Merge pull request #211 from utf8please/patch-1

Limit result to one line when parsing cover size.

AAXtoMP3

@@ -9,14 +9,14 @@ usage=$'\nUsage: AAXtoMP3 [--flac] [--aac] [--opus ] [--single] [--level <COMPRE
 [--chaptered] [-e:mp3] [-e:m4a] [-e:m4b] [--authcode <AUTHCODE>] [--no-clobber]
 [--target_dir <PATH>] [--complete_dir <PATH>] [--validate] [--loglevel <LOGLEVEL>]
 [--keep-author <N>] [--author <AUTHOR>] [--{dir,file,chapter}-naming-scheme <STRING>]  
-[--use-audible-cli-data] [--continue <CHAPTERNUMBER>] {FILES}\n'
+[--use-audible-cli-data] [--audible-cli-library-file <LIBRARY_PATH>] [--continue <CHAPTERNUMBER>] {FILES}\n'
 codec=libmp3lame            # Default encoder.
 extension=mp3               # Default encoder extension.
 level=-1                    # Compression level. Can be given for mp3, flac and opus. -1 = default/not specified.
 mode=chaptered              # Multi file output
 auth_code=                  # Required to be set via file or option.
 targetdir=                  # Optional output location.  Note default is basedir of AAX file.
-dirNameScheme=              # Custom directory naming scheme, default is $genre/$author/$title
+dirNameScheme=              # Custom directory naming scheme, default is $genre/$artist/$title
 customDNS=0
 fileNameScheme=             # Custom file naming scheme, default is $title
 customFNS=0
@@ -34,6 +34,10 @@ authorOverride=             # Override the author, ignoring the metadata
 audibleCli=0                # Default off, Use additional data gathered from mkb79/audible-cli
 aaxc_key=                   # Initialize variables, in case we need them in debug_vars
 aaxc_iv=                    # Initialize variables, in case we need them in debug_vars
+ffmpegPath=                 # Set a custom path, useful for using the updated version that supports aaxc
+ffmpegName=ffmpeg           # Set a custom ffmpeg binary name, useful tailoring to local setup
+ffprobeName=ffprobe         # Set a custom ffprobe binary name, useful tailoring to local setup
+library_file=               # Libraryfile generated by mkb79/audible-cli
 
 # -----
 # Code tip Do not have any script above this point that calls a function or a binary.  If you do
@@ -44,8 +48,6 @@ while true; do
   case "$1" in
                       # Flac encoding
     -f | --flac       ) codec=flac; extension=flac; mode=single; container=flac;        shift ;;
-                      # Apple m4a music format.
-    -a | --aac        ) codec=copy; extension=m4a; mode=single; container=m4a;          shift ;;
                       # Ogg Format
     -o | --opus       ) codec=libopus; extension=opus; container=ogg;                   shift ;;
                       # If appropriate use only a single file output.
@@ -55,7 +57,7 @@ while true; do
                       # This is the same as --single option.
     -e:mp3            ) codec=libmp3lame; extension=mp3; mode=single; container=mp3;    shift ;;
                       # Identical to --acc option.
-    -e:m4a            ) codec=copy; extension=m4a; mode=single; container=mp4;          shift ;;
+    -e:m4a | -a | --aac ) codec=copy; extension=m4a; mode=single; container=mp4;          shift ;;
                       # Similar to --aac but specific to audio books
     -e:m4b            ) codec=copy; extension=m4b; mode=single; container=mp4;          shift ;;
                       # Change the working dir from AAX directory to what you choose.
@@ -82,12 +84,20 @@ while true; do
     --continue        ) continueAt="$2"; continue=1;                                    shift 2 ;;
                       # Use additional data got with mkb79/audible-cli
     --use-audible-cli-data ) audibleCli=1;                                              shift ;;
+                      # Path of the library-file, generated by mkb79/audible-cli (audible library export -o ./library.tsv)
+    -L | --audible-cli-library-file ) library_file="$2";                                shift 2 ;;
                       # Compression level
     --level           ) level="$2";                                                     shift 2 ;;
                       # Keep author number n
     --keep-author     ) keepArtist="$2";                                                shift 2 ;;
                       # Author override
     --author          ) authorOverride="$2";                                            shift 2 ;;
+                      # Ffmpeg path override
+    --ffmpeg-path     ) ffmpegPath="$2";                                                shift 2 ;;
+                      # Ffmpeg name override
+    --ffmpeg-name     ) ffmpegName="$2";                                                shift 2 ;;
+                      # Ffprobe name override
+    --ffprobe-name    ) ffprobeName="$2";                                                shift 2 ;;
                       # Command synopsis.
     -h | --help       ) printf "$usage" $0 ;                                            exit ;;
                       # Standard flag signifying the end of command line processing.
@@ -212,6 +222,16 @@ else
     SED="gsed"
 fi
 
