Transcription teams are used to working with audio and text, but once a client asks for subtitles in several languages, the job changes. Timing, line length and file formats suddenly matter as much as the words. A caption file that looks like a simple text document is in fact a precise structure of cues, timestamps and settings, and a single misplaced character can make a video player reject it. A CAT tool helps teams translate the text while keeping that structure safe.
What is inside a caption file
The two formats you meet most often are SRT and WebVTT. Both consist of cues, which are short pieces of text with a start and end time. SRT is the older and simpler format, while WebVTT is the standard used by web video players and learning platforms. It adds a header, optional cue identifiers and settings for position and style. The text itself is only a small part of the file, and everything around it must stay untouched.
Why plain text editors cause trouble
Many teams start by opening caption files in a text editor and typing the translation over the original. This works for a few lines and fails at scale. Timestamps get deleted by accident, a comma replaces a period, speaker tags disappear, and nobody notices until the video is published. There is also no memory of previous work, so identical phrases are translated again and again, which wastes time on repetitive material such as greetings and standard disclaimers.
How a CAT tool protects the structure
A modern CAT tool reads the caption file, hides the technical parts and shows only the text that needs translation. Each cue becomes a segment, and the timing stays locked in the background. Translators work in a clean editor, see the original next to their version, and get warnings when something looks wrong. When the work is finished, the tool writes the file back in the right format, with timestamps intact.
Learning the WebVTT format
Because WebVTT is used so widely on the web, it is worth understanding its rules. A short explanation of WebVTT files shows how headers, cues and settings fit together and what must never be changed during translation. Teams that know these rules can brief translators properly and avoid the most common mistakes.
Reading speed and line length
Subtitles are not translated like ordinary paragraphs. Viewers must be able to read them in the time they are on screen, so sentences often have to be shortened. Many teams aim for around fifteen to seventeen characters per second and no more than two lines per cue. A good editor shows the character count and warns when a cue is too long, so translators can adjust the wording while they work, not after the file has been exported.
Reusing repeated lines
Transcription projects often contain repeated material: welcome messages, speaker introductions, legal notices, calls to action. A translation memory stores approved translations of these lines and offers them again. For a series of videos with the same format, the savings are noticeable, and the style of the subtitles becomes more consistent across episodes, which viewers appreciate even if they do not notice why.
Names, terms and speaker labels
Names of people, products and places must be spelled the same way throughout a series. A glossary keeps these decisions in one place. Speaker labels and sound descriptions, such as music or laughter, follow conventions that differ between languages, so a short style guide for each language prevents guesswork. When several translators share a project, the glossary and guide are what keep the result coherent.
Standards and specifications
The WebVTT format is defined in a public specification maintained by the W3C, and it is a useful reference when a player behaves unexpectedly. You can read the full WebVTT specification to see exactly how cues, settings and comments are meant to work. Most teams will not need to read it all, but it settles arguments quickly when a client asks why a file was rejected.
Quality checks before delivery
Before delivering subtitles, run automatic checks for missing tags, overlapping times, empty cues and cues that exceed the reading speed limit. Then watch the video with the translated subtitles at least once. Timing problems, awkward line breaks and meaning errors are far easier to spot while the video plays than when reading a list of lines.
Delivering in the right format
Different platforms want different files. A learning platform may need WebVTT, a social network may prefer SRT and a broadcaster may ask for another format altogether. Keep the translated text in one project and export to each format at the end, using clear file names that include the language code. This approach avoids translating the same text three times for three destinations.
Final thoughts
Subtitles are a small file with a big responsibility. Putting caption translation inside a CAT tool protects the technical structure, speeds up repeated work and gives reviewers a clear view of what changed. For transcription teams moving into multilingual work, it is one of the most practical upgrades available.