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.
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Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or
understanding, as in he has a sub-wikipedia understanding of the situation.
i.e possessing less facts or information than can be found in the Wikipedia.
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.
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.
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!
60 Hz ws used in the US to prevent hum bars from rolling up or down the screen due to the difference in the line & scan frequencies. A faint bar would be hard to spot if it was not moving, but very annoying if it did. People have to remember that the standards were set when Electronics was fairly new, and rather crude designs were used.
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.
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 ?
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.
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 ... :-(
** 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.
Not so. BBC HD is transmitted on FreeView as is ITV HD. CH4 and 5 will be added shortly. This is from the London transmitter. Not sure about everywhere.
--
*Who are these kids and why are they calling me Mom?
Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
Studio luminaries are commonly filament lamps. To allow easy control of level, and because of their continuous spectrum light output.
In the UK TV hasn't been mains locked for about 40 years. I'd guess other countries the same. The mains frequency varies too much for modern requirements.
Fluorescent types are used on location these days, but use high frequency ballasts. HID types don't run at mains frequency either.
Only time I've seen a phased array used was for a boxing ring - before high frequency ballasts became common.
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*I pretend to work. - they pretend to pay me.
Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
None available on FV here in my east midlands location. Just looked at my "TV Times" (national) listings mag, and it claims that BBC HD is available on Freesat CH 108, Sky CH 143 and Virgin Cable CH 108. Likewise, it says that ITV HD is only available on Freesat via the 'red button' service. In any case, BBC HD is hardly a useful service, as they just stick a mixture of their total network output on there at random times. I was recording "Survivors" on BBC HD via sat on series link. Suddenly, the series finale has disappeared from the recording list. I check the schedules, and it's just not on there. Some random olympics programme or something. So I hastily set it to record on SD BBC. Then, a couple of days later, it randomly appears again on BBC HD at some obscure time when they had a slot to fill. ITV HD, from what I've seen of it on the Freesat service, seems to be just for football matches, once in a while. Either service is hardly inspiring for people with HD TV sets and a built-in DTTV tuner, as most have.
So I would have to conclude that at the moment, the London area is possibly unique in carrying these services. Just as a matter of interest, what equipment is required to receive these FreeView HD transmissions, and has the compression scheme now been finalised then, to allow manufacturers to produce necessary equipment in bulk ?
Interesting that you say that CH5 is shortly going to be placing HD content onto FreeView. At the moment, they have no HD output at all, and I would have thought that if they were about to start, then the first places would have been on the Sky satellite service, and Virgin cable, where there is an existing customer base, with fully operational equipment to allow them to access and view the service.
Channel Four I can understand wanting to provide a FreeView service as they already produce an HD mirror of their SD service on Sky and Virgin.
Just as a matter of interest, do you know what cameras they use for producing their HD content (or their programme makers / suppliers) ? Just that their HD output is stunningly good compared to some other efforts by other stations. And I'm talking original 'native' HD here, not just content that was shot in standard res, and then placed on the station's HD channel. Taking, for instance, Phil and Kirsty's "Relocation, Relocation" (Wednesday
8pm) programme on CH4. The image quality is absolutely cracking, and everything you would expect HD to be. Likewise, "Extreme Engineering" on NatGeo I think it is, and "American Chopper" on Discovery. OTOH, "Lost" and "24" from Sky 1 both claim to be 'originals' in HD format, but although they look better in HD than they do in SD, they still seem to lack that 'pin-sharp' quality that the other programmes I've cited, have. As you are 'in the business' so to speak, just wondered if you had any insights into this ?
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.
Same here, but it's 40 NIS ($25).
BTW, where do those HDTV BBC programs come from? They are not over the air?
Geoff.
--
Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or
understanding, as in he has a sub-wikipedia understanding of the situation.
i.e possessing less facts or information than can be found in the Wikipedia.
BBC HD is currently available by direct broadcast satellite, and from the Virgin cable service. I receive it via the former. It would seem that in a few areas, it is now available via the FreeView DTTV service which is replacing our current analogue service over the next couple of years. However, although I receive FreeView from one of the 'main' national transmitter sites, the FreeView HD service will not be available to me for some long time yet, according to
formatting link
A different DTTV receiver is required, and it looks as though the only one currently available is 180 quid ($270 ish). I can't see many people wanting to hang yet another receiver on the end of their 'HD Ready' TV sets, for that sort of money, and to receive just a few HD services. There is never going to be the bandwidth available to put more on there, alongside the other services.
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. The sat broadcasters have been using the same transmission standards for years, and don't seem to suffer problems with compatibility of receiving equipment. The DTTV service, OTOH, seems to be a mish-mash compromise system, which has changed 'standards' and names several times, in an effort to make it do what was, in truth, never going to be practically possible ...
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.)
They're really just tests at the moment. The full HD service should be available by the Olympics next year.
Well, I don't have a FreeSat receiver but get ITV HD off satellite.
With just the one HD service, choices will be made.
Some dramas too. The most regular being The Bill.
I'd be surprised if many have an HD set with a built in HD tuner - they've only just been announced. And an ordinary Freeview tuner won't get HD.
FreeView HD tuners are on the market. But I'll not get one until there's a HD PVR at a reasonable price.
The relationship between Sky and its audience is based on making Sky money. Nothing to do with providing a service.
I'm not sure what gear is used for the progs you mention. But the snag is some still use filters to soften the image - especially with 'talent' of a certain age who don't want every wrinkle to show. Near always on drama. However, anything shot outdoors to look good is likely to look particularly sharp due to the light levels than drama, etc.
The HD drama I work on uses Thompson cameras and is recorded on Panasonic P2 - memory card based system. The pictures are quite superb - until the fog filters go in. ;-(
--
*Corduroy pillows are making headlines.
Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
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.
--
Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or
understanding, as in he has a sub-wikipedia understanding of the situation.
i.e possessing less facts or information than can be found in the Wikipedia.
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