Resynchronize subtitles

Summary

Desynchronization types

There are several desynchronization types.

Constant gap
In this case, subtitles are all shifted of the same value. Current timing A and correct timing C are linked by the the formula C = A + K, where K is a constant. This case appears for example when parts of the video are added or removed. The subtitles following he addition or removal are then all shifted of the added or removed part duration.
Affine gap
In this case, subtitles gap increases or decreases constantly with the time. Current timing and correct timing are linked by the formula C = K1 * A + K2, where K1 and K2 are constants. This case appears for example when subtitles beginning and end are based upon the video frames instead of time : changing the video framerate will desynchronize the subtitles.
Non-linear gap
Here, the subtiles gap does not match one of the formulas above. Subs Factory is not able to treat these cases. You will have to do it part by part, as if each part had a constant or affine gap. This is happily a rare case.

Choosing reference subtitles

Start by opening a .srt or .sub file to be resynchronized within Subs Factory.

Then, choose two subtitles for whose you know the correct timing, and that are part of the subtitles to resynchronize. Resynchronization will be more accurate if you choose them as far apart as possible. Take for example the first and last subtitles to resynchronize. Remember their number. Then, place one marker for each of them : either a "In" marker where the subtitle should begin, or an "Out" marker where it should end.

Resynchronization window

Get to the "Actions" palette of the concerned subtitles file. Click on the "Resynchronize" button. The following window should appear :

The two first fields allow to choose the subtitles to be resynchronized by entering the number of the first and the last to be. You also can select the subtitle in the main window (eg. with the subtitles table) to make it current, and click on the "Current" button located beside the field to fill. Anyway, the beginning of the subtitle will appear greyed below, as a confirmation. The "All" button allows to select all the subtitles of the file to be resynchronized.

The second part allows to indicate the gap for each reference subtitle choosed. This gap will be interpolated to every subtitle to be resynchronized. Enter their number, or use the "Current" button to choose them. Then, select the markers where they should be.

The checkbox allows to disable the choice of the second subtitle : it is optional in case of a constant gap.

Finally, click on the "Resyncronize" button to launch resynchronization. To close this window without resynchronizing, use the "Resynchronize" button of the "Actions" palette that you used to open this window, it turned into a "Cancel" button.