WebVTT

This specification defines WebVTT, the Web Video Text Tracks format. Its main use is for marking up external text track resources in connection with the HTML element. WebVTT files provide captions or subtitles for video content, and also text video descriptions [[MAUR]]( "Media Accessibility User Requirements") , chapters for content navigation, and more generally any form of metadata that is time-aligned with audio or video content. This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C standards and drafts index . This document was published by the W3C Timed Text Working Group as a Candidate Recommendation Draft using the Recommendation track . This document is intended to become a W3C Recommendation. For this specification to exit the CR stage, each normative feature is expected to meet the requirements set out in the charter of the Timed Text Working Group to demonstrate adequate implementation experience , and need to be documented in the implementation report. The Working Group does not require that implementations are publicly available but encourages them to be so. This document was produced by a group operating under the W3C Patent Policy . W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent that the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy . A cumulative summary of all changes applied to this version since the WebVTT First Public Working Draft was published is available at Changes from FPWD WebVTT . The WebVTT (Web Video Text Tracks) format is intended for marking up external text track resources in connection with the HTML element. WebVTT files provide captions or subtitles for video content, and also text video descriptions [[MAUR]]( "Media Accessibility User Requirements") , chapters for content navigation, and more generally any form of metadata that is time-aligned with audio or video content. The majority of the current version of this specification is dedicated to describing how to use WebVTT files for captioning or subtitling. There is minimal information about chapters and time-aligned metadata and nothing about video descriptions at this stage. The main use for WebVTT files is captioning or subtitling video content. Here is a sample file that captions an interview: You can see that a WebVTT file in general consists of a sequence of text segments associated with a time-interval, called a cue (definition ). Beyond captioning and subtitling, WebVTT can be used for time-aligned metadata, typically in use for delivering name-value pairs in cues. WebVTT can also be used for delivering chapters, which helps with contextual navigation around an audio/video file. Finally, WebVTT can be used for the delivery of text video descriptions, which is text that describes the visual content of time-intervals and can be synthesized to speech to help vision-impaired users understand context. This version of WebVTT focuses on solving the captioning and subtitling use cases. More specification work is possible for the other use cases. A decision on what type of use case a WebVTT file is being used for is made by the software that is using the file. For example, if in use with a HTML file through a element, the kind attribute defines how the WebVTT file is to be interpreted. The following subsections provide an overview of some of the key features of the WebVTT file format, particularly when in use for captioning and subtitling. Line breaks in cues are honored. User agents will also insert extra line breaks if necessary to fit the cue in the cue’s width. In general, therefore, authors are encouraged to write cues all on one lin