Thread: Home Theatre Blues - Part 6 (a): Choosing the TV

This article is aimed at helping you arrive at the right decision while choosing your display device, i.e., a television and in some cases the projector.

There have been many articles in the past on LCD TVs, LCD vs. Plasma, features to look for, etc. Some of the articles like the following are excellent:

The TV debate - LCD vs Plasma vs Traditional CRT
Buying guide to LCD TV

There are a few others too, some good, some trivial, while the others ... umm, let's leave at that.

In this article, I am not going to rant on which TV or brand or pros/cons. I shall just focus on the size and the type.

Since this article is dedicated to the home theater, this, sort of, automatically rules out CRT TVs. Not that CRTs are bad but to watch cinema, you need large size. At this moment, no one is selling CRTs larger than 29". Also, CRTs are usually not having progressive scan and this results into flickers associated with interlaced scan. Finally, the size is also a factor that goes against the CRTs.

This leaves LCD or Plasma TVs. Not dwelling on pros or cons of either, the main questions are:

• What should be the size?
• What should be the resolution? Should I go for HD-ready or full (true) HD?

Size
The answer is usually a no brainer. It depends upon the budget. But larger size means better for the experience, right? Interestingly, the answer is, "not necessarily". Not only the TV size should be apportioned to the room/viewing distance but it depends upon source content also.

Use the simple formula: Horizontal (not diagonal) width of TV = Viewing distance / 2

All LCDs/Plasmas are widescreen (16:9). So roughly, the horizotal width (length) of the TV (actual viewable screen), is diagonal width x 0.87.

So assuming the most common viewing distance for typical homes (6 feet or 72 inches), the TV can be 36" in length or 42" in diagonal. This is the maximum size and you could possibly go to lower size. But the smaller the TV, the lesser is the cinema enjoyment. And we should keep at the back of our mind that we are optimizing for the cinema and not TV.

p/s This is my own formula; there are some who may dispute the equation.

Resolution
HD-ready means a TV that has native resolution of 1366x768 with progressive scan or 720p. But such a TV can receive 1080i/1080p signals (1920x1080) and display them. This TV can display 480i, 480p, 720i, 720p and 1080i. 1080i or 1080p signal will be downscaled to 720i or 720p respectively by the TV. That is why it is called HD-ready which means the TV is compatible with HD but not truly HD.

A full or true HD TV has the native resolution of 1920x1080 with progressive scan or 1080p. Such a TV can display 480i, 480p, 720i, 720p, 1080i, 1080p. That is why it is called full HD.

Note that TV will not upscale the SD signal to HD.

The question here is HD-ready or full HD? The answer depends upon the source. If one is watching DVD and other SD content, an HD-ready TV should suffice. But BD players are now getting much cheaper and affordable. BDs are still expensive but you may soon find them in the rental library. And DTH is also set to go the HD way in India (Tata Sky to launch HDTV, more interactive channels this year- Electronics-Cons. Products-News By Industry-News-The Economic Times).

So it is better to be future proof.

So I shall recommend a full HD TV anyday. But your budget may restrict your sights to something lower. In this case, I will advise you to wait. TV prices have been coming down and with the same amount or with just a little extra (no more than 10%), you may be able to afford a full HD TV, six months from now.

One final word
When watching full HD content, the viewing distance make some impact. While full HD content on full HD TV will obviously look stunning, at a distance of 8 feet or more, the same full HD content on an HD-ready TV, may not make much loss of clarity.

For projectors refer here: Home Theatre Blues - Part 6 (b): Choosing the Projector

I had read on Anandtech about a new line of LCD TVs that were THX certified. Yes, THX certification for LCDs. They were expensive ($2000 for 52" LCD, mind you LCDs in the US are much cheaper)

also, once i had a look at a Bluray movie (Madagascar 2) at ezone on an HD ready and Full HD TV, both looked pretty good, but those were 32" LCDs so the difference (pixel pitch) would not be that apparent. But,at 42"+, HD ready TVs make no sense IMO.

Originally Posted by rajan1311

I had read on Anandtech about a new line of LCD TVs that were THX certified. Yes, THX certification for LCDs. They were expensive ($2000 for 52" LCD, mind you LCDs in the US are much cheaper)

also, once i had a look at a Bluray movie (Madagascar 2) at ezone on an HD ready and Full HD TV, both looked pretty good, but those were 32" LCDs so the difference (pixel pitch) would not be that apparent. But,at 42"+, HD ready TVs make no sense IMO.

Point 1:
THX is a certification for sound. It has nothing to do with video. So if some TV is THX certified, it means that it is certified for sound. It is a stupid idea. AVOID.

