Fixing RTL texts before embedding in video as subtitles using ffmpeg

subtitle_rtl_fixer.py

#!/usr/bin/env python3
import pysrt
from sys import argv
from collections import Counter
import unicodedata as ud

# Function that detects the dominant writing direction of a string
# https://stackoverflow.com/a/75739782/10327858
def dominant_strong_direction(s):
    count = Counter([ud.bidirectional(c) for c in list(s)])
    rtl_count = count['R'] + count['AL'] + count['RLE'] + count["RLI"]
    ltr_count = count['L'] + count['LRE'] + count["LRI"] 
    return "rtl" if rtl_count > ltr_count else "ltr"

filename = argv[1]
subs = pysrt.open(filename)
for sub in subs:
    if dominant_strong_direction(sub.text) == "rtl":
        sub.text = "\u202b"+sub.text+"\u202c"

subs.save(filename, encoding='utf-8')