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CADET - Caption and Description Editing Tool

Read the CADET download and installation instructions now!

The National Center for Accessible Media at WGBH (NCAM) has developed CADET (Caption and Description Editing Tool), partially funded by a grant from the Massachusetts Attorney General's Office.

CADET is free, downloadable caption-authoring software that enables anyone to produce high-quality caption files that are compatible with any media player that supports the display of captions. CADET can also be used to generate audio-description scripts. CADET does not require an internet connection in order to operate: it runs locally in any Web browser, so users do not need to upload private videos or proprietary content to servers or video-hosting sites in order to create captions.

Until now there has been no straightforward, inexpensive offline caption-editing software for creating post-production online captions or audio-description scripts. Although automated speech-to-text captioning is widely available for user-generated and professionally produced online videos, its high frequency of spelling errors and missing punctuation, and even occasional obscenities, does not provide reliable access for any users. Unfortunately, many videos remain inaccessible as a result of missing or poor-quality captions.

CADET implements all of the basic features necessary to creating high-quality captions, plus many of the functions available only in high-end caption-authoring workstations. CADET allows users to...

  • create captions for video formats that play natively in browsers (e.g., mp4, m4v);
  • import plain-text transcripts for editing and timing;
  • transcribe caption text directly into the caption editor;
  • edit, style and time captions;
  • import existing caption files (WebVTT, SRT, TTML, QTText, SCC, Plain Text) for clean-up, editing or re-timing;
  • export caption files in common formats, including WebVTT, SRT, TTML, QTText, SAMI, SCC, and plain-text scripts.

CADET builds on the success of MAGpie (originally released in 2000), the first do-it-yourself captioning application to be made available on the internet. Both CADET and MAGpie were created by staff at WGBH, where broadcast captioning was invented in 1971. Unlike other captioning applications, CADET was created by developers with unique knowledge gained from 45 years of research and development into caption technology.

The following software is required to use CADET:

  • Any OS which supports Node.js: e.g., Microsoft Windows (32-/64-bit versions e.g. Win7, Win8, Win10, etc.) or Macintosh OS X
  • Node.js
  • A modern Web browser (i.e., one that supports HTML5, such as Internet Explorer, Edge, Firefox, Chrome or Safari)

Download CADET now, then follow the installation instructions for your operating system.

CADET help

You can get help with CADET in the following ways:

  • Read the help documentation that will walk you through the basics of captioning with CADET.
  • Join the CADET user group, the primary means of communication between users and the CADET development team. This is where you can go to get help from other CADET users, as well as report problems and request new features.
  • Head over to the CADET Tutorials for examples and tips on how to use CADET's many features. We show you how to install CADET, create captions, and much more.