"Alain" wrote on 1999-07-01 04:02 UTC:
> Btw SECAM is even superior to PAL...
This is not a particularly wide-spread view in the broadcasting
technology world, but details would certainly lead too far off-topic
here. PAL is currently being replaced by PAL+ anyway, which makes use of
modern digital comb filters for excellent cross-luminance supression,
and for which there doesn't exist anything comparable in the SECAM or
NTSC world.
SECAM = Sans Experience Contre les AMericaines
> That said, there is one thing (corect me if I am wrong) where NTSC is more
> democratic, and which brings a cultural goodie that PAL or SECAM do not
> bring in practice: live subtitles for the program dialogs...
European TV stations (particularly DE and GB) broadcasted subtitles on
teletext around a decade before the Americans started. The NTSC world
still hasn't any hyptertext text system embedded in TV signal that comes
anywhere close to the deployment of teletext in Europe. I only know of
some private initiatives (Intel has one on the market for instance), but
nothing anyway formally standardized or implemented on a broad scale.
Which brings us back to Unicode: Why aren't the teletext block graphics
symbols covered. I mean not all the obscure ITU ones that have been
registered at ECMA but that I have never seen used anywhere, but the
ones that have been implemented in practically every new PAL TV set
(except the lowest cost models) in Europe for the past 20 years? People
are receiving teletext also with PC adapters and currently need special
fonts to display it adequately.
Symbol tables can be found for instance in the data sheets of standard
videotext controller chips such as those produced by Phillips:
http://www-us.semiconductors.philips.com/acrobat/datasheets/SAA5X9X_FAM_2.pdf
(see page 52- ).
> The European standard privileges teletex pages but it is used mostly in
> hotels and is therefore not very democratic, not very practical... and has
> no big cultural impact.
This is a gross misrepresentation. Every European TV receiver (except
the very low-cost/portable end of the market) had built-in teletext
receiption capabilities since the early 1980s, and this is very widely
used in private households (even my technophobic mother uses it
regularly). Most stations have been transmitting an electronic magazine
with several hundred frequently updated hypertext pages for around 2
decades now. Common uses include reading news messages, checking the TV
schedule, looking up stock market prices, travel announcements, weather
forecasts, etc. The graphics quality is not great and reminds of the
early 1980s home computer displays (40x25 characters, 8 colors, 2x6
pixel block graphics characters, blinking possible). There is now a lot
of work underway to move for the new MPEG-based DVB digital TV standard
towards the ISO MHEG encoding for teletext, a new format that seems to
provide much more graphical and user interface capabilities than say
HTML. (MHEG = ISO/IEC 13522:1997 is certainly a new standard to have a
look at if you are interested in multimedia and hypertext, and I
wouldn't be surprised if also shows up soon in Web browsers as an
alternative to HTML).
What is true however is that in the US, subtitles are much more widely
used, even though the technology to receive them has been much longer
around in Europe. In Europe you get teletext subtitles only for a few
selected movies, and also only from the big public financed TV stations
such as ARD, ZDF, BBC, etc. The European private stations apparently
consider entering the subtitles on a regular basis (I understand they
are referred to as "close captioning" or so in the US) to expensive. I
wonder how this is financed in the US. Is there some legislative support
or even requirement to provide TV subtitles?
Does MHEG use Unicode and if yes, what Unicode subsets do MHEG profiles
for the currently starting European deployment projects use?
A few bits of information about MHEG 5 teletext in the UK are available
e.g. on
http://www.digital-teletext.co.uk/
http://www.fokus.gmd.de/ovma/mug/mtf/entry.htm
http://www.mhegcentre.com/mheg/tour.htm
http://www.cabot.co.uk/mheg.htm
http://www.mheg5.com/
Markus
-- Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
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