WebVTT captions
The W3C caption standard for HTML5 video. More expressive than SRT and used by YouTube's web player under the hood.
WebVTT is the W3C caption standard, headed by `WEBVTT` and supporting cue styling and positioning. YouTube uses WebVTT to ship captions to the browser. SumTube parses WebVTT or json3 and extracts the same segment structure either way.