mora file to iOS-compatible m4a converter

mora2ios.sh

#!/usr/bin/env bash

mp4box=/Applications/Osmo4.app/Contents/MacOS/MP4Box
tempname=mora

if [ ! -f "$mp4box" ] || [ ! -x "$mp4box" ]; then
    echo "cannot find mp4box executable" > /dev/stderr
    exit 1
fi

for FILE in "$@"; do
    if [ "${FILE:0-4}" = .mp4 ]; then
        mv -- "$FILE" "${FILE::-4}.m4a"
        FILE="${FILE::-4}.m4a"
    fi

    # get info
    INFO=$("$mp4box" -noprog -quiet -info "$FILE")
    if echo "$INFO" | grep -si error; then
        echo invalid input file: "$FILE" > /dev/stderr
        continue
    fi

    # extract audio
    TEMPDIR=$(mktemp -d -t "$tempname")
    "$mp4box" -noprog -quiet -single 1 -out "$TEMPDIR/output" "$FILE" > /dev/null
    TEMPFILE="$TEMPDIR/output.m4a"

    # extract cover
    "$mp4box" -noprog -quiet -out "$TEMPDIR/cover.jpg" -dump-cover "$FILE" > /dev/null
    if [ -f "$TEMPDIR/cover.jpg" ]; then
        "$mp4box" -noprog -quiet -itags cover="$TEMPDIR/cover.jpg" "$TEMPFILE" > /dev/null
    elif [ -f "$TEMPDIR/cover.png" ]; then
        "$mp4box" -noprog -quiet -itags cover="$TEMPDIR/cover.png" "$TEMPFILE" > /dev/null
    fi

    # write copyright
    COPYRIGHT=$(echo "$INFO" | sed -n '/^Copyrights:$/{n;p;q;}')
    COPYRIGHT=${COPYRIGHT:7} # first character is tab, then 6 characters for region
    if [ -n "$COPYRIGHT" ]; then
        "$mp4box" -noprog -quiet -cprt "$COPYRIGHT" "$TEMPFILE" > /dev/null
    fi

    # write itunes tags
    echo "$INFO" | sed -n '/^iTunes Info:$/,/^$/p' | while IFS= read -r LINE; do
        KEY=$(echo "${LINE:1}" | grep -oE '^[^:]+')
        VALUE=$(echo "${LINE}" | grep -oE '[^:]+$')
        VALUE="${VALUE:1}" # first character is space
        if [[ ! $KEY =~ ^\ *$ ]] && [[ ! $VALUE =~ ^\ *$ ]]; then
            if [ "$KEY" = "Cover Art" ]; then
                continue
            fi
            "$mp4box" -noprog -quiet -itags "$(echo "$KEY" | tr '[A-Z ]' '[a-z_]')"="$VALUE" "$TEMPFILE" > /dev/null
        fi
    done

    mv "$FILE" "$FILE".orig
    cp "$TEMPFILE" "$FILE"

    rm -r "$TEMPDIR"
done