio" -c)
                #echo "streams = $num_streams" >> "$log"

                # Detect what audio codec is being used:
                audio=$($ffprobe "$f" 2>&1 | grep Audio | sed -n '/Audio:/s/.*: \([a-zA-Z0-9]*\).*/\1/p' | sed 1q)
                echo "audio = $audio" >> "$log"

                ##  Set default mapping settings:
                mopts="-map 0"
                ##  Set default subtitle settings:
                sopts="-c:s copy"
                ##  Set default video settings:
                vopts="-c:v copy"
                ## Set default audio settings:
                aopts="-c:a:1 aac -b:a 640k "
                ##  Set extra settings:
                eopts=" -strict -2"

                case "$audio" in
                   aac|alac|mp3|mp2) echo "-----> no processing needed." >> "$log" ;;
                   "") echo "-----> can't determine audio, skipping" >> "$log" ;;
                   *)

                                mv "$f" "$f"-1
                                #convert to aac surround
                                $ffmpeg -nostdin -y -i "$f"-1 $mopts $sopts $vopts $aopts $eopts "$f"

                                fail=$?
                                case "$fail" in
                                        "0" )
                                                ##  put new file in place
                                                echo "-----> SUCCES" >> "$log"
                                                #remove old file
                                                rm -rf "$f"-1
                                                #set rights
                                                chmod 666 "$f"
                                                #first remove than add to synology index
                                                synoindex -D "$f" >> "$log"
                                                synoindex -A "$f" >> "$log"
                                   ;;
                                   * )
                                                echo "-----> FAIL" >> "$log"
                                                ##  revert back
                                                rm -rf "$f"
                                                mv "$f"-1 "$f"
                                   ;;
                                 esac

                   ;;
                esac

        done
fi

exit 0