#!/bin/sh

# assign variables
filename=${1%%.*}
if [ -z "$2" ]; then language=nob; else language=$2; fi
if [ -z "$3" ]; then destination=.; else destination=$3; fi
stream=$(ffmpeg -i "$1" 2>&1 | awk -v lang="$language" -F"[#(]" '$0~lang {print $2}')
output_filename=$(printf %s/%s_%s.srt "$destination" "$filename" "$language")

# dump subtitle
ffmpeg -i "$1" -c copy -map "$stream" "$output_filename"

# remove empty file
if [ ! -s "$output_filename" ]; then rm "$output_filename" ; fi