MKV DTS to AC3 Converter

#!/usr/bin/python
# -*- coding: utf8 -*-
# This script converts all DTS streams inside an MKV to AC3 and adds them to the MKV file
# The newly generated MKV is stored in the target directory

# Import module OS
import os, sys

param_count = len(sys.argv)

if param_count == 1:
  print "mkvdts2ac3 - The DTS / DTS-HD to AC3 converter"
  print
  print "Usage: mkvdts2ac3 /path/to/my.movie.mkv"
  quit()

# Get source MKV from MKV
source_mkv = sys.argv[1]

# Target MKV = source MKV filename plus output path
target_mkv = source_mkv[:-3] + "AC3.mkv"

# Get FPS of source MKV
mkvinfo = os.popen ("mkvinfo " + source_mkv)

fps = ""
video_track = 0

for info in mkvinfo:
  if info.find ("Tracktyp: video") <> -1:
    video_track = 1

  if video_track and info.find ("Standarddauer:") <> -1:
    fps = info
    video_track = 0

fps = fps.split("(")[1].split(" ")[0].strip()

# Get track information of source MKV
tracks = os.popen ("mkvmerge -i " + source_mkv )

track_count = 1

ac3_tracks = []

# Loop through all tracks
for track in tracks:
  # Only process strings with "Track ID" in them
  if track.find ('Track ID') <> -1:
    # Remove whitespaces
    track = track.strip()

    # Extract AC3 streams
    if track.find ('A_AC3') <> -1:
      extension = 'ac3'
      extract_command = "nice -n 19 ionice -c3 mkvextract tracks " + source_mkv + " " + str (track_count) +":/tmp/Track_" + str (track_count) + "." + extension
      print extract_command
      os.popen ( extract_command )
      # Remember generated AC3 stream for later remuxing
      ac3_tracks.append ("/tmp/Track_" + str (track_count) + ".ac3")

    # Extract DTS / DTS-HD and convert to AC3
    if track.find ('A_DTS') <> -1:
      extension = 'dts'
      # Extract DTS / DTS-HD stream from MKV
      extract_command = "nice -n 19 ionice -c3 mkvextract tracks " + source_mkv + " " + str (track_count) +":/tmp/Track_" + str (track_count) + "." + extension
      print extract_command
      os.popen ( extract_command )
      # Convert DTS / DTS-HD stream to 6 channel AC3
      convert_command = "nice -n 19 ionice -c3 ffmpeg -i " + "/tmp/Track_" + str (track_count) + "." + extension + " -acodec ac3 -ac 6 -ab 448k /tmp/Track_" + str (track_count) + ".ac3"
      print convert_command
      os.popen ( convert_command )

      # Remember generated AC3 stream for later remuxing
      ac3_tracks.append ("/tmp/Track_" + str (track_count) + ".ac3")

      # Clean up converted DTS / DTS-HD stream
      os.remove ("/tmp/Track_" + str (track_count) + "." + extension)

    # Increase track count
    track_count = track_count + 1

cl = ""

# Generate list of all available AC3 files for remux
for ac3_track in ac3_tracks:
  cl = cl + " " + ac3_track

# Merge generated AC3 streams with old MKV (without any audio) to new MKV
command = "mkvmerge -o " + target_mkv + " --no-audio " + source_mkv + " " + cl
print command
os.popen (command)

# Clean up temporary generated AC3 tracks
for ac3_track in ac3_tracks:
  os.remove (ac3_track)