truckmusic: Script to sync music truck USB stick

Compares the files in `~/.homeshare/Music` and `~/.homeshare/TRUCKMUSIC`
and creates any that are missing or updates those that are outdated.

Uses `ffmpeg` to convert from FLAC to MP3.  Embeds album art in each
file (since that's the only way to display them in the truck).

truckmusic.sh

@@ -0,0 +1,103 @@
+#!/bin/.sh
+# vim: set sw=4 ts=4 sts=4 et :
+
+clean() {
+    echo "$1" | sed \
+        -e "s/’/'/g" \
+        -e 's/?//g' \
+        -e 's@ / @ _ @g' \
+        -e 's@/@-@g' \
+        -e 's/: / - /g' \
+        -e 's/:/-/g' \
+        -e 's/\.\+$//'
+}
+
+convert() {
+    unset src dst cover
+    src="${1}"
+    dst="${2}"
+
+    cover="${src%/*}/folder.jpg"
+
+    mkdir -p "${dst%/*}"
+    echo "${dst}" >> /tmp/modified.txt
+    printf 'Converting %s to %s ...\n' "${src##*/}" "${dst##*/}"
+    ffmpeg \
+        -loglevel warning \
+        -i "${src}" \
+        -vn \
+        -ar 44100 \
+        -ac 2 \
+        -b:a 256k \
+        "${dst}" \
+        < /dev/null \
+        || return $?
+    if [ -f "${cover}" ]; then
+        printf 'Embedding %s in %s ...\n' "${cover##*/}" "${dst##*/}"
+        ffmpeg \
+            -loglevel warning \
+            -i "${dst}" \
+            -i "${cover}" \
+            -c copy \
+            -map 0:0 \
+            -map 1:0 \
+            -id3v2_version 3 \
+            -metadata:s:v title='Album Cover' \
+            -metadata:s:v comment='Cover (Front)' \
+            "${dst%.mp3}.new.mp3" \
+            < /dev/null \
+            || return $?
+        mv "${dst%.mp3}.new.mp3" "${dst}"
+    fi
+}
+
+rm -f /tmp/modified.txt
+cd ~/.homeshare
+find Music -name '*.flac' -printf '%T@%p\n' \
+    | sed -E 's/^([0-9]+)(\.[0-9]+)(.*)/\1\3/' \
+    | sort -t '' -k2 \
+    > /tmp/music.txt
+while IFS='' read timestamp filename; do
+    album=$(metaflac --show-tag=album "${filename}" | sed 's/^album=//')
+    albumartist=$(metaflac --show-tag=albumartist "${filename}" \
+        | sed 's/^albumartist=//' \
+        | head -n1)
+    artist=$(metaflac --show-tag=artist "${filename}" \
+        | sed 's/^artist=//' \
+        | head -n1)
+    discnumber=$(metaflac --show-tag=discnumber "${filename}" \
+        | sed 's/^discnumber=//')
+    disctotal=$(metaflac --show-tag=disctotal "${filename}" \
+        | sed 's/^disctotal=//')
+    tracknumber=$(metaflac --show-tag=tracknumber "${filename}" \
+        | sed 's/^tracknumber=//')
+    title=$(metaflac --show-tag=title "${filename}" | sed 's/^title=//')
+    if [ -n "${disctotal}" ] || [ "${discnumber:-0}" -gt 0 ]; then
+        newfilename=$(printf \
+            '%s - %s Disc %d/%02d %s - %s.mp3' \
+            "$(clean "${albumartist:-${artist}}")" \
+            "$(clean "${album}")" \
+            "${discnumber:-1}" \
+            "${tracknumber:-0}" \
+            "$(clean "${artist}")" \
+            "$(clean "${title}")"
+        )
+    else
+        newfilename=$(printf \
+            '%s - %s/%02d %s - %s.mp3' \
+            "$(clean "${albumartist:-${artist}}")" \
+            "$(clean "${album}")" \
+            "${tracknumber:-0}" \
+            "$(clean "${artist}")" \
+            "$(clean "${title}")"
+        )
+    fi
+    if [ ! -f "TRUCKMUSIC/${newfilename}" ]; then
+        convert "${filename}" "TRUCKMUSIC/${newfilename}"
+    else
+        newtimestamp=$(stat -c %Y "TRUCKMUSIC/${newfilename}")
+        if [ "${timestamp}" -gt "${newtimestamp}" ]; then
+            convert "${filename}" "TRUCKMUSIC/${newfilename}"
+        fi
+    fi
+done < /tmp/music.txt