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srttiming is a tiny command-line application which converts pace and offset of .SRT subtitle files among different frame rates.

srttiming converts ALL the time labels in the original .srt file according to given PACE and OFFSET values.

srttiming can also calculate PACE and OFFSET values from given REFERENCE TIME POINTS.

Currently intended for Linux/Unix platforms.

Help screen is as follows :

srttiming is a command line application
          which converts pace and offset of .SRT subtitle files among different frame rates

srttiming {   { -c coefficient offset } | 
            | { -t|-tl current_srt_time_1 current_srt_time_2  actual_time_1 actual_time_2} 
            | { -f srt_frame_rate movie_frame_rate } 
          } 
          [input_file_name [output_file_name]]

  where :
     -c is direct coefficient and offset usage with 2 parameters :
           coefficient is the pace of the subtitles
                   its value is  multiplied 
                   by the original time value (from the input .srt file) 
                   coeffcient should be greater than 0
                   if the coefficient is greater than 1.0 then the pace of the subtitles decrease
                   if the coefficient is less than 1.0 then the pace of the subtitles increase
                   it is wise to specify at least 5 digits after the floating point
                   e.g. 1.00235  or 0.99967
                      a precision loss of 0.001 will result in a gap of 1 second
                      within 16 minutes and 40 seconds of playtime
                      a precision loss of 0.0001 will result in a gap of 1 second
                      within 166 minutes of playtime

           offset is the value in seconds that will be added to 
                   coefficient*original_time
                   Threfore 
                       resulting_time = coefficient * original_time + offset
                     e.g. 
                       coefficient    = 0.9561
                       offset         = -0.25
                       original_time  = 25:18,700
                     then 
                       resulting_time = 24:11,779

     -t is calculation of coefficient and offset values from 4 reference time points
               the longer time period  between the reference time points 
               yields to more accurate calculation
           current_srt_time_1 is the first reference point in the current subtitle (.srt) file
           current_srt_time_2 is the second reference point in the current subtitle (.srt) file
           actual_time_1      is the actual time in the movie where current_srt_time_1 should have been
           actual_time_2      is the actual time in the movie where current_srt_time_2 should have been
           format :
              all the parameters are in "hours:minutes:seconds,milisecons" format
              e.g.  02:44:21,389

     -tl is the same as -t except it only displays calculated coefficient and offset values and exits

     -f is calculation of coefficient from the frame rates of the subtitle (.srt) file  and the movie
               offset is always assumed as 0.0
           srt_frame_rate is the assumed frame rate of the subtitle(.srt) file
           movie_frame_rate is the frame rate of the actual movie
                  e.g.
                     -f 23.98 24
                          would increase the pace of the subtitle by the coefficient value of 0.999166
                     -f 25 24
                          would decrease the pace of the subtitle by the coefficient value of 1.041666

     input_file_name is the original SRT file
                 specify as "-" for standard input
                 default input file is standard input
     output_file_name is the resulting SRT file
                 default output file is standard output

  examples : 
          srttiming -c 1.0025 -0.58 old.srt new.srt
          srttiming -t  00:04:21,0 02:44:00,0 00:04:22,0 02:46:36,0 old.srt new.srt
          srttiming -tl 00:04:21,0 02:44:00,0 00:04:22,0 02:46:36,0
          srttiming -f 25.0 23.976 old.srt new.srt

  note :  That help info is printed to "stderr",
          in order to redirect the output to "stdout" use "2>&1"  in bash shell
           e.g.  
              srttiming 2>&1 | more

Author :  Ozgur Urgenc 2018

Programmed in C .

Project Members:

• ozgur urgenc (admin)