Point 2:
You are right in saying that it is pointless to buy 40"+ TV that is not full HD. But if all of the following are true:

• You are watching full HD content from a Blu-ray or equivalent source
• Your viewing distance of over 6 feet
• Your TV is 40" (diagonal) or less
• TV is either 720p (HD-ready) or 1080p (full HD)

then, you may not find much difference in quality.

BUT, if you move much closer to the TV, then there will be as much difference in quality (between HD-Ready and Full HD) as between chalk and cheese.

You missed my point.

Its THX certification for the PICTURE QUALITY and not sound.

The pixel pitch issue is very apparent when you are closer to the TV, that was true in my case(my father's place in dubai)

anyways, here is a link to the review of that THX certified TV:
AnandTech: THX Certified HDTVs - Useful or Just Marketing?

There is no such thing as THX for Picture. THX is for sound.

Originally Posted by just4kix

There is no such thing as THX for Picture. THX is for sound.

please read the article linked. Its just a quality standard spec.

Read the article. THX for TV is just a gimmick.

Originally Posted by just4kix

THX for TV is just a gimmick.

Hehe, thats what the whole article is about

hi just4kix,nice series of articles you are posting,keep up the good work.

i have some questions of my own.

1.what is the "minimum" screen size required to display 1080 pixel resolution without any image pixel compression or stretching?

and if there is a certain size requirement for full HD or 1080 pixel resolution,does it automatically mean that when a full HD image or video is displayed on a display "bigger" than the minimum size, it means that the image or video is stretched to fit the screen which translates to pixelization, not considering the viewing distance.

and if so, does it mean that going for a display size bigger than the "minimum" requirement for HD 1080 is of no use purely from a technical point of view unless of course one is planning to view extreme HD on the display?

2.an extension of the 1st question,why is it that some of the laptops (15") and even cell phones claim to have HD display.

3.why do close parallel lines get distorted or have some kind of illusion of moving when displayed in a moving video.i read it somewhere some time back,can't remember where,and it even said that TV reporters and anchors are told not to wear stripes.

please point me in the right direction.
cheers.

Originally Posted by iorhld

1. what is the "minimum" screen size required to display 1080 pixel resolution without any image pixel compression or stretching?

Theoratically is no such "minimum" limit. But to accommodate 1920x1080 pixels, there are practical limitations. An LCD pixel occupies some minimum space. As technology advances, the LCD pixel is getting more compact.

Two years ago, only 40"+ TVs could offer full HD. But since last year, 32" LCD TVs have also coming with full HD resolution panels. Maybe a year or so later, even 24" or 19" panels will be full HD.

Originally Posted by iorhld

and if there is a certain size requirement for full HD or 1080 pixel resolution,does it automatically mean that when a full HD image or video is displayed on a display "bigger" than the minimum size, it means that the image or video is stretched to fit the screen which translates to pixelization, not considering the viewing distance.

No. It is not like that at all. The LCD panel will have a fixed number of pixels. For full HD, these pixels are 1920 in number horizontally and 1080 in number vertically (for HD-Ready the pixels are 1366 x 768).

A bigger TV will mean bigger pixel size. Bigger pixel size means you have to be sitting that much away from the TV so that you do not see jagged edges.

Originally Posted by iorhld

and if so, does it mean that going for a display size bigger than the "minimum" requirement for HD 1080 is of no use purely from a technical point of view unless of course one is planning to view extreme HD on the display?

This does not apply. Currently the standard for hi-def is Full-HD. Perhaps in about seven or eight years we shall see this revised to Extreme HD (1440p). It should be noted that Super Hi-Vision (aka Ultra High Definition Television) at 4320p is also under experimetation in the labs.

Originally Posted by iorhld

2.an extension of the 1st question,why is it that some of the laptops (15") and even cell phones claim to have HD display.

Some laptops have a resolution of 1440x900 which is near equivalent to full-HD. Considering the size of the laptop screen (typically 14" or 15"), this is good enough to display full HD source without compromising the PQ. Hence they claim it to be HD.

No idea on cell phones.

Originally Posted by iorhld

3.why do close parallel lines get distorted or have some kind of illusion of moving when displayed in a moving video.i read it somewhere some time back,can't remember where,and it even said that TV reporters and anchors are told not to wear stripes.

This is actually an optical illusion and interlaced scan sometimes adds to the effect.

hi just4kix, please talk about LED TVs and its comparison with its counterpart LCDs and Plasmas. I guess LEDs are the future.

(Organic) LED TVs are still a way off and still evolving.

