120hz versus 240hz

[William Sommerwerck]

The 50 and 60 fields per second (a field being half an interlaced frame)

Well, the story I heard way back when is that it was to synchronise
the picture's vertical frequency with the mains frequency, so that
inadequacies in power smoothing produced static distortions in the
picture rather than much more noticable rolling distortions.

That's what I heard, too. But that's not "interefence effects from
electrical lights".

 

[Geoffrey S. Mendelson]

That's what I heard, too. But that's not "interefence effects from
electrical lights".

You are assuming that all interference would be on the screen itself and none
would be visual. Since flourescent and to some extent incandescent lights
blink (what is the persistance of an incadescent light?) at 60 Hz, there is
a strobing effect if there are lights on in the room with the TV.

While some peope (me) like to watch TV in the dark, many people watch TV's
with lights on. Some manufacturers went as far as to include light sensors
in their TV sets automaticly adjusting the brightness to compensate for
room lighting as it changes.

Since some people live in places where only flourescent lights are allowed,
they have no choice if there is interference, either turn off the lights
entirely, or live with it.

I guess that could be a new tourism slogan for this summer, "Visit Israel,
and bring home real light bulbs."

Geoff.

 

[William Sommerwerck]

That's what I heard, too. But that's not "interefence effects from

You are assuming that all interference would be on the screen
itself and none would be visual. Since flourescent and to some
extent incandescent lights blink (what is the persistance of an
incadescent light?) at 60 Hz, there is a strobing effect if there
are lights on in the room with the TV.

Incandescent lights have almost no flicker, due to the thermal inertia of
the filament. Fluorescent lighting was not common in living rooms at the
time the standards were set.

 

[William Sommerwerck]

But this isn't so. A crap picture may, I agree, look 'ok' to someone

I've seen plasma and oled. I can see differences between those and
standard LCD panels but not in my wildest dreams would I call them
crap. Most of my viewing is done in standard 480P 4:3 aspect cropped
to fill the screen. I don't need a high dollar plasma set for that, it
would be overkill. I own a Sony 720i/1080i HDMI upscaling DVDR that
produces sharp clear video. Once in a while I do notice a scan wave
because of the upscaling but the grand scheme of things make those
things very forgettable.

The 32" Vizio LCD in my den has a very wide viewing angle and does not show
significant smearing or blurring with rapid motion. (I paid about $380 for
it.)

With respect to scaling... People here and elsewhere have said they see no
point to Blu-ray disks, as they see little or no difference with upscaled
DVDs. Ergo, Blu-rays are a ripoff. I watched the Blu-ray of "The Sixth
Sense" yesterday, which threw this issue into sharp perspective.

The transfer is typical Disney -- extremely sharp and detailed, with rich
colors. It's close to demo quality.

Some of the supplemental material includes scenes from the Blu-ray transfer
that have been letterboxed into a 4:3 image. (Got that?) When I select ZOOM
on my Kuro, that section is blown up to full screen. ("The Sixth Sense" was
shot at 1.85:1.) Viewing at these images in isolation -- they look fine.
They're slightly soft, but one might believe it's the fault of the source
material. They don't look upscaled -- until you compare them with
full-resolution Blu-ray. There is no comparison!

 

[Chris]

The difference in resolution between the brightness and colour receptors
in human eyes, is well known and understood, but I don't think that this,
or any other physical aspect of the eye's construction, has any effect on
the way that motion is perceived from a series of still images.




Yes, I was not sure exactly why you were going into all of the colour
encoding issues in the context of LCD motion blur. This has nothing to do
with it. It is the display technology that is causing this. It is simply
not as good as other technologies in this respect, despite all of the
efforts of the manufacturers to make it otherwise ...




But this isn't so. A crap picture may, I agree, look 'ok' to someone who
knows no better, but that doesn't alter the fact that it is still a crap
picture that those who *do* know better, will see for what it is. LCD
panels produce crap images in terms of motion blur, and when compared for
this effect to CRTs, plasma panels, and OLEDs.




I was talking in terms of the fundamental visual principle in that they
are both matrixed cell-based displays requiring similar frame buffering
and driving techniques in signal terms. I was not referring to the way
that each technology actually produces coloured light from the individual
cells, which is clearly entirely different in both cases, from the raster
based CRT principle which, like plasma panels, doesn't suffer from motion
blur.





It doesn't really rely on the speed of the drive electronics since there
are techniques used to bring the plasma cells to a 'pre-fire' condition
just below the point at which the gas actually ionises. This allows the
cells to be fired with a small drive voltage, and without having to wait
for the cell to build up to the point where it actually fires. This is how
they can get the switching speed of the cells down to as little as 1uS



Hmmm. That's not the way I've seen it described. Most of the hype about
this development seems to concentrate on producing dynamic contrast
enhancement by modulating the LEDs' brightness in an area-specific way,
depending on the picture content in front of them.

