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Created: January 23, 2003.
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W3C Charters Timed-Text Working Group (TTWG).

W3C has announced the creation of a new Timed Text Working Group (TTWG) as part of the Synchronized Multimedia Activity (SYMM). The mission of the Timed Text Working Group is to develop an XML based format used for the representation of streamable text synchronized with some other timed media, like audio and video. Working Group members envision that the Timed Text specification will cover "all necessary aspects of timed text on the Web. Typical applications of timed text are the real time subtitling of foreign-language movies on the Web, captioning for people lacking audio devices or having hearing impairments, karaoke, scrolling news items, or teleprompter applications. On the Web, there is no standard method for displaying text which is synchronized with other elements, such as video and audio. The three most popular multimedia players -- Apple's QuickTime Player, Microsoft's Windows Media Player and RealNetworks' RealPlayer -- support only their own proprietary text formats (QText, SAMI and RealText, respectively). As a result, multimedia authors must write synchronized text files in multiple formats if they wish to support more than one player. A standardized timed-text format would eliminate this duplication of work. It would also simplify the creation and distribution of synchronized text for use with a multitude of devices, both software and hardware, such as multimedia players, caption encoders and decoders (EIA-608, 708 and TeleText, for example), character generators, LED displays and other text-display devices."

Timed-Text Working Group description

From the Charter and TTWG Page:

The issue of developing an interoperable timed text format came up during the development of the SMIL 2.0 specification. Today, there are a number of incompatible formats for captioning, subtitling and other forms of timed text used on the Web. This means that when creating a SMIL presentation, the text portion often needs to be targetted to one particular playback environment. This poses an issue for creating interoperable SMIL presentations. Moreover, the accessibility community relies heavily on captioning to make audiovisual content accessible to a hearing-impaired audience. The lack of an interoperable format adds a significant additional cost to the costs of captioning Web content, which are already high.

Timed Text will enrich the user experience for services involving timed text, and is seen as an important stimulus for instance in the usage of captioning and subtitling. The organizations willing to work on Timed Text include vendors of streaming multimedia technology, web browser companies and representatives of the accessibility community.

Coordination with External Groups: Outside W3C, a number of groups are working technologies relevant for the Timed Text WG.

  • 3GPP has developed a binary timed text format for the MMS service (TS 26.234 Section 7.9 and Annex D, clause D 8a)
  • Society of Motion Picture and Television Engineers (SMPTE-DDE-1)
  • MPEG-4 is opening a work item on improved timed-text; the BIFS/VRML support is somewhat limited
  • FCC (Federal Communication Commission) and EIA (Electronics Industries Association) : captioning and teletext standards for television (US standards are the EIA-608 and EIA-708)
  • ITU (International Telecommunication Standardization)
  • The IETF AVT-WG may specify an RTP payload format for timed text
  • DAISY Consortium and NISO are working on a specification for Digital Talking Books that relates to the timed text format to be developed by this WG

Given the extensive existing body of work on Timed Text formats in other bodies, the WG should make an explicit effort to harmonize with one or more existing approaches. If possible, the WG should focus on the development of an XML-based representation that includes concepts of these approaches, since this is the "missing piece" in the standards that are available today.

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