+# Use custom ffmpeg (and ffprobe) binary ( --ffmpeg-path flag)
+if [ -n "$ffmpegPath" ]; then
+  FFMPEG="$ffmpegPath/${ffmpegName}"
+  FFPROBE="$ffmpegPath/${ffprobeName}"
+else
+  FFMPEG="${ffmpegName}"
+  FFPROBE="${ffprobeName}"
+fi
+
+debug_vars "ffmpeg/ffprobe paths" FFMPEG FFPROBE
 
 # -----
 # Detect which annoying version of grep we have
@@ -242,7 +262,7 @@ fi
 
 # -----
 # Detect ffmpeg and ffprobe
-if [[ "x$(type -P ffmpeg)" == "x" ]]; then
+if [[ "x$(type -P "$FFMPEG")" == "x" ]]; then
   echo "ERROR ffmpeg was not found on your env PATH variable"
   echo "Without it, this script will break."
   echo "INSTALL:"
@@ -255,7 +275,7 @@ fi
 
 # -----
 # Detect ffmpeg and ffprobe
-if [[ "x$(type -P ffprobe)" == "x" ]]; then
+if [[ "x$(type -P "$FFPROBE")" == "x" ]]; then
   echo "ERROR ffprobe was not found on your env PATH variable"
   echo "Without it, this script will break."
   echo "INSTALL:"
@@ -402,7 +422,7 @@ validate_aax() {
   set +e errexit
 
   # Take a look at the aax file and see if it is valid. If the source file is aaxc, we give ffprobe additional flags
-  output="$(ffprobe -loglevel warning ${decrypt_param} -i "${media_file}" 2>&1)"
+  output="$("$FFPROBE" -loglevel warning ${decrypt_param} -i "${media_file}" 2>&1)"
 
   # If invalid then say something.
   if [[ $? != "0" ]] ; then
@@ -415,7 +435,7 @@ validate_aax() {
 
   # This is a big test only performed when the --validate switch is passed.
   if [[ "${VALIDATE}" == "1" ]]; then
-    output="$(ffmpeg -hide_banner ${decrypt_param} -i "${media_file}" -vn -f null - 2>&1)"
+    output="$("$FFMPEG" -hide_banner ${decrypt_param} -i "${media_file}" -vn -f null - 2>&1)"
     if [[ $? != "0" ]] ; then
       log "ERROR: Invalid File: ${media_file}"
     else
@@ -477,6 +497,15 @@ validate_extra_files() {
     return 1
   fi
 
+  # Test for library file
+  if [[ ! -r "${library_file}" ]] ; then
+    library_file_exists=0
+    debug "library file not found"
+  else
+    library_file_exists=1
+    debug "library file found"
+  fi
+
   debug "All expected audible-cli related file are here"
 }
 
