Reencode music files from alac to aac

reencode.sh

#!/bin/bash

folder=$1; shift

if test "$folder" == "" ; then
    echo "Please provide a folder containing music to re-encode."
    exit 1
fi

old_codec=${1:-alac}
new_codec=${2:-aac}

destdir=$(dirname "$folder")/Encoded

echo "Writing re-encoded files to $destdir"
echo

find "$folder" -type f -not -name .\* | while read file; do
    #echo "$file"
    outfile=${file/#$folder/$destdir}

    if [ ! -f "$outfile" ]; then
        streams=$(ffprobe -loglevel quiet -show_streams "$file")
        if test "$?" == "1"; then
            echo "ffprobe error $file: $streams"
        else
            echo "$streams" | grep -q -e "codec_name=$old_codec";
            if test "$?" == "0"; then
                dir=$(dirname "$outfile")
                [[ -d "$dir" ]] || mkdir -p "$dir";
                echo "encoding $file"
                ffmpeg -nostdin -loglevel error -y -i "$file" -strict experimental -vn -sn -c:a "$new_codec" "$outfile";
            fi
        fi
    fi
done

./reencode.sh ~/Music/iTunes/iTunes\ Media/Music

Will create files in ~/Music/iTunes/iTunes\ Media/Encoded/.. folder based on files in~/Music/iTunes/iTunes\ Media/Music/....

Copy other files with

rsync -auv --exclude='.*' M/Music/ M/Encoded/