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On digital terrestrial television in the UK there is a legal obligation to provide signing for deaf viewers for some programmes. Sign language comprises the use of manual gestures, facial expression and body language to convey meaning. British Sign Language (BSL) is the most popular sign language in the United Kingdom, but Sign Supported English (which tends to follow the syntax and vocabulary of English) and Makaton (a simplified form of sign language sometimes used with deaf children) are also used.

Since having a signer taking up a considerable portion of the picture area can detrimentally affect the enjoyment of those viewers who don’t need the service, the preferred method of signing is to use a human signer transmitted on a separate ‘channel’, with the signer’s picture displayed in a corner of the display. Perfection would probably be to show the signer as a full resolution digital video image that can be switched on or off, adjustable in size, and positioned in various parts of the screen at the choice of the user. At the moment the amount of data available in any digital channel for signing is so restricted that this type of ‘closed’ signing (i.e. that can be switched on or off at will according to the viewer’s wishes) can only sensibly be reproduced by the use of computer generated cartoon-like ‘avatars’, and many deaf people (or perhaps more truthfully the organisations representing them), feel that this gives them a worse service than they deserve.

Improved compression and the future new DVB-T2 transmission system could provide the extra capacity to carry signing as a proper digital video signal.

Ofcom recommendations for signing include:

Checklist for signing




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