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 subtitling of foreign-language movies on the

Web Web most often refers to: * Spider web, a silken structure created by the animal * World Wide Web or the Web, an Internet-based hypertext system Web, WEB, or the Web may also refer to: Computing * WEB, a literate programming system created by ...

, captioning for people lacking audio devices or having

hearing impairment Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken la ...

karaoke Karaoke (; ; , clipped compound of Japanese ''kara'' "empty" and ''ōkesutora'' "orchestra") is a type of interactive entertainment usually offered in clubs and bars, where people sing along to recorded music using a microphone. The music is ...

, scrolling news items or

teleprompter A teleprompter, also known as an autocue, is a display device that prompts the person speaking with an electronic visual text of a speech or script. Using a teleprompter is similar to using cue cards. The screen is in front of, and usually be ...

applications. Timed text for

MPEG-4 MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related t ...

movies and cellphone media is specified in MPEG-4 Part 17 Timed Text, and its

MIME Multipurpose Internet Mail Extensions (MIME) is an Internet standard that extends the format of email messages to support text in character sets other than ASCII, as well as attachments of audio, video, images, and application programs. Message ...

type is specified by RFC 3839.

Markup language specifications

The W3C keeps two standards intended to regulate timed text on the

Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, p ...

: the Timed Text Markup Language (TTML) and WebVTT (currently in draft stage).

SMPTE The Society of Motion Picture and Television Engineers (SMPTE) (, rarely ), founded in 1916 as the Society of Motion Picture Engineers or SMPE, is a global professional association of engineers, technologists, and executives working in the m ...

created additional metadata structures for use in TTML and developed a profile of TTML called SMPTE-TT. The DECE incorporated the SMPTE Timed Text in their

UltraViolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

Common File Format specification.

Competing formats

Interoperability for timed text came up during the development of the 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 English closed captioning file, in

SubRip SubRip is a free software program for Microsoft Windows which extracts subtitles and their timings from various video formats to a text file. It is released under the GNU GPL. Its subtitle format's file extension is .srt and is widely supported. ...

format, for the 1916 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 TTML is the following: I'll teach thee Bugology, Ignatzes Something tells me Look, Ignatz, a sleeping bee

References

External links