@@ -485,7 +514,7 @@ validate_extra_files() {
 save_metadata() {
   local media_file
   media_file="$1"
-  ffprobe -i "$media_file" 2> "$metadata_file"
+  "$FFPROBE" -i "$media_file" 2> "$metadata_file"
   if [[ $(type -P mediainfo) ]]; then
     echo "Mediainfo data START" >> "$metadata_file"
     # Mediainfo output is structured like ffprobe, so we append it to the metadata file and then parse it with get_metadata_value()
@@ -507,9 +536,42 @@ save_metadata() {
     # we use some characters (#) as placeholder, add some new lines,
     # put a ',' after the start value, we calculate the end of each chapter
     # as start+length, and we convert (divide) the time stamps from ms to s.
-    # Then we delete all ':' since they make a filename invalid.
+    # Then we delete all ':' and '/' since they make a filename invalid.
     jq -r '.content_metadata.chapter_info.chapters[] | "Chapter # start: \(.start_offset_ms/1000), end: \((.start_offset_ms+.length_ms)/1000) \n#\n# Title: \(.title)"' "${extra_chapter_file}" \
-      | tr -d ':' >> "$metadata_file"
+      | $SED 's@[:/]@@g' >> "$metadata_file"
+    # In case we want to use a single file m4b we need to extract the
+    # chapter titles from the .json generated by audible–cli and store
+    # them correctly formatted for mp4chaps in a chapter.txt
+    if [ "${mode}" == "single" ]; then
+      # Creating a temp file to store the chapter data collected in save_metadata, as the output
+      # folder will only be defined after save_metadata has been executed.
+      # This file is only required when using audible-cli data and executing in single mode to
+      # get proper chapter titles in single file m4b output.
+      tmp_chapter_file="${working_directory}/chapter.txt"
+      jq -r \
+        'def pad(n): tostring | if (n > length) then ((n - length) * "0") + . else . end;
+        .content_metadata.chapter_info.chapters |
+        reduce .[] as $c ([]; if $c.chapters? then .+[$c | del(.chapters)]+[$c.chapters] else .+[$c] end) | flatten |
+        to_entries |
+        .[] |
+        "CHAPTER\((.key))=\((((((.value.start_offset_ms / (1000*60*60)) /24 | floor)  *24 ) + ((.value.start_offset_ms / (1000*60*60)) %24 | floor)) | pad(2))):\(((.value.start_offset_ms / (1000*60)) %60 | floor | pad(2))):\(((.value.start_offset_ms / 1000) %60 | floor | pad(2))).\((.value.start_offset_ms % 1000 | pad(3)))
+CHAPTER\((.key))NAME=\(.value.title)"' "${extra_chapter_file}" > "${tmp_chapter_file}"
+    fi
+
+    # get extra meta data from library.tsv
+    if [[ "${library_file_exists}" == 1 ]]; then
+      asin=$(jq -r '.content_metadata.content_reference.asin' "${extra_chapter_file}")
+      if [[ ! -z "${asin}" ]]; then
+        lib_entry=$($GREP "^${asin}" "${library_file}")
+        if [[ ! -z "${lib_entry}" ]]; then
+          series_title=$(echo "${lib_entry}" | awk -F '\t' '{print $6}')
+          series_sequence=$(echo "${lib_entry}" | awk -F '\t' '{print $7}')
+          $SED -i "/^  Metadata:/a\\
+    series          : ${series_title}\\
+    series_sequence : ${series_sequence}" "${metadata_file}"
+        fi
+      fi
+    fi
   fi
   debug "Metadata file $metadata_file"
   debug_file "$metadata_file"
@@ -617,6 +679,8 @@ do
   album="$(get_metadata_value album)"
   album_date="$(get_metadata_value date)"
   copyright="$(get_metadata_value copyright)"
+  series="$(get_metadata_value series)"
+  series_sequence="$(get_metadata_value series_sequence)"
 
   # Get more tags with mediainfo
   if [[ $(type -P mediainfo) ]]; then
@@ -639,9 +703,9 @@ do
 
   # If we defined a target directory, use it. Otherwise use the location of the AAX file
   if [ "x${targetdir}" != "x" ] ; then
-    output_directory="${targetdir}/${currentDirNameScheme}/"
+    output_directory="${targetdir}/${currentDirNameScheme}"
   else
-    output_directory="$(dirname "${aax_file}")/${currentDirNameScheme}/"
+    output_directory="$(dirname "${aax_file}")/${currentDirNameScheme}"
   fi
 
