View source for Timed text

{{short description|Presentation of text media in synchrony with other media, such as audio and video}}
{{For|the Wikipedia guideline on timed text|Wikipedia:Manual of Style/Accessibility#Video}}
{{refimprove|date=December 2011|Tapan das=Tapan das}}
'''Timed text''' is the presentation of text media in synchrony with other media, such as audio and video.

==Applications==
Typical applications of timed text are the real-time [[subtitles|subtitling]] of foreign-language movies on the [[World Wide Web|Web]], [[captioning]] for people lacking audio devices or having [[hearing impairment]]s, [[karaoke]], scrolling news items or [[teleprompter]] applications.

Timed text for [[MPEG-4]] movies and cellphone media is specified in [[MPEG-4 Part 17|MPEG-4 Part 17 Timed Text]], and its [[MIME]] type is specified by RFC 3839.

==Markup language specifications==
The [[W3C]] keeps two standards intended to regulate timed text on the [[Internet]]: the [[Timed Text Markup Language|Timed Text Markup Language (TTML)]]<ref>Glenn Adams (Ed.): [http://www.w3.org/TR/ttaf1-dfxp/ Timed Text Markup Language (TTML) 1.0 - W3C Recommendation, 18 November 2010]</ref> and [[WebVTT]].<ref>{{Cite web |url=https://www.w3.org/TR/webvtt/ |title=WebVTT: The Web Video Text Tracks Format|access-date=2023-12-20}}</ref>
[[SMPTE]] created additional metadata structures for use in TTML and developed a profile of TTML called [[SMPTE-TT]].<ref>{{citation |url=http://store.smpte.org/product-p/st%202052-1-2010.htm
 |format=PDF |title=ST-2052-1; SMPTE Timed Text, Copyright © 2010 SMPTE. August 2010 |author=SMPTE |date=August 2010 |access-date=2011-03-25}}</ref> The [[DECE]] incorporated the SMPTE Timed Text in their [[UltraViolet (System)|UltraViolet]] [[List of file formats|Common File Format]] specification.

==Competing formats==
Interoperability for timed text came up during the development of the [[Synchronized Multimedia Integration Language|SMIL]] 2.0 specification. Today, incompatible formats for captioning, subtitling and other forms of timed text are used on the Web. This means that when creating a SMIL presentation, the text portion often needs to be targeted to a particular playback environment. Moreover, the accessibility community relies heavily on captioning to make audiovisual content accessible. The lack of an interoperable format adds a significant additional cost to the costs of captioning Web content, which are already high.

==Example==
The following is an extract from the [[commons:TimedText:Krazy Kat Bugolist 1916 silent.ogv.en.srt|English closed captioning file]], in [[SubRip]] format, for the 1916 [[:File:Krazy Kat Bugolist 1916 silent.ogv|Krazy Kat Bugolist film]].

 1
 00:00:22,000 --> 00:00:27,000
 I'll teach thee Bugology, Ignatzes
 
 2 
 00:00:40,000 --> 00:00:43,000 
 Something tells me
 
 3 
 00:00:58,000 --> 00:01:59,000 
 Look, Ignatz, a sleeping bee

The equivalent in W3C [[WebVTT]] is the following:

 WEBVTT
 
 00:22.000 --> 00:27.000
 I'll teach thee Bugology, Ignatzes
 
 00:40.000 --> 00:43.000 
 Something tells me
 
 00:58.000 --> 01:59.000 
 Look, Ignatz, a sleeping bee

The equivalent in W3C [[Timed Text Markup Language|TTML]] is the following:

<syntaxhighlight lang="xml">
<tt xmlns="http://www.w3.org/ns/ttml">
  <body>
    <div begin="22s" dur="5s">
      <p>I'll teach thee Bugology, Ignatzes</p>
    </div>
    <div begin="40s" dur="3s">
      <p>Something tells me</p>
    </div>
    <div begin="58s" dur="61s">
      <p>Look, Ignatz, a sleeping bee</p>
    </div>
  </body>
</tt>
</syntaxhighlight>

== See also ==
* [[Text over IP]]
* [[Subtitle (captioning)]]

== References ==
<references />

== External links ==
{{Commons|Commons:Timed Text}}
* [http://www.w3.org/AudioVideo/TT/ The W3C timed text homepage]
* [[W3C]]'s [http://www.w3.org/2008/WebVideo/Activity.html Video in the Web Activity Statement]
* Also see [[DAISY Digital Talking Book|DAISY Digital Talking Book standard]]

{{W3C Standards}}

[[Category:Subtitle file formats]]
[[Category:Subtitling]]
[[Category:Text codecs|Timed text]]
[[Category:User interface techniques]]
[[Category:World Wide Web Consortium standards]]