Extract subtitles from video and format them to SRT spec

srtextract.sh

#/bin/sh
#
# Extract subtitles from video and format them to SRT spec
# Useful for Samsung Smart TVs
#
# Depends on mkvtoolnix package (available for most distros) for mkvmerge and mkvextract
# To list tracks in the video, use command: ./srtextract.sh tracks <filename>
#
# Depends on ass2srt.pl for susbtitle format conversion
# http://code.google.com/p/ass2srt/downloads/list
#
if [ -z "$1" ]; then echo "Error: Video filename required as first argument."; exit 0;
elif [ "$1" = "tracks" ]; then
	if [ -z "$2" ]; then echo "Error: Video filename required as second argument."; exit 0;
	else mkvmerge -i $2;
	fi
else 
	if [ -z "$2" ]; then
		echo "No subtitle track number specified, extracting first one found..."
		subtrack=$(mkvmerge -i $1 | grep subtitles | awk -F" " '{print $3}')
	else
		subtrack="$2:"
	fi
	subfile=${1%.*}.english.ass
	mkvextract tracks $1 $subtrack$subfile
	perl ass2srt.pl $subfile
	rm $subfile
	perl -pi -0 -w -e "s/\n\n\n+/\n\n/g" ${subfile%.*}.srt
fi
# validate with https://github.com/smelc/srtcheck