An SBV file is a plain-text caption file in the SubViewer format. YouTube lists it on its help page of supported caption files as "SubViewer (.sbv or .sub)", next to SubRip (.srt). Each caption in the file is a timing line, then the words, then a blank line. There are no cue numbers and no styling.
Most people find an .sbv file after downloading captions from YouTube Studio. You can open it in any text editor, edit the words, and upload it back to YouTube. If another app or player wants SRT instead, the change is small: the timestamps are written differently and SRT adds numbers. This guide shows the exact syntax, how SBV differs from SRT and VTT, and how to open, fix and convert one.
What an SBV file looks like
Here are the first two captions of a short SBV file, line by line:
| Line in the file | What it means |
|---|---|
| 0:00:01.200,0:00:03.800 | Start time, a comma, then end time |
| Welcome back to the channel | First line of caption text |
| Today we are fixing caption files | Optional second line of the same caption |
| (blank line) | Ends the caption |
| 0:00:04.100,0:00:06.500 | Timing of the next caption |
| Let's start with the format | Text of the next caption |
That is the whole format. YouTube's own example uses the same pattern, with timings such as 0:00:00.599,0:00:04.160 and no numbers above the captions (YouTube Help, read 21 October 2026).
The rules of the SBV format
- Timing line first. Each caption opens with the start time and the end time on one line, separated by a comma with no spaces.
- Hours, minutes, seconds, milliseconds. Times are written as H:MM:SS.mmm. Hours usually take one digit, and a full stop sits before the milliseconds.
- Text below the timing. One or two short lines read best. Each new line in the file is a new line on screen.
- A blank line between captions. This is how the reader knows one caption has ended.
- No cue numbers. Unlike SRT, nothing counts the captions.
- No styling. YouTube says only basic versions of SRT and SBV are supported and "No style info (markup) is recognized."
- Plain UTF-8 text. The same YouTube page says the file "must be in plain UTF-8."
Some older SubViewer files look slightly different. The VideoLAN wiki describes two versions. SubViewer 2 files can start with an [INFORMATION] header holding a title and author, and they write each caption on one line with [br] marking the line breaks. If your file has [br] in the text, it is that older style. The caption content is the same.
One warning about the .sub extension. YouTube treats .sub as SubViewer too, but other subtitle formats also use .sub. If a .sub file will not load, open it in a text editor and look at the first lines. If they look like the table above, it is SubViewer.
SBV vs SRT vs VTT
The three formats carry the same information: when each caption starts, when it ends, and what it says. They differ in punctuation and in how much extra they allow.
| Feature | SBV (SubViewer) | SRT (SubRip) | VTT (WebVTT) |
|---|---|---|---|
| Cue numbers | None | Required, counting from 1 | Optional cue identifiers |
| Timing line | 0:00:01.200,0:00:03.800 | 00:00:01,200 --> 00:00:03,800 | 00:00:01.200 --> 00:00:03.800 |
| Separator between times | Comma | Arrow | Arrow |
| Before milliseconds | Full stop | Comma | Full stop |
| First line of the file | First timing line | 1 | WEBVTT |
| Styling and position | None on YouTube | None on YouTube | Position, bold, italic, underline on YouTube |
| Where it is used | Mostly YouTube | Almost every player, editor and platform | Web players and browsers |
Sources: YouTube Help "Supported subtitle and closed caption files" and the W3C WebVTT draft of 20 May 2026, both read 21 October 2026.
The practical difference is reach. SRT is the format other apps expect. Video editors, social platforms and desktop players are far more likely to accept an SRT than an SBV. VTT is the format browsers use for the HTML5 video track element. SBV is mainly useful when you are moving captions in and out of YouTube.
Where you get an SBV file
YouTube's help page on editing captions gives the download path:
- Sign in to YouTube Studio.
- Select Subtitles in the left menu.
- Click the video.
- Click Edit next to the language you want.
- Click Options, then Download subtitles.
