This command line tool enables you to manually correct the timing of subtitles.
These corrections are permanent modifications to the subtitle files. This means they are not lost when playback ends, unlike media player corrections. This can be really useful for niche movies/series that don't have many correct subtitles.

Originally a rewrite of submod_py to learn Rust, it has since surpassed its Python ancestor in terms of features.

• If you do not have the Rust programming language installed on your system, install Rust first.

• Then, it's a simple install with cargo:

  git clone https://github.com/davidde/submod_rs.git
  cargo install --path ./submod_rs

submod 1.1.0
Modify the time encoding of .srt or .vtt subtitle files.
By default, submod generates a new output file, without overwriting the input.

USAGE:
    submod [FLAGS] [OPTIONS] <file> <seconds>

FLAGS:
    -o, --overwrite    Overwrite input file, destroying the original
    -O, --overname     Overwrite input file, renaming the original
                       (Only necessary on first call; consecutive `overnames` on same input
                       will NOT rename the input since this would overwrite the 'original' input)
        --srt          Convert to srt format
        --vtt          Convert to vtt format
    -h, --help         Prints help information
    -v, --version      Prints version information

OPTIONS:
        --out <filename>      Specify file name or path to store the output file
    -s, --start <hh:mm:ss>    Specify at what time the modification should start
    -S, --stop <hh:mm:ss>     Specify at what time the modification should stop
                              Use ':' to separate hours, minutes and seconds, like so:
                              hh:mm:ss to specify hours, minutes and seconds
                                 mm:ss to only specify minutes and seconds
                                    ss to only specify seconds

ARGS:
    <file>       File name or path to the subtitle file to modify
    <seconds>    Seconds by which to add or subtract the time encoding

• Delay all subtitles by 0.5 seconds:

  $ submod 'Humans S03E01 Episode 1.en.srt' +0.5
  Success.
   Output:   Humans S03E01 Episode 1.en__[+0.50_Sec+].srt

• To directly overwrite the input subtitle file, so you don't need to manually rename it, simply add the -o or -O flag:

  $ submod 'Humans S03E01 Episode 1.en.srt' +0.5 -o
  Success.
   The input file was overwritten.
   Output:   Humans S03E01 Episode 1.en.srt

  $ submod 'Humans S03E01 Episode 1.en.srt' +0.5 -O
  Success.
   The input file was renamed to `Humans S03E01 Episode 1.en__[Original].srt`.
   Output:   Humans S03E01 Episode 1.en.srt

• To display the subtitles 2 seconds earlier, starting from the 10th minute to the end:

  $ submod 'Humans S03E01 Episode 1.en.srt' -2 -s 10:00
  Success.
   Output:   Humans S03E01 Episode 1.en__[-2.00_Sec-].srt

  The second - sign in [-2.00_Sec-] indicates the file was only partially modified;
  this indicates the use of -s or -S flags. It will be + when those flags aren't used.