rss logo

Python script to adjust srt/subtitles files

Python logo

It's quite common to have synchronization problems with subtitles files. Indeed, very often the subtitle file is not adapted to our source video file. So we usually have a delay that goes from a few milliseconds to a few seconds which can be quite annoying when playing.

It's possible, with most players (vlc, mpv or mplayer); see here; to adjust the delay, but the configuration will be lost at the next playback. So it is more interesting to be able to adjust by directly modifying the subtitle file.

I already developed a script in bash to do just that, but I wanted to do it in Python so here it is.

Usage

  • Usage :
user@host:~$ ./shebangthesubtitles.py [srt file] [+/- time]
user@host:~$ ./shebangthesubtitles.py -h
usage: shebangthesubtitles.py /movies/mysubtitle.srt -1.400

add/subtract delay on a srt file

positional arguments:
  file        srt file path
  delay       delay in seconds with 0.000 format

optional arguments:
  -h, --help  show this help message and exit
  • Subtract 400 miliseconds to subtitles :
user@host:~$ ./shebangthesubtitles.py /home/std/Running.on.Empty.1988.1080p.BluRay.x264.AAC.5.1-POOP.srt -0.400
  • Add 1.400 seconds to subtitles :
user@host:~$ ./shebangthesubtitles.py /home/std/Running.on.Empty.1988.1080p.BluRay.x264.AAC.5.1-POOP.srt 1.400
Note : The new srt file will be wrote in the same folder than source srt file with "_new.srt" suffix.

srt file format

  • This script has been built to work with this kind or srt files only :
[…]
1126
01:55:12,527 --> 01:55:14,461
I love you.

1127
01:55:20,735 --> 01:55:22,669
I really love you.

Code

#! /usr/bin/python

# Role : Add or subtract delay to a srt file
# Author : http://shebangthedolphins.net/
# 1.0 first version

import argparse
import re, sys
from datetime import datetime, timedelta
import shutil
from tempfile import mkstemp
from os import path

###START PARSER : https://docs.python.org/3/library/argparse.html
parser = argparse.ArgumentParser(description='add/subtract delay on a srt file',prog='shebangthesubtitles.py', usage='%(prog)s /movies/mysubtitle.srt -1.400')
parser.add_argument('file', help='srt file path')
parser.add_argument('delay', help='delay in seconds with 0.000 format')
args = parser.parse_args()
###END PARSER

###FUNCTION
def timeop (hours, minutes, seconds, milliseconds, delay):
        "function which add or subtract delayed time then return result"
        time_src = datetime(year=1983, month=12, day=12, hour=int(hours), minute=int(minutes), second=int(seconds), microsecond=int(milliseconds)).timestamp()
        result = time_src + delay
        return result

###CHECK ARGUMENTS
try:
        delay = float(args.delay)
except:
        print("Error, float argument needed.")
        parser.print_help()
        sys.exit(1)

if not path.exists(args.file):
        print("Error, file doesn't exist.")
        parser.print_help()
        sys.exit(1)


fs = open(args.file, 'r') #open srt file, read mode
fd, name = mkstemp() #returns a tuple containing an OS-level handle to an open file and the absolute pathname of that file, in that order.
fout = open(name, 'w') #open temp file, write mode
while 1:
        txt = fs.readline()
        if re.match(".*-->.*", txt): #if ".*-->.*" characters is in current line
                seq=txt.split(" --> ")
                hours_start, minutes_start, seconds_start = seq[0].split(":")
                hours_start = hours_start[-1:]
                seconds_start, milliseconds_start = seconds_start.split(",")
                milliseconds_start = int(milliseconds_start) * 1000
                new_start = timeop(hours_start, minutes_start, seconds_start, milliseconds_start, delay)

                hours_end, minutes_end, seconds_end = seq[1].split(":")
                hours_end = hours_end[-1:]
                seconds_end, milliseconds_end = seconds_end.split(",")
                milliseconds_end = int(milliseconds_end) * 1000
                new_end = timeop(hours_end, minutes_end, seconds_end, milliseconds_end, delay)

                txt = re.sub(seq[0], datetime.fromtimestamp(new_start).strftime('%H:%M:%S,%f')[:-3], txt)
                txt = re.sub(seq[1], datetime.fromtimestamp(new_end).strftime('%H:%M:%S,%f')[:-3], txt) + "\n"
                fout.write(txt) #write to tmp file
        else:
                fout.write(txt) #write to tmp file

        if txt == "":
                break
fout.close() #close tmp file
shutil.move(name, args.file.split(".srt")[0] + "_new.srt") #copy tmp file to srtfile_new.srt
fs.close() #close srt file
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Contact :

contact mail address