Adjust movie SRT based on two timestamps

adjust_srt.py

import pysrt


def srt_shift(shift, scale, input_file, output_file):
    
    ## the input srt file should be in utf-8 encoding

    subs = pysrt.open(input_file)
    print len(subs)

    subs.shift(seconds=shift)
    subs.shift(ratio=scale)

    subs.save(output_file, encoding='utf-8')
    
    print 'adjusted'
    
def strtime_to_sec(strtime='00:01:00,000'):
    
    import datetime
    import time
    x = time.strptime(strtime.split(',')[0],'%H:%M:%S')
    sec = datetime.timedelta(hours=x.tm_hour,
                       minutes=x.tm_min,
                       seconds=x.tm_sec).total_seconds()
                       
    return sec

if __name__ == '__main__':
    
    input_file ='movie.srt'
    
    output_file='movie_adjusted.srt'
    
    point1_now=strtime_to_sec('00:05:35,682')
    
    point1_true=strtime_to_sec('00:03:06,682')
    
    point2_now =strtime_to_sec('01:26:26,810')
    
    point2_true=strtime_to_sec('01:24:01,810')
    
    import numpy as np
    
    A=np.array([[point2_now,1],[point1_now,1]])
    
    B=np.array([point2_true,point1_true])
    
    scale, shift = np.linalg.solve(A,B).tolist()
    
    srt_shift(shift, scale, input_file, output_file)