Arfa

The way it was described to me is there are seveal hundred LEDs which are
each assigned specific "areas" of the screen. So it would seem that if you
have a bright AND dark area within an individual LED's jurisdiction, there
would be some sort of conflict. Unless, of course, such jurisdictions are
actually blended into the others. But they would still have to average their
brilliance. Either way, I could see how there would be a contrast
improvement across the screen as a whole since more lights is always better
than ONE.

 

[Phil Allison]

"Geoffrey S. Mendelson"

The 50 and 60 fields per second (a field being half an interlaced frame)
were
chosen not because they needed to be that fast (48 would have done), but
to
eliminate interefence effects from electrical lights.

** But the lights concerned were those being used to illuminate the TV
studio.

When frame rates are not locked to the AC supply frequency, faint shadows
can be seen moving up or down studio images on a monitor or home TV set -
due to the twice per cycle dip in brightness of incandescent lamps.

Other fixes include using lamps with sufficient thermal inertia or groups of
lamps on different phases to eliminate the light modulation.



...... Phil

 

[Geoffrey S. Mendelson]

The digital terrestrial TV being provided here in the UK now, currently
carries no HD content, despite ongoing promises. This is due to some extent
on the government reneging on a promise to make more of the UHF band
available to the broadcasters. Having now told them that they can't have any
more, and the broadcasters having already filled up what they have got
available with multiplexes carrying 'proper' channels and crap channels in a
ratio of about 1 to 5, the only option that they are now left with is to use
another different and non standard variant of mpeg 4 compression.

It's not nonstandard. MPEG4 is one of those "evolving standards", so that
they can sell you a decoder box or TV that supports the current variants
and next week turn around and sell you a new one.

Or if you have a computer, provide a firmware update.

It gets rid of the problem that CRT TVs had, they did not change fast enough
to get people buying new ones in a fast enough cycle to keep the companies
in business.

I have a spare TV that I bought in 1986 and AFAIK, it still works. We have
not yet switched to digital over the air here (Israel).

Speaking of MPEG4, Israel chose H.264 with AAC audio, a combination no one
had ever used before. The idea was to squeeze as many regular (520p 4:3)
channels in one 8mHz DVD-T channel.

The situation via direct broadcast satellite is much clearer. Here, they
have so much bandwidth available that they are able to carry many HD
channels, so this is where people here get their HD content from.
Unfortunately, the satellite operator charges us another tenner ($15) a
month for the privilege of receiving these transmissions ... :-(

Same here, but it's 40 NIS ($25).

BTW, where do those HDTV BBC programs come from? They are not over the air?

Geoff.

 

[Phil Allison]

"Dave Plowman (Fucking Nut Case Pommy **** )

Studio luminaries are commonly filament lamps.

** DUUUUUHHHHHHHHHH !!!!!!!!!!

WRONG CONTEXT - you fucking STUPID MORON !

In the UK TV hasn't been mains locked for about 40 years.

** WRONG CONTEXT - you fucking STUPID MORON !

Fluorescent types are used on location these days,

** WRONG CONTEXT - you fucking STUPID MORON !

Only time I've seen a phased array used was for a boxing ring

** WRONG CONTEXT - you fucking STUPID MORON !

Someone PLEEEEASE go and SHOOT this imbecile through the head !!!



..... Phil

 

[William Sommerwerck]

I'm not sure what exactly you mean by "an evolving standard".

That seems an oxymoron if ever I heard one. Either it's a standard,
or it's an evolving system. It can't be both.

To the best of my understanding, all audio and video codecs carry with them
the information need to correctly decode the transmission. This allows (for
example) DVDs and Blu-rays to use varying bitrates and different codecs. (If
this isn't right, please correct me.)

 

[Geoffrey S. Mendelson]

To the best of my understanding, all audio and video codecs carry with them
the information need to correctly decode the transmission. This allows (for
example) DVDs and Blu-rays to use varying bitrates and different codecs. (If
this isn't right, please correct me.)

No. It's much more complicated than that. AVI files carry imformation about the
file, such as a codec number each for audio and video, the bit rate,
the frame rate, number of audio channels, and so on.

Satellite (and DBS) data feeds contain some information, some feeds contain
none at all.

DVD's, Blu-Ray, VCD's, etc, all have a very specific format. DVD's are also
limited to MPEG-2 video encoding (with a limited range of resolutions, frame
rates, etc.) They also have a very limited range of audio encoding.