   # Define the output_file
@@ -654,8 +718,9 @@ do
   output_file="${output_directory}/${currentFileNameScheme}.${extension}"
 
   if [[ "${noclobber}" = "1" ]] && [[ -d "${output_directory}" ]]; then
-    log "Noclobber enabled but directory '${output_directory}' exists. Exiting to avoid overwriting"
-    exit 0
+    log "Noclobber enabled but directory '${output_directory}' exists. Skipping to avoid overwriting"
+    rm -f "${metadata_file}" "${tmp_chapter_file}"
+    continue
   fi
   mkdir -p "${output_directory}"
 
@@ -674,7 +739,7 @@ do
 
   # Display the total length of the audiobook in format hh:mm:ss
   # 10#$var force base-10 interpretation. By default it's base-8, so values like 08 or 09 are not octal numbers
-  total_length="$(ffprobe -v error ${decrypt_param} -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "${aax_file}" | cut -d . -f 1)"
+  total_length="$("$FFPROBE" -v error ${decrypt_param} -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "${aax_file}" | cut -d . -f 1)"
   hours="$((total_length/3600))"
   if [ "$((hours<10))" = "1" ]; then hours="0$hours"; fi
   minutes="$((total_length/60-60*10#$hours))"
@@ -693,8 +758,8 @@ do
   if [ "${continue}" == "0" ]; then
     # This is the main work horse command.  This is the primary transcoder.
     # This is the primary transcode. All the heavy lifting is here.
-    debug 'ffmpeg -loglevel error -stats ${decrypt_param} -i "${aax_file}" -vn -codec:a "${codec}" -ab ${bitrate} -map_metadata -1 -metadata title="${title}" -metadata artist="${artist}" -metadata album_artist="${album_artist}" -metadata album="${album}" -metadata date="${album_date}" -metadata track="1/1" -metadata genre="${genre}" -metadata copyright="${copyright}" "${output_file}"'
-    </dev/null ffmpeg -loglevel error \
+    debug '"$FFMPEG" -loglevel error -stats ${decrypt_param} -i "${aax_file}" -vn -codec:a "${codec}" -ab ${bitrate} -map_metadata -1 -metadata title="${title}" -metadata artist="${artist}" -metadata album_artist="${album_artist}" -metadata album="${album}" -metadata date="${album_date}" -metadata track="1/1" -metadata genre="${genre}" -metadata copyright="${copyright}" "${output_file}"'
+    </dev/null "$FFMPEG" -loglevel error \
       -stats \
       ${decrypt_param} \
       -i "${aax_file}" \
@@ -714,6 +779,8 @@ do
       -metadata description="${description}" \
       -metadata composer="${narrator}" \
       -metadata publisher="${publisher}" \
+      -metadata series="${series}" \
+      -metadata series_sequence="${series_sequence}" \
       -f ${container} \
       "${output_file}"
     if [ "$((${loglevel} > 0))" == "1" ]; then
@@ -722,8 +789,7 @@ do
     # -----
   fi
   # Grab the cover art if available.
-  cover_file="${output_directory}/cover.jpg"
-  extra_crop_cover=''
+  cover_file="${output_directory}/${currentFileNameScheme}.jpg"
   if [ "${continue}" == "0" ]; then
     if [ "${audibleCli}" == "1" ]; then
       # We have a better quality cover file, copy it.
@@ -731,21 +797,27 @@ do
         log "Copy cover file to ${cover_file}..."
       fi
       cp "${extra_cover_file}" "${cover_file}"
-
-      # We now set a variable, ${extra_crop_cover}, which contains an additional
-      # ffmpeg flag. It crops the cover so the width and the height is divisible by two.
-      # Since the standard (in the aax file) image resolution is 512, we set the flag
-      # only if we use a custom cover art.
-      extra_crop_cover='-vf crop=trunc(iw/2)*2:trunc(ih/2)*2'
     else
       # Audible-cli not used, extract the cover from the aax file
       if [ "$((${loglevel} > 1))" == "1" ]; then
         log "Extracting cover into ${cover_file}..."
       fi
-      </dev/null ffmpeg -loglevel error -activation_bytes "${auth_code}" -i "${aax_file}" -an -codec:v copy "${cover_file}"
+      </dev/null "$FFMPEG" -loglevel error -activation_bytes "${auth_code}" -i "${aax_file}" -an -codec:v copy "${cover_file}"
     fi
   fi
 
