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DubSync
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Online course translation

Translate your online course. Same lessons, same teacher, a new language.

DubSync dubs the lecture videos of a course, which is the spoken part of e-learning localization. To translate a course to Spanish or any of 27 other languages, upload each lesson as a video file and get back an MP4 in a voice created from your own. Slides, worksheets, quizzes and captions are not part of the dub.

Upload a lesson

Pro: 7 days free for eligible new subscribers, with 60 minutes. Card required. Then $29.90/month; cancel before the trial ends to pay nothing. Trial minutes expire after 7 days.

Upload an MP4, MOV or M4V. You see the minutes and the cost before anything starts.

EnglishOriginal

What is said: Welcome to lesson one. I teach in English and my students abroad hear this course in their own language.

What is said: Bienvenidos a la lección uno. Yo enseño en inglés y mis estudiantes en el extranjero escuchan este curso en su propio idioma.

What is said: Bem-vindo à lição um. Eu ensino em inglês e meus alunos no exterior ouvem este curso em sua própria língua.

Demo clip: an AI-generated scene with a fictional character. Dubbed with VDub v2, the model DubSync runs; lip-synced tracks use VSync v2.

Lip-sync shown in these examples is an optional paid add-on, separate from the dubbing trial.

What gets translated

E-learning localization has several parts. DubSync does the lecture audio.

A full e-learning translation service covers videos, slides, quizzes, captions and platform setup. DubSync is a tool for one line of that list: what you say in the lessons.

Inside the dub

  • Everything you say in the lecture, in a voice created from yours. Similar, not identical.
  • Guest lecturers and co-instructors: each speaker gets their own voice.
  • Intro music and background sound, kept under the new speech.
  • One dubbed MP4 per lesson, with no visible watermark.

Still on your list

  • Text on slides, in screen recordings and in code samples. A dub changes the audio only.
  • Worksheets, workbooks, downloads and quiz questions.
  • Interactive modules, such as SCORM packages built in an authoring tool. DubSync takes video files only, so you export each video and put the dubbed MP4 back yourself.
  • Captions and transcripts. DubSync doesn't make subtitle files. Udemy adds subtitles in the teaching language itself for courses taught in seven languages, Spanish and Portuguese among them, once a course has 20 or more marketplace enrollments. Language-learning courses are excluded.1
  • The sales page, lesson titles, emails and student support.

Why lectures dub well

One teacher, one microphone, one lesson at a time.

Hear a lesson change language

A dub is built from what the microphone heard. A typical lesson is one person speaking clearly, close to the microphone, with nobody talking over them. That is the kind of recording a dub handles well.

Play this lesson in its original Spanish, then switch the language. It is an AI-generated scene with a fictional instructor, not a customer's course.

  • Talking head, narrated slides and screen recordings all work. Only the speech is replaced.
  • Lip-sync is not part of the dub. It is an optional paid add-on for a finished dub of up to 5 minutes, priced per minute for the whole video, with the quote shown before it starts. It works best with a clearly visible face, so it suits a course trailer better than a long lecture.
  • Take care with recorded live Q&A, where people talk over each other, and with language lessons, where a dub would translate the words you are teaching.
SpanishOriginal

What is said: En esta clase aprendemos lo básico y mis alumnos de otros países la escuchan en su propio idioma.

What is said: In this class, we learn the basics, and my students from other countries listen to it in their own language.

What is said: Nesta aula aprendemos o básico e meus alunos de outros países a ouvem em seu próprio idioma.

Demo clip: an AI-generated scene with a fictional character. Dubbed with VDub v2, the model DubSync runs; lip-synced tracks use VSync v2.

Lip-sync shown in these examples is an optional paid add-on, separate from the dubbing trial.

Longest lesson
150 min
Split a longer recording first.
Largest file
1 GB
MP4, MOV or M4V. Files only, no links.
Target languages
28
The language you teach in is detected for you.

Each lesson is its own project, and each language is another one. Forty lessons in two languages make 80 projects, and input minutes are counted for every one. Add up your lecture minutes, multiply by the number of languages and compare the total with what a plan includes. See what each plan includes

The part that needs a person

Technical terms need a native check, because a dub can't be corrected by hand.

DubSync has no script editing and no glossary. You can't change a word before or after the dub, so accuracy depends on how the lesson was recorded and on who reviews the result.

  • Terms of art

    Most fields have one accepted translation for a term and several wrong ones. Some keep the English word. A general translation can miss either.

  • Code, commands and menu names

    What you read aloud is translated; what is on screen is not. A learner may hear a button named in Spanish and see it in English.

  • Numbers, units and formulas

    Doses, tolerances, prices and dates are the costly mistakes. Listen to every one of them.

  • Acronyms and proper names

    Say them slowly and the same way every time. A rushed acronym is easy to mishear.

Start small

Pilot one module before you dub the whole course.

  1. Pick the module with the hardest vocabulary

    If the densest lessons hold up in translation, the easier ones are a smaller risk. Choose one language: the one where you already have students or inquiries.

  2. Export each lesson as a file

    MP4, MOV or M4V, up to 150 minutes and 1 GB. Cut what you don't want dubbed: minutes are counted for the whole file.

  3. Dub the lessons one by one

    Upload a lesson, pick the language, check the minutes and the cost, confirm your rights and every speaker's consent, then start. You can close the page while it is processed. Download each MP4 when it is ready: exported videos are scheduled for deletion after 30 days.

  4. Have a subject expert watch every minute

    Send the dubbed MP4s with your term list and ask for timestamps of anything wrong. Re-record and dub again only the lessons that need it.

  5. Decide, then do the rest

    If the module holds up, dub the remaining lessons and translate the slides, worksheets, quizzes and sales page. If it doesn't, you have spent one module's minutes, not the whole course's.

