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Bilingual stacked subtitles for Belgian and Canadian theatrical release

By the Fonti Studio post-production team · 24 February 2026

In a Brussels cinema, the same print of an English-language film is read by two audiences at once. One reads the Dutch line. One reads the French line. They sit in the same room, watch the same frame, and the subtitle stack carries both.

That format has a name on the listings board. In Belgium it is written VOstBIL (or STBIL), the marker that tells a Brussels filmgoer the original version carries bilingual French and Dutch subtitles, so one screening serves both communities. In Switzerland it is written as a string of letters: E/d/f, English dialogue with German and French subtitles stacked one below the other. The notation is precise. Uppercase is the spoken language, lowercase is each subtitle track, and the order is the order they appear on screen. Zug's Kino Seehof publishes the exact key on its language versions page: "Upper-case letters denote the dialogue language, while lower-case letters indicate the language of the available subtitles."

For a distributor, the bilingual stack is not a stylistic choice. It is a contractual deliverable for a specific set of territories, and it has a format constraint that single-language work never hits. This piece is the working guide to it: what the file contains, how it renders, the one number that governs whether it is readable, and why we ship it as a free add-on when you buy the two single-language masters anyway.

The territories that ask for it

Three markets drive most bilingual-stack requests, for three different reasons.

Belgium is officially trilingual and functionally bilingual in Brussels, where Dutch and French speakers share the same cinemas. A release into the Brussels-Capital Region routinely runs both languages on one print so a single screening serves both communities. CINEMATEK, the Royal Belgian Film Archive housed in BOZAR, screens its programme in the original language, normally subtitled in French and Dutch. The bilingual stack is the default there, not the exception.

Switzerland runs the same model across its language regions. A film opening simultaneously in German-speaking and French-speaking cantons carries German and French subtitles together so one set of prints covers the country. The E/d/f marker exists precisely because the stacked, two-language subtitle is a standard Swiss arthouse and original-version release format.

Quebec is the regulated case, and the most consequential one for a distributor's calendar. Under Quebec's Cinema Act (C-18.1), a film cannot be shown to the public in a version other than French without a stamp from the director of classification, and the Act's section 83 sets out the routes to get one. A print carrying French subtitles can be stamped. Additional prints in a non-French version can be stamped only if the applicant files, with the application, a contract to produce a French-dubbed version of the film in Quebec within a time the director considers reasonable. Where no French-dubbed version exists yet, a provisional stamp runs 45 days from the film's first public commercial screening, and section 83.1 lets the director extend that period by up to fifteen days when a major, unforeseen impediment outside the holder's control blocks the dub. The dubbing obligation traces back to the 1983 Cinema Act, which first required English-language films to be made available in French within sixty days of release. The practical upshot for an English-language indie opening in Quebec is that the French-subtitled print is the legal entry ticket, and an English-and-French stack on that print serves both the anglophone Montreal audience and the regulator in one deliverable.

The pattern across all three is the same. The bilingual stack is not a nice-to-have. It is the format the territory is built around, and a distributor who shows up with two separate single-language files has shipped the wrong deliverable.

What is actually in the file

A bilingual stacked subtitle is one subtitle file, on one timing grid, with two lines per cue: one language on top, one underneath. For the Belgian case the convention is Dutch on the upper line, French on the lower. The cue starts and ends are shared. Both languages appear and disappear together, locked to the same speech onset and the same out point.

That is the whole trick, and it is also the whole problem. A normal subtitle cue has up to two lines and a per-line character budget to keep it readable. A bilingual stack spends both of those lines on two languages saying the same thing. There is no second line left for a long sentence to wrap into. Each language gets exactly one line, and the line has to hold the complete translation of the cue.

So the file is not "two subtitle tracks merged." It is a single track where every cue is already at its structural ceiling, and the localization work is to make two languages fit two single lines without either of them overflowing the screen.