YouTube Help does not list which file types the download offers. A university IT guide from the FASE Education Technology Office (last updated 6 January 2023, read 21 October 2026) lists .vtt, .srt and .sbv. If you are offered a choice, pick the format your next app needs, and you may not need to convert at all.
You can only use this path for videos on a channel you manage. For anyone else's video, see how to download subtitles from YouTube.
How to open and edit an SBV file
An SBV file is plain text, so you do not need special software.
- Windows: right-click the file, choose Open with, then Notepad.
- Mac: open it with TextEdit, or any code editor. YouTube's help page names TextEdit and Notepad for this job.
- Phone: any plain-text or code editor app can open it. Office apps that open it as a formatted document are not a good fit.
When you edit, change only the text lines. Leave each timing line exactly as it is, unless you are deliberately moving a caption. Keep the blank line between captions. When you save, keep it as plain text in UTF-8 and keep the .sbv extension. A rich-text format, or a second extension such as .sbv.txt, is a common reason a re-upload fails.
To upload it again, go to Subtitles in YouTube Studio, choose Upload file, then pick With timing, because an SBV already contains its timings. Then select the file and save (YouTube Help, read 21 October 2026).
If you see odd symbols where accented letters, ₹ signs or non-Latin scripts should be, the file was probably saved in another encoding. Paste the text into the free subtitle encoding checker to look for damaged characters, a byte order mark and line-ending problems, then save it again as UTF-8.
How to convert an SBV file to SRT
The quickest way is the free SBV to SRT converter. It runs in your browser, so the file is not uploaded anywhere.
- Open the converter and paste the contents of your .sbv file, or open the file.
- The tool reads each timing line, turns [br] into a real line break, and numbers the captions from 1.
- Check the preview, then download the .srt file.
If you would rather do it by hand, the change is mechanical:
- Add a number above each caption, starting at 1.
- Replace the comma between the two times with a space, an arrow and a space ( --> ).
- Change the full stop before the milliseconds to a comma.
- Write hours with two digits, so 0:00:01.200 becomes 00:00:01,200.
- Keep one blank line between captions and save as UTF-8 with the .srt extension.
Need VTT instead? Convert to SRT first, then use the SRT to VTT converter. Want to change a few words or timings after converting? The SRT editor lets you edit each caption's text and times in the browser and download the result.
Common SBV problems and fixes
- YouTube rejects the upload. Check that the file is plain UTF-8 and that you chose With timing. Also check that every timing line has both times and a comma between them.
- Captions appear but are all shifted. If every caption is early or late by the same amount, the video was probably trimmed after the captions were made. Shift all the times at once rather than editing each line.
- Two captions merge into one. A blank line is missing between them.
- Brackets or tags show on screen. YouTube ignores styling in SBV, so any tags you add show up as text. Remove them.
- Another app will not open it. Many players and editors do not read SBV. Convert it to SRT.
For a broader comparison of caption file types and where each one is accepted, see SRT vs VTT vs burned-in captions.
Can CapsAI make an SBV file?
No. CapsAI does not create, import or export SBV, SRT or VTT files. It makes captions from the speech in a video, in 11 spoken languages, and burns them into the picture, so you download one MP4 with the captions already on it. The converters and checkers on capsai.co/tools are separate free tools for caption files you already have.
That difference matters for where the video is going. An SBV or SRT file is a separate track that a platform shows as closed captions, and viewers can turn it off. Burned-in captions are part of the video, so they show wherever the file is posted, including apps that have no way to upload a caption file.
What to do next
If you have an SBV from YouTube and need it somewhere else, convert it with the SBV to SRT converter and check the encoding before you upload. If you are fixing the captions to post them back on YouTube, edit the text lines in a plain-text editor, keep the timings, and re-upload with timing.
If what you actually want is captions drawn onto a short video, you can skip caption files completely. CapsAI takes an MP4 or MOV up to 10 minutes long and gives back an MP4 with styled captions burned in. Every new account gets 3 free minutes to start, and one-time packs start from $4 (₹49 in India, €4 in the euro area).