Where the new edition will live

Marketplace rules for a second language edition.

Marketplaces set their own rules for a translated edition, and they are not alike. Rules change, so open the cited pages before you upload.

  • Udemy

    • One language per course
    • AI dubbing must be disclosed

    You choose one language for a Udemy course, and search and category filters list it with other courses taught in that language.4 So plan a Spanish edition as its own course, one that passes the usual minimums: at least 30 minutes of video in five or more lectures, a unique landing page, and audio in both channels that is synced to the video and not distracting.5

    Udemy accepts AI-made audio that meets its production standards and does not accept courses that are entirely AI-generated.3 AI translation, dubbing and voice cloning for multi-language versions are on its list of uses you must disclose, with a set sentence at the start of the course description.6

  • Skillshare

    • Dubbing not permitted
    • New classes in English only

    Skillshare's guidelines say dubbing is not permitted at this time. A new, standalone version of a class in another language is allowed, but lessons with a speaker on screen have to be re-recorded in that language, and demos or screencasts need a newly recorded voice-over. The same page says Skillshare is accepting new classes in English only for now.2 The passage still refers to a dubbing pilot planned for summer 2022, so it may be out of date: ask Skillshare for its current position.

  • Your own site or course platform

    • Your site, your decision
    • One MP4 per lesson

    On your own site the decision is yours. A hosted course platform has its own terms, which this page hasn't checked, so read them. Each dubbed lesson is a separate MP4: plan the edition as a copy of the course with new videos, translated lesson titles and translated downloads, and decide who answers students in the new language.

A warning from Udemy's instructor forum: in March 2025 an instructor wrote that after three English editions of their Spanish courses went through, the fourth was flagged for a copyright issue against their own original, and their account was disabled until support cleared it in under an hour.8 It is one person's account, not a policy, but a reason to contact instructor support before you submit a language edition.

Learners already meet AI dubs on large platforms: Coursera lists more than 100 AI-dubbed courses in Spanish, French, German or Portuguese and describes them as still spoken in the instructor's voice.9

Before you upload

Dub only lessons that are yours to dub.

  • You recorded the course and own it: go ahead. If an employer, a university or a publisher paid for the production, check who holds the rights first.
  • Guest lecturers, interviewees and co-instructors each have to agree, because a new voice is created from theirs.
  • Clips, music and slides licensed from someone else: check that the license covers a translated edition.
  • Someone else's course is not yours to dub, even if you paid for access to it.

Questions

Questions before you start

Can I translate a whole course in one upload?

No. Each lesson is its own project, and each language is another one. There is no batch upload, and you see the minutes and the cost before each dub starts.

How long can one lecture be?

Up to 150 minutes and 1 GB per file, as MP4, MOV or M4V. Split a longer recording in your editor first. DubSync takes files, not links, so for a lesson that only lives on a course platform you need the original file or a new export.

Can I fix a mistranslated term after the dub?

No. There is no script editing and no glossary. Re-record the sentence more plainly and dub that lesson again; the new dub is a new project and uses the lesson's minutes again. This is why the pilot module and the native review come first.

Will the dubbed lessons sound like me?

Each voice is created from the original speaker, so yours should sound similar, not identical. Clear speech recorded close to the microphone gives the best result.

Are my slides, quizzes and subtitles translated too?

No. A dub changes the audio only. Slide text, screen recordings, worksheets, quizzes and captions stay in the original language until you translate them yourself.

Can I sell the dubbed edition on a marketplace and on my own site?

That depends on each marketplace's terms, so read them first. Udemy, for example, says instructors keep the rights to their courses and may offer them on other services, but a course that is paid on Udemy can't be offered for free elsewhere.10 A course that Udemy has picked for a subscription collection carries an exclusivity rule: it covers competing on-demand content on other platforms and leaves out your own website.7

My lessons are public YouTube videos. Do I need DubSync?

Maybe not. YouTube's automatic dubbing is switched on by default for eligible creators and adds dubbed audio to the videos themselves, and you can choose to review dubs before they are published.11 DubSync is for when you need a file: a dubbed MP4 you can load into a course platform or your own site.

Plans from $4.90/month. You see the minutes and the cost before anything starts. See pricing

Sources

  1. Udemy Help. Instructors: Auto-Generated Subtitles Frequently Asked Questions. Accessed Oct 5, 2026.
  2. Skillshare Help Center. Language Accessibility Guidelines. Accessed Oct 5, 2026.
  3. Udemy Help. Course Quality Checklist: Use of AI. Accessed Oct 5, 2026.
  4. Udemy Help. Instructors: Select Your Course Language. Accessed Oct 5, 2026.
  5. Udemy Help. Udemy course quality checklist. Accessed Oct 5, 2026.
  6. Udemy Help. Course description: Rules and guidelines. Accessed Oct 5, 2026.
  7. Udemy Help. Instructors: Udemy subscriptions program frequently asked questions. Accessed Oct 5, 2026.
  8. Udemy Instructor Community. Does Udemy allow instructors to publish multiple versions of an existing course in other languages?. Published Mar 12, 2025; accessed Oct 5, 2026.
  9. Coursera. AI-dubbed courses | Learn in your language. Accessed Oct 5, 2026.
  10. Udemy Help. Teaching on Udemy: Frequently asked questions. Accessed Oct 5, 2026.
  11. YouTube Help. Use automatic dubbing (help article 15569972). Accessed Oct 5, 2026.

Keep exploring

Start with one lesson

Dub one lesson and hear your course in another language.

Upload it, see the minutes, then decide.

Upload a lesson

Only upload videos you have the rights to, with every speaker's permission.