Merge two or more subtitles

merge_subtitles.py

#!/usr/bin/python3

"""
LPT: If your original subtitles are not .srt, convert them using ffmpeg
"""

import sys
import pysrt

def merge_subtitles(srts):
    head = """[Script Info]
ScriptType: v4.00+
Collisions: Normal
PlayDepth: 0
Timer: 100,0000
Video Aspect Ratio: 0
WrapStyle: 0
ScaledBorderAndShadow: no

[V4+ Styles]
Format: Name,Fontname,Fontsize,PrimaryColour,SecondaryColour,OutlineColour,BackColour,Bold,Italic,Underline,StrikeOut,ScaleX,ScaleY,Spacing,Angle,BorderStyle,Outline,Shadow,Alignment,MarginL,MarginR,MarginV,Encoding
Style: Default,Arial,16,&H00FFFFFF,&H00FFFFFF,&H80000000,&H80000000,-1,0,0,0,100,100,0,0,1,3,0,2,10,10,10,0
Style: Top,Arial,16,&H00F9FFFF,&H00FFFFFF,&H80000000,&H80000000,-1,0,0,0,100,100,0,0,1,3,0,8,10,10,10,0
Style: Mid,Arial,16,&H0000FFFF,&H00FFFFFF,&H80000000,&H80000000,-1,0,0,0,100,100,0,0,1,3,0,5,10,10,10,0
Style: Bot,Arial,16,&H00F9FFF9,&H00FFFFFF,&H80000000,&H80000000,-1,0,0,0,100,100,0,0,1,3,0,2,10,10,10,0

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text"""

    parts = [head.replace("\n", "\r\n")]

    items = []

    for i, file in enumerate(srts):
        srt = pysrt.open(file)
        for item in srt :
            item.style = "Top" if i==0 else "Bot"
            items.append(item)
    items.sort(key=lambda x: x.start.ordinal)

    for item in items:
        parts.append("Dialogue: 0,{start},{end},{style},,0000,0000,0000,,{txt}".format(
            start=str(item.start)[:-1].replace(",", "."),
            end=str(item.end)[:-1].replace(",", "."),
            style=item.style,
            txt=item.text.replace("\n", "\\N")
        ))

    print("\r\n".join(parts))

def usage():
    print('./merge-subtitles sub1_file sub2_file ... > out.ass')

def main():
    if len(sys.argv) < 3:
        usage()
    else:
        merge_subtitles(sys.argv[1:])

if __name__ == '__main__':
    main()