Add or Remove delay to some SubRip file format (.srt).

fix_sub_delay.py

#!/usr/bin/python
"""
    fix_sub_delay.py:
        Add or Remove delay to some SubRip file format (.srt).
    @author [email protected]
"""
import sys
import os
import re
from datetime import datetime, timedelta

if len(sys.argv) < 3:
    print('Expected args <millis to sum> <path to file>')
    sys.exit(1)

ts_pattern = '%H:%M:%S,%f'
millis_to_sum = sys.argv[1]
filename = sys.argv[2]
file_dir = os.path.dirname(os.path.abspath(filename))


def parse_time(s):
    return datetime.strptime(s.strip(), ts_pattern)


def add_millis(date):
    time = parse_time(date)
    time = time + timedelta(milliseconds=int(millis_to_sum))
    return time.strftime(ts_pattern)


def add_timestamp(ts):
    begin, end = [add_millis(x) for x in ts.split('-->')]
    # remove the last three numbers of the timestamp
    return begin[:-3] + ' --> ' + end[:-3]


def main():
    counter = 1
    timestamp = False

    f = open(filename, 'r')
    output = open(os.path.join(file_dir, 'output.srt'), 'w')

    for line in f:
        print(counter, 'line', repr(line))
        
        if timestamp:
            new_line = add_timestamp(line)
            output.write(new_line + '\n')
        else:
            output.write(line)

        # Check if the next line will be a timestamp
        regex = "^%s\\s+$" % (counter)
        pattern = re.compile(regex)
        if pattern.match(line):
            counter += 1
            timestamp = True
        else:
            timestamp = False

    # Close resources
    f.close()
    output.close()
    print('Total parsed lines: ', counter-1)

main()