The constraint that governs the whole format

Single-language broadcast subtitles cap the line at 42 characters and the cue at two lines. The bilingual stack inherits the 42-character line budget per language and spends the two-line allowance on the two languages. The cue duration is fixed by the speech, and reading speed still has to stay inside the 20-characters-per-second ceiling that broadcast and platform QC enforce, now measured against two lines of text that the eye has to scan in the same window.

That last point is the one most pipelines miss. A viewer reading a bilingual stack only reads one of the two lines, so the effective reading load per person is one language. But the cue still has to be authored so that each language, on its own single line, lands under the character budget and is legible in the time the cue is on screen. You cannot solve an overflow by wrapping to a third line, because the third line is the other language. You cannot solve it by splitting into two cues, because that desynchronizes the two languages from each other.

The only lever is the translation. Each language has to be condensed to fit one line of roughly 42 characters while preserving meaning, register and any locked glossary term. French re-orders and lengthens an English sentence; Dutch compounds and shortens it; the two languages overflow at different points on the same cue. The work is to bring both under budget on the same fixed duration, independently, without either reading like a telegram.

This is the same unit-level discipline a clean single-language master needs, applied twice on one cue with half the room. It is why a bilingual stack is not free to produce even when the two single-language translations already exist: a French line that was authored to use both subtitle lines has to be re-condensed to live on one.

A worked shape

Take a short exchange. In a single-language French master, a line of dialogue might author cleanly across two lines:

Tu crois vraiment qu'il va revenir
après tout ce qu'il a dit ?

Two lines, comfortably under budget, easy to read. In the bilingual stack, that French translation now has to collapse onto one line, because the second line belongs to Dutch:

Denk je echt dat hij terugkomt?
Tu crois vraiment qu'il revienne ?

Dutch on top, French underneath, each on a single line, each under the character budget, both gone from the screen at the same instant the actor stops speaking. The French had to lose "après tout ce qu'il a dit" to fit one line; a good condensation keeps the question and the doubt and drops the clause the picture already carries. Multiply that decision across every cue of a feature and you have the actual labour of a bilingual deliverable.

Why we ship it free with two masters

When a distributor buys a Dutch master and a French master from Fonti Studio for a Belgian release, the two translations already exist, locked to the same glossary, on the same cue clock, validated against the same broadcast spec. The bilingual stack is the re-condensation of those two into one single-line-per-language file. It is real work, but it is work on material we have already authored and already own the glossary for, so we do not bill it as a third language.

That is the policy: buy the two single-language masters for a bilingual territory, get the stacked version as a bonus. The glossary lock is what makes it cheap on our side. On our Kumite reference delivery, the French and Dutch masters were built from one 30-entry locked glossary, 1,212 cues per language, every cue under the 20 CPS ceiling. The stack draws on exactly that consistency: the same character name is spelled the same way on the Dutch line and the French line of every cue, because both came from the same canonical list.

Festival and accessibility releases

One more case sits next to the theatrical one. A festival or an accessibility-mandated screening sometimes asks for an SDH track and a bilingual stack, so that a deaf or hard-of-hearing viewer in a bilingual territory still gets sound description in their language. That is a denser file again: the non-speech cues (speaker IDs, sound events) localize into both languages and compete for the same two-line ceiling. It is doable on the same grid, but it is the tightest version of the format, and it is worth naming up front in the brief so the line budget is planned for from the first cue rather than discovered at QC.

If you have a feature heading into a Belgian, Swiss or Quebec theatrical window and the contract asks for a bilingual stack, we build it from the two single-language masters on one locked glossary, re-condensed to a single line per language and validated against the line and reading-speed budget before it ships. Send us the brief and the two target languages and we will tell you which cues are tight before you commit to the release date.

Fonti Studio is an AI-native subtitle and dubbing service for film distributors and sales agents. Broadcast-grade output validated on feature-length deliveries. €400 per language for subtitles, with the bilingual stack included when you buy two languages for a bilingual territory. Flat. EUR.