Option to split subtitles at “logical” points

[TB54]

Hello,
I've been using Subtitle Edit for some time now, and it's an exceptional freeware that has saved me a lot of time! Thanks very much for it.

There is only one option that is a problem me: the one that allows you to split subtitles in two. Unless I'm mistaken (maybe I missed an option?), this splitting is done solely on the basis of the number of characters. As a result, the two resulting subtitles almost always need to be re-written: the cut is made in the middle of a sentence segment, or even in the middle of a noun and its adjective, etc.

Would it be possible to include an option that cuts sentences at more logical points? For example, that would make that the split is preferably made:

• At a comma, period, or hyphen (in the sentence "That's great, we could indeed to that" it would be better to insert the cut at "That's great, / we could indeed to that")
• At the end of a phrase segment (for example, in the sentence “He is a bad man who has done a lot of harm”, it would be better to insert the cut at “He is a bad man / who has done a lot of harm”)

The same option could be used for breaking a line into two (decide which part of the sentence to put on the second line).

I am well aware that the second option (cutting according to sentence segments) would require integrating the logic of different languages, which is undoubtedly complicated. But perhaps it would be possible to integrate the first option?

[yolestat]

Feature Request: Smart subtitle splitting using sentence punctuation with proportional timing

Summary

I would like to suggest adding an optional feature to improve subtitle splitting when working with long subtitles, especially those generated by speech-to-text engines such as Whisper, Faster-Whisper, WhisperX and similar tools.

The current splitting algorithm does a good job of balancing subtitle lengths, but it does not always preserve natural sentence boundaries. This often requires manual correction after transcription.

Proposed option

Add a new checkbox in Tools → Split long lines:

☐ Prefer sentence punctuation when splitting subtitles

When enabled, Subtitle Edit would first try to split subtitles at sentence-ending punctuation before applying the standard balancing algorithm.

Supported punctuation could include:

• .
• ?
• !
• ...
• …

Optionally, secondary punctuation such as ; or : could also be considered if no sentence-ending punctuation is available.

Suggested algorithm

When a subtitle exceeds the configured limits:

1. Search for a suitable sentence-ending punctuation mark.
2. If multiple candidates exist, select the one that produces the most balanced subtitle durations.
3. If no appropriate punctuation is found, fall back to the current splitting algorithm.

This ensures that the current behavior is preserved whenever no natural split point exists.

Timing distribution

The timing should not simply be divided equally.

Instead, the original subtitle duration should be redistributed proportionally according to the amount of spoken content (characters, words, or another suitable metric).

Example:

Original subtitle

00:00:00,000 --> 00:00:06,000

I don't know what happened yesterday. Everything changed after dinner.

Result

00:00:00,000 --> 00:00:03,100

I don't know what happened yesterday.

00:00:03,100 --> 00:00:06,000

Everything changed after dinner.

This preserves both the natural sentence structure and realistic subtitle timing.

Benefits

• Produces more natural subtitles.
• Preserves complete sentences.
• Reduces manual editing after AI transcription.
• Improves readability.
• Works especially well with speech-to-text generated subtitles.
• Completely backward compatible, since the option would be disabled by default.

I believe this small optional feature would significantly improve Subtitle Edit's workflow for users working with modern AI transcription engines while leaving the current behavior unchanged for everyone else.

Thank you for considering this suggestion.