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Re: Digital TV
Just because something is compressed doesn't make it inferior
> quality, so comparing a 27MHz analogue signal with a 3Mhz digital
> compressed signal is largely meaningless unless you also know
> the degree
> of compression and the quality of encoder used (currently too much and
> too low).
The quality of the encoder is not an issue as the encoder is only doing
what
the MPEG standard is asking. All, well most, encoders for TV broadcast are
MPEG compliant and DVB compliant so the quality comes down to the
bandwidth
and only the bandwidth (OK, also the screen you are watching it on and the
human eye).
If a signal, picture is compressed then it has to be inferior as some of
the
components of the picture have been taken away on the encoding and and
replace with assumptions, i.e. this bit of sky is blue so this bit must
also
be blue.
Sky are putting up dynamically (Statiscally) multiplexed programming and
driving it to its limit. ie they should be putting up say 12 channels of
talk show or news programmes - this will give each channel around 2.5 Mb/s
on average - now some channel plays out F1 and bang their channel either
shoots upto 6 leaving the rest to flounder in picsilation or theirs justs
crashes. Quality is diminishing in broadcast and if they can put up 15
channels on one transponder compared to 1 HDTV on 3 transponders then the
premium channel is going to be very premium.
Quality costs and so do satellites - fibre, well that is another story and
hopefully be the saving grace to us public.
Ian
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