This overview explains how Fluen Studio turns a raw transcript into subtitles, and what the Subtitle splitting options in your workspace settings do: Auto (Recommended), Standard and Smart.
Automatic subtitles are made in several steps, each with its own job. One of the most important, and often the least visible, is subtitle splitting, also called segmentation.
After a transcription engine has turned the speech into text, Fluen splits that text into subtitles. This step is ours, whichever engine produced the transcript. It decides where each subtitle starts and ends, how the text is divided across one or two lines, and how long each subtitle stays on screen, following professional subtitling standards.
In practice, splitting is what makes subtitles feel natural to read rather than awkward and tiring, especially in long-form, pre-recorded media.
Splitting is where subtitles truly take shape.
The options in your workspace
You find them in Workspace Settings, Subtitle Defaults, under Subtitle splitting in the Engines card. Most workspaces never change it.
- Auto (Recommended): picks a method by file length and language. This is the default.
- Standard: fast, grammar-aware line breaks.
- Smart: follows meaning across sentences, and is slower.
- Legacy: our previous method, no longer recommended. It is only listed for workspaces that still use it.
Standard and Smart compared
| Standard | Smart | |
|---|---|---|
| How it works How subtitle breaks are chosen |
Language-specific grammar models | AI language understanding |
| Language support Which languages are covered |
☆☆ Languages with a dedicated grammar model |
All supported languages |
| Subtitle readability How natural subtitles feel |
Very high |
☆ High |
| Professional style rules Netflix / BBC-style conventions |
Fully applied |
☆ Applied where possible |
| Mixed-language speech Formatting when speakers switch languages |
☆☆ Good |
☆ Very good |
| Speed | Fast | Slower |
| Asian languages | ✔ Yes (dedicated word splitting) |
✔ Yes |
| Text cleanup & formatting Numbers, units, rewriting |
✔ Yes | ✔ Yes |
| AI Wordsmith on translations | ✔ Yes | ✔ Yes |
| Best for | Style-guide quality subtitles in the major languages, and long files | Every other language, and mixed-language speech |
How Auto decides
Auto chooses for each file, based on its length and its language:
- Files of an hour or more always use Standard, which is fast and dependable at any length.
- Shorter files use Standard in the languages where its grammar models tested better than or as well as Smart: English, French, German, Italian, Spanish, Portuguese, Dutch, Danish, Swedish, Norwegian, Polish, Czech, Romanian, Russian and Ukrainian, including their regional variants.
- Shorter files in other languages use Smart, which covers every language.
As our grammar models improve, Auto moves more languages to Standard. Several were added in 2026, after our tests showed Standard matching or beating Smart on line-break quality for them.
Standard
Standard is built on Natural Language Processing models made for each language. It follows that language's grammar to decide where subtitles should break, so it avoids splitting text in awkward places: separating a first name from a surname, an article from its noun, or a verb from its subject.
This closely follows professional subtitling guidelines such as those used by Netflix and the BBC, which makes it especially suitable for polished, long-form content. For Chinese, Japanese and Thai, which are written without spaces between words, it uses dedicated word splitting.
Smart
Smart uses large language models to judge where the text can be split without hurting readability. It works in every language Fluen supports, including those without a dedicated grammar model, and it can follow the meaning across sentences.
That flexibility helps with edge cases, especially when language structure varies or several languages appear in the same sentence. If speakers move between languages mid-sentence, Smart usually produces more coherent breaks than a strictly rule-based approach. The trade-off is speed: Smart takes longer than Standard.
Shared by both: AI Wordsmith
Both methods work with AI Wordsmith, the step that runs automatically during translation and adapts the translated text when:
- It becomes too long for the time the subtitle is on screen
- Reading speed limits would be exceeded
- A literal translation hurts readability
It rephrases or condenses the line so it fits, keeping the meaning, just like a professional subtitler would. AI Wordsmith applies to translations only. Captions remain verbatim by design.
Standard and Smart both break lines in natural places, so words that belong together stay together, and both keep subtitles with a lot of text on screen a little longer when there is a pause.
Should you change the setting?
Usually not: Auto already picks the better method for each file. Some cases where pinning one can make sense:
Educational and training videos in a major language
You are subtitling a recorded course, internal training or webinar, and viewers will read subtitles for long stretches.
Good choice: Standard (which Auto already uses for these languages). It gives the cleanest reading experience and follows professional subtitle standards closely.
Multilingual or mixed-language recordings
Speakers switch languages mid-sentence, or use foreign terms often.
Good choice: Smart. It handles code-switching more gracefully and avoids awkward breaks caused by rigid grammar rules.
Less common languages
You need subtitles in a language without a dedicated grammar model.
Good choice: Auto or Smart. Smart covers every language while still producing readable, well-timed subtitles.
If you want different line lengths on a track that already exists, you do not need to change this setting: the Rules button in the editor re-splits the track in seconds, at no cost.
What actually makes subtitles readable
Transcription gives you the words. Splitting decides how those words are read.
By offering both Standard and Smart, and picking between them automatically, Fluen AI keeps subtitles readable and professional whatever the language or the content.
Whether you need strict style-guide compliance or maximum flexibility across languages, Fluen Studio gives you control over the step that most directly shapes the viewer's experience.