+  extra_crop_cover=''
+  cover_width=$(ffprobe -i "${cover_file}" 2>&1 | $GREP -Po "[0-9]+(?=x[0-9]+)" | tail -n 1)
+  if (( ${cover_width} % 2 == 1 )); then
+    if [ "$((${loglevel} > 1))" == "1" ]; then
+      log "Cover ${cover_file} has odd width ${cover_width}, setting extra_crop_cover to make even."
+    fi
+    # We now set a variable, ${extra_crop_cover}, which contains an additional
+    # ffmpeg flag. It crops the cover so the width and the height is divisible by two.
+    # Set the flag only if we use a cover art with an odd width.
+    extra_crop_cover='-vf crop=trunc(iw/2)*2:trunc(ih/2)*2'
+  fi
+
   # -----
   # If mode=chaptered, split the big converted file by chapter and remove it afterwards.
   # Not all audio encodings make sense with multiple chapter outputs (see options section)
@@ -823,7 +895,7 @@ do
         #ffmpeg version 4+ and on the output for all older versions.
         split_input=""
         split_output=""
-        if [ "$(($(ffmpeg -version | $SED -E 's/[^0-9]*([0-9]).*/\1/g;1q') > 3))" = "1" ]; then
+        if [ "$(($("$FFMPEG" -version | $SED -E 's/[^0-9]*([0-9]).*/\1/g;1q') > 3))" = "1" ]; then
           split_input="-ss ${chapter_start%?} -to ${chapter_end}"
         else
           split_output="-ss ${chapter_start%?} -to ${chapter_end}"
@@ -837,7 +909,7 @@ do
           if [ "$((${loglevel} > 1))" == "1" ]; then
             log "Splitting chapter ${chapternum}/${chaptercount} start:${chapter_start%?}(s) end:${chapter_end}(s)"
           fi
-          </dev/null ffmpeg -loglevel quiet \
+          </dev/null "$FFMPEG" -loglevel quiet \
             -nostats \
             ${split_input} \
             -i "${output_file}" \
@@ -848,7 +920,7 @@ do
             -map 1:0 \
             -acodec ${chapter_codec} \
             -metadata:s:v title="Album cover" \
-            -metadata:s:v comment="Cover (Front)" \
+            -metadata:s:v comment="Cover (front)" \
             -metadata track="${chapternum}" \
             -metadata title="${chapter}" \
             -metadata:s:a title="${chapter}" \
@@ -882,12 +954,46 @@ do
     # Perform file tasks on output file.
     # ----
     # ffmpeg seems to copy only chapter position, not chapter names.
+    # use already created chapter.txt from save_metadata() in case
+    # audible-cli data is used else use ffprobe to extract from m4b
     if [[ ${container} == "mp4" && $(type -P mp4chaps) ]]; then
-      ffprobe -i "${aax_file}" -print_format csv -show_chapters 2>/dev/null | awk -F "," '{printf "CHAPTER%02d=%02d:%02d:%02.3f\nCHAPTER%02dNAME=%s\n", NR, $5/60/60, $5/60%60, $5%60, NR, $8}' > "${output_directory}/${currentFileNameScheme}.chapters.txt"
+      if [ "${audibleCli}" == "1" ]; then
+        mv "${tmp_chapter_file}" "${output_directory}/${currentFileNameScheme}.chapters.txt"
+      else
+        "$FFPROBE" -i "${aax_file}" -print_format csv -show_chapters 2>/dev/null | awk -F "," '{printf "CHAPTER%d=%02d:%02d:%02.3f\nCHAPTER%dNAME=%s\n", NR, $5/60/60, $5/60%60, $5%60, NR, $8}' > "${output_directory}/${currentFileNameScheme}.chapters.txt"
+      fi
+      $SED -i 's/\,000/\.000/' "${output_directory}/${currentFileNameScheme}.chapters.txt"
       mp4chaps -i "${output_file}"
     fi
   fi
 
