Remove background audio noise from a video clip via the command line (using ffmpeg and sox)

denoise.sh

#!/bin/bash

if [ -z "$2" ];then
  echo 'USAGE:

    denoise input.mov output.mov

OR 

    denoise input.mov output.mov [ambient-noise-start-time] [ambient-noise-duration] [sox-noisered-amount] [sox-norm-param]

E.G, EXPLICIT DEFAULTS

    denoise input.mov output.mov 00:00:00  00:00:00.3 0.2 -1

PROCESS ALL VIDEOS IN DIRECTORY:

    for f in `find . -type f | grep -iE "\.mov$|\.mp4$"`;do denoise "${f%.*}"{,-rn}."${f##*.}";done
'
  exit 0
fi

INPUT="$1"
OUTPUT="$2"

if [ $# -ge 3 ]
then
  SS="$3"
else
  SS="00:00:00"
fi

if [ $# -ge 4 ]
then
  T="$4"
else
  T="00:00:00.3"
fi

if [ $# -ge 5 ]
then
  NR="$5"
else
  NR="0.2"
fi

if [ $# -ge 6 ]
then
  N="$6"
else
  N="-1"
fi

# auxiliary files
TMP_NOISE_WAV="noise.wav"
TMP_NOISE_PRO="noise_profile_file"
TMP_INPUT="input_audio.wav"
TMP_OUTPUT="output_audio.wav"

# https://unix.stackexchange.com/a/427343/238156

# assume first 0.3 secs are noise
ffmpeg -i "$INPUT" -ss "$SS" -t "$T" "$TMP_NOISE_WAV"
sox "$TMP_NOISE_WAV" -n noiseprof "$TMP_NOISE_PRO"
ffmpeg -i "$INPUT" "$TMP_INPUT"
# remove noise (0.2-0.3 works well) and normalize (-1 to avoid clipping)
sox "$TMP_INPUT" "$TMP_OUTPUT" noisered "$TMP_NOISE_PRO" "$NR" norm "$N"
ffmpeg -i "$INPUT" -i "$TMP_OUTPUT" -c:v copy -map 0:v:0 -map 1:a:0 "$OUTPUT"
# clean up auxiliary files
rm "$TMP_NOISE_WAV"
rm "$TMP_NOISE_PRO"
rm "$TMP_INPUT"
rm "$TMP_OUTPUT"