How to synchronize subtitles with Subtitle Composer?

I know how to do that with Gnome Subtitles:

• opening the subtitle and the video

• pausing video when the proper subtitle line is selected

• adding a sync point at the beginning and at the end

This fixes the subtitle in 70% of cases. Adding 2-3 more intermediary points brings that to 95%.

In KDE I would prefer to use Subtitle Composer, which is Qt/KDE tool. It has many other advantages. It seems lighter, richer, with better video rendering (scrolling video is awful in Gnome Subtitles). It is cross-platform, and in Linux is also available as Appimage.

All I could find found about synchronizing with this tool is:

Quick and easy subtitle sync:

Dragging several anchors/graftpoints and stretching timeline
Time shifting and scaling, lines duration re-calculation, framerate conversion, etc.
Joining and splitting of subtitle files

But what exactly are the steps to sync a subtitle with this tool?

What steps are the equivalent of those taken in Gnome Subtitles?

Edit:

Sometimes this simple trick works: select the subtitle line that you need to synchronize with a line in the movie, stop the movie at that moment, and press Shift-A (or Times - Shift to video position) and save.

But in most cases it's not enough.

The quickest/easiest method to sync subtitle with Subtitle Composer is:

1. select a title near the video start and press Alt+A (Menu - Times > Toggle Anchor)
2. drag that anchored title to correct position on waveform
3. select one title near the video end and anchor this one too with Alt+A (keep first one anchored too)
4. drag second anchored title to correct position

That should be enough for synchronizing most titles as they are usually linearly distorted - otherwise keep repeating steps 3 and 4 on other titles which are off.

At some point there will be ability to sync titles using speech recognition in SC, but not yet.

I do not have a Subtitle Composer, but I would use a command prompt editor subs.

It is a very good program for shifting, streching, moving and splitting subtitles. Command prompt:

subs - convert, join, split, and re-time subtitles

If subtitles are shown too early ( 5 seconds):

subs -i -b 5 file.sub

If subtitles are for a movie in 25 fps, need to be for 24 ( actual for frame-based formats only ).

subs -i -a 24/25 file.sub

If subtitles start ok, but in 1 hour are late in 7 seconds:

subs -i -p 0 0 -p 1:00:00 +7 file.sub

Join two parts with 15-second gap

subs -o joined.sub -j 15 part1.sub part2.sub

The source is here:

 https://metacpan.org/release/Subtitles

installation is not automatic, but works ok.

It should be in Cannonical, but I do not know where and how to apply... (I am not an author)