When you need to normalize the audio of a video file

normalize.sh

#!/bin/bash
#
# Normalizes the audio in the supplied video file. Will cause some audio
# degradation since there is a recompression step going on here.
#
# You must have a done folder and processed folder in the same path as
# this script.
#
# Script depends on avconv (ffmpeg on ubuntu 14.x) and sox
#
FILE="$1"
OUT="done/$(basename "${FILE}")"

if [ ! -f "${FILE}" ]; then
  echo "No such file: " ${FILE}
  exit 1
fi

echo "Processing \"$(basename "${FILE}")\"..."

if [ -f "${OUT}" ]; then
  echo "Already processed, skipping ${OUT}"
  exit 0
fi

rm processed/*

echo Extracting video...
avconv -v error -i "${FILE}" -vcodec copy -an processed/video.mp4
echo Extracting audio...
avconv -v error -i "${FILE}" -vn processed/audio.wav

echo Normalizing audio...
sox --norm processed/audio.wav processed/audio_norm.wav >/dev/null

echo "Muxing..."
avconv -v error -i processed/video.mp4 -i processed/audio_norm.wav -vcodec copy processed/processed.mp4

echo "Moving result into done"
mv processed/processed.mp4 "${OUT}"

echo "Done"
exit 0