This document is subject to change without notice.

This is a guide for authoring files in the Web Video Text Tracks (WebVTT) file format. It is an informative specification of WebVTT - the normative specification is the [[WEBVTT]] specification. While the [[WEBVTT]] specification is targeted at User Agent developers, this document targets Web Developers and other WebVTT authors.

Introduction

WebVTT (Web Video Text Tracks) is a file format conceived to specify caption, subtitle and similar text files that render blocks of text in synchronization with a video file. Such files are also called "text tracks".

WebVTT is a line-based text format. This is an example WebVTT file:

WEBVTT

0:00:15.000 --> 0:00:17.951
At the left we can see...

0:00:18.166 --> 0:00:20.083
At the right we can see the...

0:00:20.119 --> 0:00:21.962
...the head-snarlers

0:00:21.999 --> 0:00:24.368
Everything is safe.
Perfectly safe.

0:00:24.582 --> 0:00:27.000
Emo?
Emo!

0:00:28.206 --> 0:00:29.996
Watch out!
      

On the Web, we use the <video>, <audio> and <track> tags in [[HTML5]] to connect a text track file with a media file. This is an example markup which provides a captions file that is active by default:

<video src="elephants_dream.webm" controls>
  <track src="elephants.vtt" kind="captions" srclang="en-US" default>
</video>
      

This is how the first cue in the above example will be rendered:

first cue rendered on top of Elephants Dream video

WebVTT File Structure

WebVTT File Kinds

Default Styling

WebVTT Cue Markup

WebVTT Cue Settings

WebVTT Cue Styling

Acknowledgements