Simple script to fix the reversed dialogue in HorribleSubs's april fools subs. Correctly handles UTF-8 text and remuxes into a new MKV.

fix-horriblesubs-april-fools.py

#!/usr/bin/env python3

import re
import sys
import subprocess
import hashlib
import os

DEBUG       = False

MKVEXTRACT  = 'mkvextract'
MKVINFO     = 'mkvinfo'
MKVMERGE    = 'mkvmerge'

md5sum = lambda text: hashlib.md5(text.encode('utf-8')).hexdigest()

def get_sub_track_id(filename):
    return 2

def extract_subs(filename):
    track_id = get_sub_track_id(filename)
    new_filename = '%s.ass' % md5sum(filename)
    subprocess.call([MKVEXTRACT, 'tracks', filename, '%d:%s' % (track_id, new_filename)])
    return new_filename

def merge_subs(source_filename, sub_filename):
    new_filename = source_filename + '.fixed'
    subprocess.call([MKVMERGE, '-o', new_filename, '-S', source_filename, sub_filename])
    #os.unlink(sub_filename)
    return new_filename
    
def reverse_subs(source, dest):
    with open(source, 'r', encoding='utf-8') as sf:
        with open(dest, 'w', encoding='utf-8') as df:
            for line in sf:
                if line.startswith('Dialogue:'):
                    parts = line.strip().split(',', 9)
                    line = ','.join(parts[:-1] + [parts[-1][::-1] + '\n'])
                df.write(line)
            df.flush()
    return

if __name__ == '__main__':
    source_file = sys.argv[1]
    
    sub_file = extract_subs(source_file)
    fixed_sub_file = sub_file + '.fixed'
    reverse_subs(sub_file, fixed_sub_file)
    fixed_file = merge_subs(source_file, fixed_sub_file)
    sys.stdout.write('%s => %s' % (source_file, fixed_file))

    if not DEBUG:
        for fn in [sub_file, fixed_sub_file]:
            os.unlink(fn)