for ((i=0; i<${#IN_FILES[@]}; i++)); do
    if ((CHAPTERS > 0)); then
        if [[ ${GROUP[i]} ]]; then
            while read line; do
                group_chapt_array[i]="$(for p in $line; do echo -n $(format_seconds $p),; done)"
            done <<< "$( make_group_chapters "${GROUP_CHAPTERS[i]}")"
        fi
    fi
done