+  if [ -f "${cover_file}" ]; then
+    log "Adding cover art"
+    # FFMPEG does not support MPEG-4 containers fully #
+    if [ "${container}" == "mp4" ] ; then
+      mp4art --add "${cover_file}" "${output_file}"
+    # FFMPEG for everything else #
+    else
+      # Create temporary output file name - ensure extention matches previous appropriate output file to keep ffmpeg happy
+      cover_output_file="${output_file%.*}.cover.${output_file##*.}"
+      # Copy audio stream from current output, and video stream from cover file, setting appropriate metadata
+      </dev/null "$FFMPEG" -loglevel quiet \
+        -nostats \
+        -i "${output_file}" \
+        -i "${cover_file}" \
+        -map 0:a:0 \
+        -map 1:v:0 \
+        -acodec copy \
+        -vcodec copy \
+        -id3v2_version 3 \
+        -metadata:s:v title="Album cover" \
+        -metadata:s:v comment="Cover (front)" \
+        "${cover_output_file}"
+        # Replace original output file with version including cover
+        mv "${cover_output_file}" "${output_file}"
+    fi
+  fi
+
   # -----
   # Announce that we have completed the transcode
   if [ "$((${loglevel} > 0))" == "1" ]; then

README.md

@@ -25,7 +25,7 @@ Audible fails for some reason.
 
 ## Usage(s)
 ```
-bash AAXtoMP3 [-f|--flac] [-o|--opus] [-a|-aac] [-s|--single] [--level <COMPRESSIONLEVEL>] [-c|--chaptered] [-e:mp3] [-e:m4a] [-e:m4b] [-A|--authcode <AUTHCODE>] [-n|--no-clobber] [-t|--target_dir <PATH>] [-C|--complete_dir <PATH>] [-V|--validate] [--use-audible-cli-data]] [-d|--debug] [-h|--help] [--continue <CHAPTERNUMBER>] <AAX/AAXC INPUT_FILES>...
+bash AAXtoMP3 [-f|--flac] [-o|--opus] [-a|--aac] [-s|--single] [--level <COMPRESSIONLEVEL>] [-c|--chaptered] [-e:mp3] [-e:m4a] [-e:m4b] [-A|--authcode <AUTHCODE>] [-n|--no-clobber] [-t|--target_dir <PATH>] [-C|--complete_dir <PATH>] [-V|--validate] [--use-audible-cli-data]] [-d|--debug] [-h|--help] [--continue <CHAPTERNUMBER>] <AAX/AAXC INPUT_FILES>...
 ```
 or if you want to get guided through the options
 ```
@@ -57,6 +57,10 @@ bash interactiveAAXtoMP3 [-a|--advanced] [-h|--help]
 * **--file-naming-scheme &lt;STRING&gt;** or **-F**    Use a custom file naming scheme, with variables. See [below](#custom-naming-scheme) for more info.
 * **--chapter-naming-scheme &lt;STRING&gt;**  Use a custom chapter naming scheme, with variables. See [below](#custom-naming-scheme) for more info.
 * **--use-audible-cli-data** Use additional data got with mkb79/audible-cli. See [below](#audible-cli-integration) for more info. Needed for the files in the `aaxc` format.
+* **--audible-cli-library-file** or **-L** Path of the library-file, generated by mkb79/audible-cli (`audible library export -o ./library.tsv`). Only available if `--use-audible-cli-data` is set. This file is required to parse additional metadata such as `$series` or `$series_sequence`.
+* **--ffmpeg-path**  Set the ffmpeg/ffprobe binaries folder. Both of them must be executable and in the same folder.
+* **--ffmpeg-name**  Set a custom name for the ffmpeg binary. Must be executable and in path, or in custom path specified by --ffmpeg-path.
+* **--ffprobe-name**  Set a custom name for the ffprobe binary. Must be executable and in path, or in custom path specified by --ffmpeg-path.
 
 ## Options for interactiveAAXtoMP3
 * **-a** or **--advanced** Get more options to choose. Not used right now.
@@ -150,6 +154,10 @@ So you can use `--dir-naming-scheme '$(date +%Y)/$artist'`, but using `--file-na
 * If you want shorter chapter names, use `--chapter-naming-scheme '$(printf %0${#chaptercount}d $chapternum) $chapter'`: only chapter number and chapter name
 * If you want to append the narrator name to the title, use `--dir-naming-scheme '$genre/$artist/$title-$narrator' --file-naming-scheme '$title-$narrator'`
 * If you don't want to have the books separated by author, use `--dir-naming-scheme '$genre/$title'`
+* To be able to use `$series` or `$series_sequence` in the schemes the following is required:
+  * `--use-audible-cli-data` is set
+  * you have pre-generated the library-file via `audible library export -o ./library.tsv`
+  * you have set the path to the generated library-file via `--audible-cli-library-file ./library.tsv`
 
 ### Installing Dependencies.
 In general, take a look at [command-not-found.com](https://command-not-found.com/)
@@ -160,6 +168,20 @@ sudo apt-get update
 sudo apt-get install ffmpeg libav-tools x264 x265 bc
 ```
 
