mkvtomp4.sh

#!/bin/bash
filedir=$1;

echo "Starting converstion to mp4 script"
if [ -d "$filedir" ]; then
  cd "$filedir"

  for file in ./* ;
  do
    if [[ $file = *.mkv || $file = *.avi ]] ; then
      if [[ $file == *","* ]] ; then
        newfile=${file//,/}
        mv "$file" "$newfile"
        file="$newfile"
      fi
      file=${file##*/}
      donefile=${file:0:${#file}-4}".mp4"

      ############################
      # First, extract subtitles #
      ############################
      # Find out which tracks contain the subtitles
      if [[ $file = *.mkv ]] ; then
        mkvmerge -i "$file" | grep 'subtitles' | while read subline
        do
          # Grep the number of the subtitle track
          tracknumber=`echo $subline | egrep -o "[0-9]{1,2}" | head -1`

          # Get base name for subtitle
          subtitlename=${file%.*}

          # Extract the track to a .tmp file
          echo "Extracting subtitles for file: $file"
          `mkvextract tracks "$file" $tracknumber:"$subtitlename.srt.tmp" > /dev/null 2>&1`
          `chmod g+rw "$subtitlename.srt.tmp"`

          # Do a super-primitive language guess: ENGLISH
          langtest=`egrep -ic ' je | tu | le ' "$subtitlename".srt.tmp`

          # Check if subtitle passes our language filter (10 or more matches)
          if [ $langtest -ge 10 ]; then
            `mv $subtitlename.srt.tmp $subtitlename.srt`
            `chmod g+rw "$subtitlename.srt"`
          else
            `rm "$subtitlename.srt.tmp"`
          fi
        done
      fi

      # Wait while any other ffmpeg processes are running
      while [ -n "$(ps -ef | egrep "ffmpeg" | grep -v grep)" ];
      do
        echo -e "\n[$(date +%b\ %d\ %Y:\ %H:%M:%S)]\nFound another instance of ffmpeg running, pausing 5 minutes..."
        sleep 300
      done

      # ffmpeg cmd
      /usr/local/bin/ffmpeg -i "$file" -c:v copy -c:a libfdk_aac "$donefile"

      if [ -f "$donefile" ]; then
        rm "$file"
      fi
    fi
  done
fi

exit 0