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WebVTT (Web Video Text Tracks) is a W3C standard for displaying timed text in connection with the HTML5 <track> element. The early drafts of its specification were written by WHATWG in 2010, after discussions about what caption format should be supported by HTML5, the main options being the relatively mature, XML-based TTML or an entirely new but more lightweight standard based on the popular SRT format. The final decision was for the new standard, initially called WebSRT (Web Subtitle Resource Tracks).〔(【引用サイトリンク】title=WebVTT versus TTML: XML considered harmful for web captions? )〕 It shared the .srt file extension and was "broadly based on" (parts of) the SubRip format, though not fully compatible with it.〔(Understanding WebSRT format )〕〔(WebSRT ), from the WHATWG HTML draft specification, retrieved 2010-10-14〕The prospective format was later renamed WebVTT. In the (January 13, 2011 version of the HTML5 Draft Report ), the <track> tag was introduced and the specification was updated to document WebVTT cue text rendering rules. The WebVTT specification is still in draft stage but the basic features are already supported by all major browsers.== Main differences from .srt == * WebVTT's first line starts with ''WEBVTT'' after the optional UTF-8 byte order mark * there is space for optional header data between the first line and the first cue * Timecode fractional values are separated by a full stop instead of a comma * Timecode hours are optional * The frame numbering/identification preceding the timecode is optional * Metadata frames identified by the word ''NOTE'' can be added * Only supports extended characters as UTF-8 * CSS in a separate file defined in the companion HTML document for C tags is used instead of the FONT tag * Cue settings allow the customization of cue positioning on the video〔(【引用サイトリンク】url=http://dev.w3.org/html5/webvtt/#webvtt-cue-settings )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「WebVTT」の詳細全文を読む スポンサード リンク
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