+In Debian-based system's repositories the ffmpeg version is often outdated. If you want
+to convert .aaxc files, you need at least ffmpeg 4.4. So if your installed version
+needs to be updated, you can either install a custom repository that has the newer version,
+compile ffmpeg from source or download pre-compiled binaries.
+You can then tell AAXtoMP3 to use the compiled binaries with the `--ffmpeg-path` flag.
+You need to specify the folder where the ffmpeg and ffprobe binaries are. Make sure
+they are both executable.
+
+If you have snapd installed, you can also install a recent version of 4.4 from the edge channel:
+```
+snap install ffmpeg --edge
+```
+In this case you will need to confiure a custom path _and_ binary name for ffprobe, `--ffmpeg-path /snap/bin/ --ffprobe-name ffmpeg.ffprobe`.
+
 __Fedora__
 
 Fedora users need to enable the rpm fusion repository to install ffmpeg. Version 22 and upwards are currently supported. The following command works independent of your current version:
@@ -198,13 +220,17 @@ brew install findutils
 ```
 
 #### mp4art/mp4chaps
-_Note: This is an optional dependency._
+_Note: This is an optional dependency, required for adding cover art to m4a and b4b files only._
 
 __Ubuntu, Linux Mint, Debian__
 ```
 sudo apt-get update
 sudo apt-get install mp4v2-utils
 ```
+
+On Debian and Ubuntu the mp4v2-utils package has been deprecated and removed, as the upsteam project is no longer maintained.
+The package was removed in Debian Buster, and Ubuntu Focal [ 20.04 ].
+
 __CentOS, RHEL & Fedora__
 ```
 # CentOS/RHEL and Fedora users make sure that you have enabled atrpms repository in system. Let’s begin installing FFmpeg as per your operating system.
@@ -239,6 +265,7 @@ Since getting those keys is not simple, for now the method used to get them
 is handled by the package audible-cli, that stores
 them in a file when downloading the aaxc file. This means that in order to
 decrypt the aaxc files, they must be downloaded with audible-cli.
+Note that you need at least [ffmpeg 4.4](#ffmpegffprobe).
 
 ## Audible-cli integration
 Some information are not present in the AAX file. For example the chapters's