Re: blocky picture on new HD tele


"Roderick Stewart" <escapetime@xxxxxxxxxxxxxxxxxxxxxx> wrote in message news:t1uk839b4q8pbcuh0lnq2djf1lgcm8ruqv@xxxxxxxxxx
On Tue, 3 Jul 2007 14:17:21 +0100, "Agamemnon"
<agamemnon@xxxxxxxxxxxxxxxx> wrote:

i just got a new HD tele at the weekend and plan to get an upscaling dvd
player in a few weeks. at the moment i am using just my standard dvd
player
and have it connected to the tele with a good quality scart lead.

at first i thought the dvd picture was ok but after watching it for a bit
i
just thought something wasnt right. i got closer to the tele and saw that
whenever something black was on the screen inside that black would be a
whole lot of light coloured blocks shifting around! i get the same thing
on some Sky channels too. in dark scenes the picture looks a lot like a
negative of a photo.

That's because the psychovisual profile of MEPG is complete and utter
bollocks. The designers of MPEG created it based on the misconception that
people are less sensitive to dark colours than they are to bright ones and
thus encode dark parts of the picture with a lower bit rate than bright
areas. The idiots though messed up so that even when the entire image is
dark it still gets encoded at a lower bit rate when this is not even
necessary. On top of this people are not less sensitive to dark colours than
they are to bright ones. Once they get used to the dark they become more
sensitive to dark colours, as you have just found out, even when they are
side by side with bright areas.

They also seem to have the misconception that people are not sensitive
to different parts of a moving picture moving at different rates. Am I
alone in finding it extremely disconcerting when somebody turns their
head or nods, and their face moves as if it were a mask made of
several separate pieces held together with jelly?

Nope. I've noticed the same thing myself, in tact, only a few minutes ago I finished watching the first 3 episodes of Jekyll (since the tennis was rained off) which I recorded in Xvid and it was full of it. The noise on the images wobbled like something smeared over molten plastic and every time a key frame was inserted the plastic became solid again and the smearing disappeared. It was really annoying. MPEG-4 is worse at this than MPEG-2. No wonder HD-DVD has gone down the toilet as far as video rental is concerned in favour of Blu-Ray which uses MPEG-2.

I guess they just
never invented a measuring instrument that would respond to this, so
objectively speaking it doesn't exist, but a pair of human eyes
looking at a human face is a different matter.

I am still trying to find a cure for it. Does anyone know how to set the Xvid codec to reduce it?

I think I'd rather have
grainy analogue with a bit of ringing and a few ghosts - at least the
technical deficiencies look technical, and not like some spooky
behaviour of the image itself.

Considering that ringing is inherent in the way MPEG encodes things analogue is clearly superior. On top of that analogue is broadcast in 4:2:2 colour space whereas Freeview and HDTV is broadcast in 4:2:0 colour space therefore analogue is of a higher definition than 720 line high definition TV.

Rod.

.

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