Sometimes it amazes me that a program such as mplayer or VLC can play a
random file and it works.

The reason the Chinese DVD players can play so many files now is that they
either use the freeware Linux based player, Mplayer, or the proprietary
clone of it written in a language for embedded systems.

Just as an example, someone gave me a sample of the files created by their
DVB-T TV decoder. They are raw MPEG-TS files, encoded with H.264 and AAC.
Nothing I have can open them. :-(

Geoff.

 

[[email protected]]

"Dave Plowman (Fucking Nut Case Pommy **** )


** DUUUUUHHHHHHHHHH !!!!!!!!!!

WRONG CONTEXT - you fucking STUPID MORON !




** WRONG CONTEXT - you fucking STUPID MORON !




** WRONG CONTEXT - you fucking STUPID MORON !




** WRONG CONTEXT - you fucking STUPID MORON !

Someone PLEEEEASE go and SHOOT this imbecile through the head !!!



.... Phil

You can do that yourself. The concept is simple - insert the muzzle
of the pistol in your ear and pull the trigger. If you are too stupid
to understand the concept, let me know, I'll gladly break it down into
a series of steps even you can follow.

PlainBill

 

[Mark Zenier]

So what band are we talking here ? Are these UHF digital transmissions ? How
many OTA HD channels would you typically have available in any given area ?
Do you know what compression scheme they are using ?

Both VHF-High (channels 7-13, 170something to 220? MHz) (3 stations, here)
and UHF (channels 14-51(?), around 500-700 MHz) (another 10, here).
There are some VHF-low band stations in other parts of the country
but I gather that 54-88 MHz has real problems with thunderstorms and
interference.

The US channels are all 6 MHz wide, both UHF and VHF. ATSC using 8VSB
with something around 19 MBPS, using MPEG-3. As I understand it, HD
will use about 12 MBPS. The over the cable version uses a different
modulation, [mumble]-QAM, and has twice the number of bits per second.
HD in the case of ATSC may be only 720p, or 1080i.

I can't get them all, (They're clustered in 5 different locations),
but at least 8 (maybe 10) are in HD.

The bucks from auctioning off channels 52(?) to 69 to the cell phone
and wireless companies is what got the government to push this through.

The digital terrestrial TV being provided here in the UK now, currently
carries no HD content, despite ongoing promises. This is due to some extent
on the government reneging on a promise to make more of the UHF band
available to the broadcasters. Having now told them that they can't have any
more, and the broadcasters having already filled up what they have got
available with multiplexes carrying 'proper' channels and crap channels in a
ratio of about 1 to 5, the only option that they are now left with is to use
another different and non standard variant of mpeg 4 compression.

Around here, since nobody had to be nice and share, they just toss off
a few crap channels when they shift to HD. (The PBS non-commercial
stations were about the only ones to do this, as they were early adopters,
and had their transmitters going long before they rebuilt their inside
equipment).

One of the things you have there, judging from the web pages I surfed
a while back, are the audio only transmissions from the various
national stations. I wish they had done that here, but most of the
stations that used to be combined radio and TV split up into separate
corporations back 15-20 years ago, so there no organizational connection
anymore.

The situation via direct broadcast satellite is much clearer. Here, they
have so much bandwidth available that they are able to carry many HD
channels, so this is where people here get their HD content from.
Unfortunately, the satellite operator charges us another tenner ($15) a
month for the privilege of receiving these transmissions ... :-(

Sounds cheap to me, I gather you can spend $90 a month (not including
pay per view) to get the full load. Minimum, $30-$40 a month.

Mark Zenier [email protected]
Googleproofaddress(account:mzenier provider:eskimo domain:com)

 

[Geoffrey S. Mendelson]

Sounds cheap to me, I gather you can spend $90 a month (not including
pay per view) to get the full load. Minimum, $30-$40 a month.

It is cheap. The 10 quid (UKP) is an EXTRA fee for HD. You buy whatever
package you want, and if you want HD, you buy the HD package, which is a
few channels in HD.

Most channels are not available in HD.

Here for example, the DBS system I use has 4 movie channels, in HD they have
one. If you want all four channels, or a different movie than the HD channel
is showing, you have to watch it in regular, which means you had to pay
for that channel.

Regular def here is a mixed bag, about 10% of the programs are 16:9, most
are 4:3. The decoder box gives you a choice of always 16:9 (which means the
TV set has to detect the difference and switch), always 4:3, or letterboxed
16:9 on a 4:3 set.

I have no idea of what really is on HD, I don't have a TV capable of it.

Note that if I were to upgrade to an HDTV, I would not upgrade the service,
I get so much of my program material from other sources, it's not worth it.

Geoff.