What is a VTT file and how do I make one?

A VTT file is a WebVTT subtitle file: a plain text format for captions on the web, holding each line of dialogue with the times it appears and disappears. You can make one for free with Video by Zaweba by creating captions from your film's speech on your own PC and exporting them as WebVTT from the Captions tab. The app reads VTT files too, so you can bring existing captions in and fix them.

Because the file is only text, it's small, easy to check and easy to edit. It sits beside the video rather than inside it, and the player shows the words over the picture when someone turns captions on.

Inside a WebVTT file

Open a .vtt file in a text editor and you'll see a short header line, then a series of cues. Each cue is a start time, an end time and the words to show between them. That's essentially it. Web video players understand the format directly, which is why it's common on websites, online courses and video hosting services that accept a caption file alongside the upload.

It's a close cousin of SubRip (.srt), the other everyday caption format. The two carry the same basic information with slightly different layout. Some places ask for one and some for the other, and it costs nothing to export both.

Making the captions in Video by Zaweba

Edit your film first, or at least lock the timing of the speech, since captions follow the cut. Then use the Captions tab to make captions from the speech. Recognition runs on your PC with whisper.cpp, voice line by voice line, and no audio is sent anywhere. Each cue is kept to at most two short lines so it reads comfortably.

If you have a script, the app lines up the script's words with what it heard. The timing comes from the speech and the spelling comes from your script, so names and technical terms come out as you wrote them.

Play the film through with captions showing and correct anything odd. Spelling is marked in captions, and Edit > Find and replace works across them, so a misheard name can be fixed everywhere in one go.

Exporting the .vtt

From the Captions tab, export the open caption track as WebVTT. Upload that file next to your video wherever the platform asks for subtitles or captions. If a timeline has several caption tracks, for example the original language and a translation, each can be exported on its own, so you end up with one .vtt per language.

Already have a VTT from somewhere else? Import it in the same place. That's useful when someone has sent you captions to check, or when you want to burn an existing set into the picture for a social clip where most people watch without sound.

When another format suits better

VTT is right for the web. A broadcaster or a professional subtitling house may want something else, and Video by Zaweba also imports and exports Scenarist SCC, TTML and IMSC1, DFXP, EBU STL and MacCaption MCC alongside SubRip. Ask the person receiving the file which one they need, then export that.

And if the video is going somewhere that doesn't take caption files at all, burn the captions into the picture instead. You lose the option to switch them off, but every viewer sees them.