Timed text is the presentation of a text medium in synchronization with other media, such as audio or video.
Typical applications of timed text are, for example, real-time subtitling of foreign films on the Internet, subtitles for users without audio devices or hard of hearing, Karaoke, treadmills with news or teleprompter applications.
Timed text for MPEG -4 movies and mobile media is described in MPEG -4 Part 17, and RFC 3839 is referenced.
W3C develops a Timed Text ( TT ) specification, which includes many aspects of timed text on the Internet. It was introduced as a W3C Recommendation.
The question of the development of a interoperabilen text format came up during the development of the SMIL 2.0 specification. Nowadays, there are quite a few incompatible with other formats for image, text, subtitling and other timed text formats that are used on the Web. This means that the text part when you create a SMIL presentation, often has to be forwarded to a particular playback environment. This poses a problem when creating interoperabiler SMIL presentations. In addition, the hearing impaired are very dependent on subtitles to make it accessible to audiovisual content for the hearing-impaired viewers. The absence of a interoperabilen format adds significant additional costs to the already existing high cost of closed captioning of Internet content added.
Timed Text enriches the user experience of services that are associated with Timed Text, and is used as an important stimulus for example in the use of captioning and subtitling. Among the organizations that want to work on Timed Text, are such as streaming multimedia technologies, web browser companies, representatives of the deaf community, producers of subtitles and manufacturer of consumer electronics.