Normalize the audio for a video file and combine it back

normalize.sh

#!/bin/bash
 
fullname=$1
 
filename=$(basename "$fullname")
extension="${filename##*.}"
filename="${filename%.*}"
 
if [ -f "audio.wav" ]
then
  rm audio.wav
fi
 
ffmpeg -i "$fullname" -c:a pcm_s16le audio.wav
 
normalize audio.wav
 
ffmpeg -i "$fullname" -i audio.wav \
       -map 0:0 -map 1:0 -c:v copy \
       -c:a libmp3lame -b:a 192k \
       "${filename}_normalized.${extension}"