loudnorm

#!/bin/sh

#===============================================================================
# loudnorm
# ffmpeg loudnorm
#===============================================================================

# dependencies:
# ffmpeg

#===============================================================================
# script usage
#===============================================================================

usage()
{
# if argument passed to function echo it
[ -z "${1}" ] || echo "! ${1}"
# display help
echo "\
# ffmpeg loudnorm

$(basename "$0") -i input.(mp4|mkv|mov|m4v|aac|m4a|wav|mp3)"
exit 2
}


#===============================================================================
# error messages
#===============================================================================

INVALID_OPT_ERR='Invalid option:'
REQ_ARG_ERR='requires an argument'
WRONG_ARGS_ERR='wrong number of arguments passed to script'


#===============================================================================
# check the number of arguments passed to the script
#===============================================================================

[ $# -gt 0 ] || usage "${WRONG_ARGS_ERR}"


#===============================================================================
# getopts check the options passed to the script
#===============================================================================

while getopts ':i:h' opt
do
  case ${opt} in
     i) infile="${OPTARG}";;
     h) usage;;
     \?) usage "${INVALID_OPT_ERR} ${OPTARG}" 1>&2;;
     :) usage "${INVALID_OPT_ERR} ${OPTARG} ${REQ_ARG_ERR}" 1>&2;;
  esac
done
shift $((OPTIND-1))


#===============================================================================
# functions
#===============================================================================

# ffmpeg loudnorm get stats from file
normalize () {
    ffmpeg \
    -hide_banner \
    -i "${infile}" \
    -af "loudnorm=I=-16:dual_mono=true:TP=-1.5:LRA=11:print_format=summary" \
    -f null -
}

# run the normalize function
normalize "${infile}"