extract a DTS track from an MKV, convert it to FLAC, remux into new MKV w/ additional FLAC track, and set FLAC as default audio track

dts-to-flac.sh

#!/bin/bash

for ((i=1; i<=13; i++)) do
  if [[ "$i" -ge 10 ]]; then
    name=$(ls The\ Expanse\ -\ S02E$i*.mkv)
  else
    name=$(ls The\ Expanse\ -\ S02E0$i*.mkv)
  fi

  # extract out dts track (id: 1 all files)
  dtsfile="s02e${i}.dts"
  mkvextract "${name}" tracks 1:${dtsfile}

  # convert dts track to FLAC
  ffmpeg -acodec dts -i "$dtsfile" -vn -sn -acodec flac "s02e${i}.flac"

  mv "$name" s02e${i}.mkv

  # add FLAC track to original mkv
  mkvmerge -o "$name" s02e${i}.mkv s02e${i}.flac
  # set FLAC track (3rd audio track) language as english
  mkvpropedit "$name" --edit track:a3 --set language=eng
  # make FLAC track default audio track
  mkvpropedit "$name" --edit track:a1 --set flag-default=0
  mkvpropedit "$name" --edit track:a3 --set flag-default=1

  # cleanup
  for ext in dts flac mkv; do
    rm s02e${i}.${ext}
  done
#  if [[ "$i" -eq 1 ]]; then
#    echo "stopping after $i"
#    exit
#  fi
done