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Television broadcasting - subtitling standards
- TeleText
- TeleText was developed by the BBC in the 1970s. Today, it is used throughout
Europe, Asia, Africa and the Pacific, primarily with PAL and SECAM systems.
TeleText is an information service organized into pages,
numbered from 200 to 700. These pages cover a wide range of topics
including television schedules, local news, market prices, local and tourist information
and more. Subtitles are typically transmitted on page 888 in
the UK, on pages 199/299/399 in Belgium and Holland, on page 150 in Germany and
on page 777 in Italy. There are a number of variant character sets used, but the
encoding is identical and all English alphabet characters plus numbers and most
punctuations can be handled by any decoder. Teletext also includes support for 8 colors
and limited block graphics. TeleText transmits on a variable number of lines
(specified in header containing basic information such as time, date and channel),
starting on line 12 and continuing for 7-8 lines typically.
- CC - Closed Captioning
- This is the North American counterpart of TeleText developed in the United States
through political pressure from the deaf organizations in the 1970s.
Closed Captioning is primarily used with NTSC systems in North America and parts of
South America. Closed Captioning transmits on line 21 of NTSC/525 transmissions,
and contains subtitling information only. CC has no support for block graphics or multiple pages but it
can support 8 colors and the use of an italic typeface.
- CaptionVision is an extended service of Closed Captioning. CaptionVision adds a capability
to transmit items like station call letters, network names, program titles, program descriptions,
intended age level of program, content advisories, time of day, and weather news and emergency warnings.
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