!/bin/bash

A simple bash script to convert a mp3 based by-track-splitted audio book into one m4b file

set -o errexit

set -o nounset

if [ -z "$1" ]; then

echo "The first param needs to be to folder to convert..."

exit 1;

elif ! [ -d "$1" ]; then

echo "$1 could not be found or is not a directory."

exit 1;

fi

if ! [ -x "$(command -v ffmpeg)" ] || ! [ -x "$(command -v ffprobe)" ] || ! [ -x "$(command -v mpg123)" ] || ! [ -x "$(command -v faac)" ]; then

echo "Required programms are not installed. You need ffmpeg, ffprobe, mpg123 and faac." >&2

exit 1;

fi

some cleanup if the script has crashed

if [ -f /tmp/audiobookgen_tmp.m4b ]; then

rm /tmp/audiobookgen_tmp.m4b

fi

if [ -f /tmp/audiobookgen_FFMETADATAFILE.txt ]; then

rm /tmp/audiobookgen_FFMETADATAFILE.txt

fi

some initial vars

startts=0

title=

artist=

album=

disc=

date=

chapters=

counttracks=0

183 is a audiobook, but it's not standard id3v2. check "id3v2 -L" for a complete list of supported types

genre=12

let the script know where it is, where the source is and set the name of the m4b.

currentDir=$(pwd -P)

mp3audiobookdir=$(realpath "$1")

m4bfileName=$(basename "$mp3audiobookdir")

echo "checking mp3 files..."

cd "$mp3audiobookdir"

for f in *.mp3; do

#all=$(ffprobe  -loglevel quiet -show_entries format_tags "$f");

title=$(ffprobe -loglevel quiet -show_entries format_tags=title -of default=noprint_wrappers=1:nokey=1 "$f")

track=$(ffprobe  -loglevel quiet -show_entries format_tags=track -of default=noprint_wrappers=1:nokey=1 "$f")

if [ -z "$artist" ]; then	

	artist=$(ffprobe  -loglevel quiet -show_entries format_tags=artist -of default=noprint_wrappers=1:nokey=1 "$f")

fi

if [ -z "$album" ]; then	

	album=$(ffprobe  -loglevel quiet -show_entries format_tags=album -of default=noprint_wrappers=1:nokey=1 "$f")

fi	

if [ -z "$disc" ]; then	

	disc=$(ffprobe  -loglevel quiet -show_entries format_tags=disc -of default=noprint_wrappers=1:nokey=1 "$f")

fi	

if [ -z "$date" ]; then	

	date=$(ffprobe  -loglevel quiet -show_entries format_tags=date -of default=noprint_wrappers=1:nokey=1 "$f")

fi

duration=$(ffprobe -v error -show_entries stream=duration -of default=noprint_wrappers=1:nokey=1 "$f")

duration=$(echo "$duration" | awk -F'.' '{print $1}')

chapterstart=$(echo "$startts * 1000 + 1" | bc)

chapterend=$(echo "($startts + $duration) * 1000" | bc)

startts=$(echo "$startts + $duration" | bc)

counttracks=$(echo "$counttracks + 1" | bc)

chapters="$chapters\n\n[CHAPTER]\nTIMEBASE=1/1000\nSTART=$chapterstart\nEND=$chapterend\ntitle=$title"

done

coverparam=

if [ -f "cover.jpg" ]; then

coverparam="--cover-art cover.jpg"

fi

let's show you what i got...

clear

echo -e "Title: $artist - $album\nTracks: $counttracks";

if [ -z "$date" ]; then

echo "Cover:  not found (place cover.jpg in your mp3 directory...)"

else

echo "Cover:  found"

fi

echo -e "Target: $currentDir/$m4bfileName.m4b\n\nPress return to contiune (c for cancel) "

read -n 1 k <&1

if [[ $k = c ]] ; then

exit 0

fi

clear

i'm not setting a "track title" here. if you want to set it add '--title ="$album"' for example

mpg123 -s *.mp3 | faac -P -X -w -o /tmp/audiobookgen_tmp.m4b --artist "$artist" --album "$album" --genre "$genre" --year "$date" --disc "$disc" $coverparam -

cd "$currentDir"

ffmpeg -i /tmp/audiobookgen_tmp.m4b -f ffmetadata /tmp/audiobook_FFMETADATAFILE.txt

echo -e $chapters >> /tmp/audiobook_FFMETADATAFILE.txt

ffmpeg -i /tmp/audiobookgen_tmp.m4b -i /tmp/audiobook_FFMETADATAFILE.txt -map_metadata 1 -vn -sn -dn -acodec copy "$currentDir/$m4bfileName.m4b"

rm /tmp/audiobookgen_tmp.m4b

rm /tmp/audiobook_FFMETADATAFILE.txt

if you have problems with the m4b ffmpeg creates, try these lines (https://trac.ffmpeg.org/ticket/8375):

if [ -x "$(command -v MP4Box)" ]; then

MP4Box -brand M4A:0 -rb isom -rb iso2 "$currentDir/$m4bfileName.m4b"

MP4Box -brand M4A:0 -ab isom -ab iso2 "$currentDir/$m4bfileName.m4b"

fi

echo -e "\ndone."