The Dotsub Dictionary: All the video localization terms you should know

December 5, 2022

When you first start localizing your audiovisual content, you’ve undoubtedly got a lot of questions: What’s the difference between a closed caption and a subtitle? And what do all these file extensions mean?

We get it. And at Dotsub, we’ve worked hard to make video localization easy for you and your company. In that spirit, we’ve collected the most important terms you’ll need to know when adding captions and working with our program. They’re broken down into three key categories: Video Localization Services, Specifications and File Formats.

Getting familiar with these terms will give you a better idea of what your company really needs when it comes to video localization. That’s a huge step in starting the process and deciding how to move forward. And if something doesn’t make sense, no worries. At Dotsub, we’re prepared to help your company find the best solution for your video localization needs and answer any questions you may have along the way.

Video localization services


This is text displayed in the same language of the spoken dialogue, time-coded to match the visual content of the video. You might also see them called “narrative” or “broadcast-style” captions.


As opposed to captions, subtitles are text displayed in a language different from the one being spoken on video. When you request a subtitling service, the video language —known as the “source language”— will be translated into an alternative language of your choice called “target language.”

Closed captions

This type of captions transcribe all the audio in your video—from dialogue to sound effects to music cues and beyond.

They’re time-coded to match the visuals on screen and give your audience a fuller experience. The main characteristic is that the viewer can even toggle them on or off to choose how they want to watch the video. You’ve probably seen something like this on YouTube or Netflix’s captioning functionalities.

Open captions

Like closed captions, open captions serve the same goal in terms of accessibility—with one key difference. Instead of toggling them on or off, they’re embedded in the video itself and are mostly seen on platforms that don’t have true closed captioning functionality. That’s why you might see them called “burnt-in” captions.

These are fantastic for social media content like TikTok or Instagram Reels that don’t have Closed Caption capabilities. So, adding your own open captions is a savvy way to reach a larger audience.

Voice Over

This is a dialogue track recorded over a video, usually to add narration to a story or explain some information. You’ve heard this audio in documentaries, digital learning modules or news segments. The person speaking is typically never seen and can be a real person or digitally-created voice.


You might decide to replace the original audio performance with a recording in a new language. This process is known as dubbing.

The new audio is designed to perfectly sync with the performance on screen. That sometimes involves rewriting the script to match the actor’s lip movement. And it requires the voice actor to deliver a true performance. They’ll recreate the tone, emotions and nuance of what’s on screen—including a full range of expressions, from laughter to tears.



Time codes

These mark specific points of time in a video clip, down to the millisecond or even an assigned frame in the video. You’ll see them written in the format hours:minutes:seconds:frames (e.g. 00:14:56:10).

Subtitles and captions are synced to both the audio and footage by referencing the start and end time-codes.

Line breaks

Since the length of the lines is constrained by the size of the screen, often a sentence doesn’t fit in one line. The point where a line of text ends is known as a line break.

These should be broken at logical points, ideally at a piece of punctuation like a period, comma or dash. Above all, separating parts of speech such as an article and a noun (e.g. the + bus, a + taxi) should be avoided.

On-screen text

All the video’s written text that isn’t a caption or subtitle is known as on-screen text. That includes title cards, graphics or any information embedded in the video.

Character limit

Depending on in-country accessibility standards, medium or language, there’s a maximum number of characters you can include in a line, known as the character limit. It’s a good idea to be mindful of this number and how different letters, spaces, punctuation marks and symbols affect your limit.

Speaker identification

To identify who’s talking, you’ll want to lean on accessibility best practices for speaker identification. Common methods include using their name, numbering (Speaker 1,2) or gender before their spoken dialogue appears in a caption.

Dialogue style

When multiple people are talking, you’ll want to mark the start of each of their lines. Hyphens and double chevrons are the two most common dialogue styles used in captions to show that a new person is speaking.

File formats


SubRip (.srt)

This is the most popular format, supported in most of the basic media players. Typically, when using .srt, you won’t be able to choose the position of your captions or include special characters or symbols.

WebVTT (.vtt)

This format adds captions to HTML5 pages, so it’s supported in most video platforms. And you have the flexibility to include positioning specifications, special characters and text formatting.

Timed text Markup Language

Developed by the World Wide Web Consortium (W3C), this is the standard for XML captions and designed to incorporate all functionality of existing formats.

Have any more questions about video localization? Or just want to learn more about how we help companies reach global audiences? Reach out to our team at [email protected].

Want to learn more? Contact Dotsub today at [email protected].

We’re committed to your privacy. Dotsub uses the information you provide to contact you about our relevant content and services. You may unsubscribe at any time. For more information, check out our privacy policy.

Share This