How to translate subtitles locally on a Mac, without uploading

You can transcribe, translate and export subtitles without any of your dialogue leaving your Mac. In cinemaOS the whole path lives in one place: Finisher ▸ Localize ▸ Captions. You transcribe the clip locally, fix words and speakers, choose a target language, press Translate Local, check the result side by side in Bilingual preview, run QC, and export SRT or another format, or burn the subtitles in.

This guide walks through every step and is honest about quality. Local translation is useful, but it is not a substitute for a native speaker on every language. cinemaOS tells you which languages need review before delivery.

Why translate locally

For unreleased films, interviews with vulnerable contributors, or client work under NDA, uploading a transcript to a cloud service is a real decision. Many editors would rather not make it.

In cinemaOS, no project, media, transcript or prompt is uploaded for AI. The network is used only for account, licence, checkout and updates. You can switch Wi-Fi off and do everything in this guide. Our article on on-device AI and privacy in video editing explains the trade-offs in more depth.

Before you start: cinemaOS runs on Apple silicon with macOS 15 or later. 8 GB of memory is supported; heavy AI jobs simply run one at a time.

Step by step in Localize ▸ Captions

Step 1: open Captions and transcribe

1. In the Sequencer, select the clip or sequence with speech.
2. Go to Finisher (⌘2) ▸ Localize ▸ Captions. You can also open HOME (⌘⇧H) and pick the Captions tile.
3. Set the spoken language to Auto Detect, or pick it if you know it. Picking it avoids misdetection on short clips or heavy accents.
4. Transcribe, or press ⇧⌘T for "Transcribe with J.A.R.E.D."

Transcription runs locally with bundled speech models (Parakeet, and Whisper for languages Parakeet does not cover). Speaker detection separates up to four speakers. If you are working from text-based editing, our guide to transcribing an interview and editing by text uses the same transcript.

Step 2: fix words and speakers before you translate

This is the step people skip, and it is the one that decides the quality of every language that follows. Any error in the source gets translated faithfully into every target.

• Names and places. Check every proper noun. Speech models guess at unusual names.
• Numbers, dates and units. Make them consistent in the source.
• Speakers. Where two people overlap or one speaker is labelled twice, merge or reassign. Four speakers is the detection limit, so larger panels need manual labels.
• Line breaks and timing. Split long subtitles at natural pauses. Translations often run longer than the source; a tight source line becomes an unreadable target line.
• Filler words. Decide now whether "um" and false starts stay. Removing them in the source keeps every translation cleaner.

A practical rule: watch the whole film once in Source view before translating anything.

Step 3: choose the target and read the tier chip

Type the target language, for example "French". Next to it, a tier chip shows how well the local model handles that language. cinemaOS offers 58 languages, each rated in one of three tiers:

• Good · spot-check. Dutch, French, German and Portuguese (Portugal). Output is generally solid; spot-check names, idioms and tone.
• Draft · review before delivery. Languages including Japanese, Spanish and Italian. Usable as a first pass that a fluent reviewer corrects.
• Rough · native review before delivery. Treat it as a starting point only. A native speaker should rewrite, not just proofread.

These tiers come from measurements, and they are shown on purpose. Translation runs on a single bundled on-device model with no cloud fallback. It is honest to say that only four languages are rated Good today.

Step 4: translate with Translate Local

Press Translate Local. Translation runs in chunks, so you can follow progress and cancel at any time. If you stop or quit, Resume translation picks up where it left off instead of starting again.

On an 8 GB Mac, other heavy AI jobs wait their turn, so start long translations before a break rather than in the middle of a grade.

Step 5: review in Bilingual preview

Switch the view between Source, Translation and Bilingual. Bilingual shows both languages together over the picture, which is the fastest way for a reviewer who reads both to catch:

• meaning that drifted, especially jokes, idioms and irony;
• names that were translated when they should not have been;
• formality that is wrong for the speaker (tu or vous, du or Sie);
• lines that are now too long to read in the time on screen.

If your reviewer does not use cinemaOS, export the translation as SRT and send it with a review copy of the picture. Keep the corrected source transcript safe so you can translate again after picture changes.

Step 6: run QC, then export or burn in

Before export, choose a QC profile that matches where the file is going, and run it. The checks that matter most are the usual ones: reading speed, line length, overlapping cues and timing. Then pick a mode:

• Strict when a platform publishes hard rules and you want to see every problem before you decide how to fix it;
• Compatible Repair when the goal is a file that plays cleanly on as many players as possible.

Then export. cinemaOS writes SRT, WebVTT, ASS, SCC, EBU-STL, iTT, IMSC1, EBU-TT-D and FCPXML. If you are unsure which a platform needs, see subtitle formats explained. For screenings, social posts or any player that ignores sidecar files, use Burn In to render the subtitles into the picture as a new deliverable.

A short checklist before delivery

1. Source transcript corrected and watched in full.
2. Speakers labelled, overlaps resolved.
3. Target language tier noted; Draft and Rough reviewed by a fluent or native speaker.
4. Bilingual pass done with picture.
5. QC run with the profile the platform expects.
6. Correct format exported, file named with the language code.
7. A burned-in copy made only where a sidecar will not work.

FAQ

Does this work with no internet connection?

Yes. Transcription, translation, QC and export all run on the Mac. cinemaOS only needs the network for account and licence checks, and it works offline for up to seven days between checks.

Which languages can I deliver without a reviewer?

None, strictly. Even the Good tier (Dutch, French, German, Portuguese (Portugal)) should be spot-checked. Draft and Rough languages need a fluent or native review before delivery.

How long does local translation take?

It depends on the length of the film, the language and your Mac. Translation runs in chunks with visible progress, and you can cancel and use Resume translation later, so a feature does not have to be done in one sitting.

Try it on your own film

Take one scene, switch off Wi-Fi, and run the full path from Auto Detect to a QC-checked SRT. Download cinemaOS and use the 60-day free trial; no card is required.