If you mean the LED TVs of today, these are not true LED TVs. They are LCD TVs backlit using LED light source. There is nothing to compare except that LED backlit LCDs are very thin.

just to add on, the true LED TVs (which are not going to be in the market anytime soon), will have much lower power consumption (some 80% less), will be slim, have a really fast response time (fastest LCDs I have seen have a 1ms response, LEDs will be about 0.01ms) and they will have much greater brightness, thats all i know.......but we are still pretty far, atleast another 4 years before we some mainstream LED TVs.

As J4K said, current TVs sold as LED TVs are NOT true LED TVs, they just have an LED backlight with an LCD panel.

oops...they are not 100% LED

Here were some queries by iorhld:

Originally Posted by iorhld

hi there,
i have some questions,need help.

to my knowledge,all the latest satellite DTH signals (like airtel,dishTV) are digital.when the STB is connected to an "analog" TV tuner card through S video or component video or whatever, does it mean the signal is being converted to an analog format and we just see analog TV just like the old analog cable minus the distortions caused by the transmission caused in case of analog cable.

Signal is converted from digital to analog.

Originally Posted by iorhld

The resolution of SDTV through a satellite DTH is 720 X 576, 4:3 @ 29 Fps,and if it is viewed on a 720 p computer display,theoretically will there be any difference in any quality parameter with the video when compared to it being viewed on a 720 p "TV" of the same size panel and aspect ratio.i am curious because i have heard some rumors (or call it marketing) that viewing SD DTH signal on a big screen TV produces better quality as opposed to a computer monitor of a smaller size,since all latest displays are good to go both as a TV or as a computer monitor, NOT TAKING INTO CONSIDERATION THE VIEWING DISTANCE AND VIEWING CONDITIONS.

satellite DTH is 720 X 576, 4:3 @ 29 Fps: This is just in theory. Although pixels and frame rate is still the same, the actual clarity of the signal depends upon the sampling frequency, bit rate and compression ratio.

The larger the display, the worse is the quality observed. So you will get much better clarity on smaller screen.

Originally Posted by iorhld

suppose a video is 640 X 352 P @ 29 Fps.how will the quality be affected if this video is viewed on a 720 P and a 1080 p display of SAME panel size, say 15.6 " diagonal.how much "BAD" effect does upscaling have on a SD video?

The monitor does not upconvert or down-convert. A lower resolution feed such as 480p to a high resolution display such as 720p or 1080p produces larger pixel size. In fact, it will appear worse off in this case. Try watching a VCD/DVD on a high resolution computer monitor and switch the mode to full screen. You will see artifcats. Same thing will happen for TV video.

Upconversion is different. It is basically "filling" missing pixels with colours best matching the surrounding pixels. It is a complicated process and the best results are only matched by high end Blu-Ray players such as Oppo BD-83, or costly AVRs, etc. Many low end DVD/BD players also offer this functionality but their upconversion is not that great.

upconversion = upscale ?
How do you rate that technology ? Worth spending the big bucks?

@just4kix
first off,thankyou for the reply and explaination.

so in case of viewing a digital DTH signal through a TV tuner card,the signal gets converted to analog,so basically it is just the transmission that is digital? is there any downside to this conversion,like degradation in signal quality just in between the STB and the display unit and if any,by how much? compare its quality parameters with analog cable.how is it different from PDTV? does it mean pure digital video from STB to display unit is possible only through HDMI cable?

i heard in japan,in earlier days of HD transmission,it was analog.so why is airtel making noise with their "digital technology", if analog HD transmission (in japan's case) is possible.i know going digital saves bandwidth,but if ultimately the DTH signal is converted to analog,so why make so much fuss about it? (i hope i put my words correctly to make the point i am actually thinking of).

i got proof of the second point you made about picture quality being dependent on sampling frequency, bit rate and compression ratio.i am posting a capture of two different videos of same episode,both from HDTV capture and ripped to 624 X 352,but one is 29.97 Fps and one is 23.97 Fps,same size file.the difference in image quality is visible clearly.
cheers.

Any conversion - be it analog to digital or vice versa - there will always be some loss. Digital to digital is possible via HDMI only.

As far as Airtel harping on "Digital technology", this is one of their advertising component. Analog transmission is prone to noise. For example, if you run two analog signals (wires) next to each other, the induction noise of each other will affect both of them. Digital signals are "more or less" protected from such interference.

THX might not just be a gimmick
well it can be used to calibrate the TVs, to get more of it

h**p://gizmodo*com/#!5098917/how-to-calibrate-your-new-hdtv-and-not-lose-your-mind

Good article........