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TYPE 208 WIDE-SCREEN IDENT INSERTERTHE PROBLEM Traditionally, TV broadcasts have been in 4:3 aspect ratio. However, many programmes are now delivered in "wide-screen 16:9 anamorphic" mode via digital TV broadcasting, or from DVD playback. For more information about wide-screen TV, click here. A digital Set-Top-Box or DVD player signals to a wide-screen capable TV whether the programme is in wide-screen mode or not via a special wide-screen DC voltage level on the SCART connector pin 8, so that the TV can switch its scan size accordingly. However, if a programme is recorded on to a standard VCR, there is no way that the TV can know the correct display format when the tape is played back, and the TV display then needs to be switched manually to prevent the picture being the wrong shape. What is needed is a way of identifying wide-screen mode as part of the recorded video signal itself. THE SOLUTION The problem has actually already been solved. As well as the SCART DC switching, an international Wide-Screen-Signalling (WSS) ident signal has been introduced, as part of the video signal itself. It is inserted on line 23, an unused line in the Vertical Blanking Interval of the signal, just above the top-most part of the picture. The signal consists of digital data, somewhat similar in form to Teletext, but with a much lower bit-rate so it can be recorded on low-bandwidth domestic-quality VCRs. Most wide-screen-capable TVs can recognise this signal. Unfortunately many domestic wide-screen sources such as STBs and DVD players do not produce this signal, and rely only on the SCART DC method, which doesn't work with a VCR. THE TYPE 208 WIDE-SCREEN IDENT INSERTER
SPECIFICATION Input: Video and stereo audio on a standard SCART connector, from a wide-screen source such as a Set-Top-Box that uses Pin 8 signalling. Output: Video and stereo audio on a standard SCART connector with the WSS signal inserted on video Line 23 only when the input Pin 8 is in wide-screen mode. The input and output SCART connectors are fully wired, and thus support both RGB and S-Video signal formats, as well as composite video. Power: 12V DC on a 2.1mm DC power jack from a plug-top mains power unit (supplied). Dimensions: 185 x 145 x 42 mm approx. CONTACT US FOR MORE INFORMATION
© Amcro Technology Ltd 2004 Amcro Technology
Ltd.
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This is a compact DC-powered unit, designed
specifically to generate the Wide-Screen-Signalling ident
signal on Line 23 either for recording, or for the
passing of WSS switching through any video path that does
not permit the SCART Pin 8 DC switching method to be used.
It takes a standard SCART input from the STB, and
provides an output on a second SCART connector to feed
the recorder or TV, with the wide-screen Line 23 ident
signal inserted. The unit reads the pin 8 DC level input
from the STB to determine whether the WSS signal is to be
inserted or not. This provides a compact solution to the
problem of recording wide-screen material. When the tape
is played back, a WSS compatible TV then recognises which
parts of the recording are in wide-screen and
automatically switches accordingly. Note that as well as
16:9 wide-screen TVs, some newer 4:3 sets will recognise
wide-screen mode also, and reduce the picture height to
give a "letter-box" display.