TTML (Timed Text Markup Language, formerly specified as DXFP) was published as a detailed standard in November 2010 by the World Wide Web Consortium (W3C) that covers timed text on the Web with the goal being to define a nonproprietary, standardized format that could be used for displaying text synchronized with other elements such as audio and video. Timed text refers to the presentation of text media in conjunction with other media, such as audio and video. Typical applications of timed text are the real-time subtitling of foreign-language movies on the Web, closed captioning for people lacking audio devices or having hearing issues, karaoke, scrolling news items or teleprompter applications.
Similar to other professional sectors with a highly automated production process, the broadcast industry depends on reliable and stable standards to guarantee the quality of their services. The benefit of a formal standard that uses XML (Extensible Markup Language) as an established technology in this context is driven by the large increase of video content distribution over IP-based networks. The demand for subtitles to show with video is rising as well. In some regions provisioning of subtitles with online content is also an obligation from the regulator.
Incompatible, nonstandardized formats for captioning, subtitling and other forms of timed text are frequently found on the Web. Often this means that when creating a Synchronized Multimedia Integration Language (SMIL) presentation, the text portion often needs to be targeted to a particular playback environment. In addition, the accessibility community relies heavily on captioning to make audiovisual content accessible. The lack of an interoperable format adds significant additional costs to the costs of captioning Web content. Also, for professional content providers including broadcasting stations, a standardized format such as TTML gives broadcast stations the means to guarantee the quality of their online services and to satisfy the expectations of their audience.
Standardization committees from the broadcast and movie domain have adopted and promoted TTML as their format for subtitles. The Society of Motion Picture & Television Engineers (SMPTE) extended TTML to SMPTE-TT, the Digital Entertainment Content Ecosystem consortium (DECE) defined a TTML profile for the common file format (CFF-TT), and the European Broadcasting Union (EBU) published the TTML subset EBU-TT] for the interchange, archiving and production of subtitles.
TTML was adopted as an XML standard by the EBU due to the fact that it has well-documented Unicode support, which was missing in the prior binary EBU STL format. While the translation process of spoken text into subtitles requires a large amount of manual work in regard to transcription and formatting, the deployment of subtitles in different subtitle formats for linear and non-linear TV is only practically feasible when it is automated.