Translation in FAB Subtitler

FAB Subtitler supports translating a complete subtitle file from one language to another language. External translation services are used. Currently the following translation services are supported:

To use an online translation service you will need to create an online account and obtain the API Key that you will use for translating and enter the API Key in FAB Subtitler Options.

The translation functionality:

  • Translates the complete subtitle file.
  • Instead of translating every subtitle, complete phrases of the original subtitle file are translated.
  • Translated phrases are distributed to subtitles so that the IN timecode of every phrase is preserved, but every phrase is distributed to subtitles following special rules and the duration for every subtitles is calculated according to the amount of text in every translated subtitle.
  • Therefore translated subtitles will not have exactly the same timecodes as in the original subtitle file, but the beginning of every phrase will still have the same IN timecode.

Configuration

To be able to use the translation functionality it is necessary to configure one or multiple translation services that will be used. This is done in Options / Special / Translate:

Translating a subtitle file

To translate a subtitle file from one language to another language:

  • In the ribbon click on Extras / Translate.
  • In the translation window select the translation service and the target language.
  • Click on the “Translate” button which will translate the subtitle file and open a new subtitle file with translated subtitles.

The translation of hundreds of subtitles will only take a few seconds.

Installing LibreTranslate under Windows

The following describes how to install LibreTranslate as a Windows Computer so that it can be used locally without an internet connection.

  • For Windows 11: Install Docker:

    • Open Command Prompt as Administrator
    • Run: wsl --update
    • Run: winget install Docker.DockerDesktop
    • Reboot computer
    • Open Docker Desktop
    • Go to Settings → General
    • Check “Start Docker Desktop when you sign in to your computer”
    • Open Command Prompt
    • Run: docker --version
    • Run: docker run hello-world
    • Note that Docker Desktop requires that the user is logged-in to start LibreTranslate.

  • For Windows Server:

    • Open PowerShell as Administrator
    • Run: Install-Module -Name DockerMsftProvider -Repository PSGallery -Force
    • Run: Install-Package -Name docker -ProviderName DockerMsftProvider -Force
    • Restart-Computer

  • Install LibreTranslate:

    • Open Command Prompt
    • Run: docker run -d -p 5000:5000 --restart unless-stopped --name libretranslate libretranslate/libretranslate --load-only en,es,fr,de,it (specify required languages)
    • Check if LibreTranslate is running: docker ps
    • Display LibreTranslate logs: docker logs libretranslate -f (Stop with Ctrl+C))
    • LibreTranslate will take some minutes to start for the first time because it has to download translation models from the internet
    • 5 minutes after first start test if LibreTranslate is running: curl http://localhost:5000/translate -X POST -H "Content-Type: application/json" -d "{\"q\":\"Hello\",\"source\":\"en\",\"target\":\"es\"}"

This page was last updated on 2025-12-02