.srt Subtitle Joiner

joiner.py

import re

duration_re = re.compile(r"^\d{2}:\d{2}:\d{2},\d{3} --> \d{2}:\d{2}:\d{2},\d{3}\n$")

with open('input1.srt', 'r', encoding='utf-8') as one, open('input2.srt', 'r', encoding='utf-8') as two, open('result.srt', 'w', encoding='utf-8') as out:
	one_lines = []
	line = one.readline()
	while line:
		while len(line) == 1:
			line = one.readline()
		idx = line
		line = one.readline()
		duration = duration_re.match(line)
		if not duration:
			print("[One] Break at duration:", line)
			break
		lines = []
		line = one.readline()
		while line and len(line) > 1:
			lines.append(line.strip())
			line = one.readline()
		one_lines.append((duration.group(0), '\n'.join(lines)))

	two_lines = []
	line = two.readline()
	while line:
		while len(line) == 1:
			line = two.readline()
		idx = line
		line = two.readline()
		duration = duration_re.match(line)
		if not duration:
			print("[Two] Break at duration:", line)
			break
		lines = []
		line = two.readline()
		while line and len(line) > 1:
			lines.append(line.strip())
			line = two.readline()
		two_lines.append((duration.group(0), '\n'.join(lines)))

	lines = one_lines + two_lines
	lines.sort(key=lambda item: item[0])

	index = 1
	for item in lines:
		out.write('{}\n'.format(index))
		out.write(item[0])
		out.write(item[1])
		out.write('\n\n')
		index += 1
	print("Done!")

Quick script for joining two .srt subtitles for a same clip. Sorted by time and indexes are recreated.