HD1080i De-mystify HDTV 1080i ::: know why before you buy

Saturday, July 30, 2005

High Definition TV = 1080i

If you are a normal person, then this wide-screen LCD/Plasma flat 16:9 stuff looks like the way to go and you want one. So you read the ads and go to the store and check it out. Just about the time you realize you will need to plunk down $,$$$ investment in this, ... Panic should set in, there are too many options.

High Definition Widescreens. Some Facts.

What is 1080? Why does this number matter?
There is a world of new terms and stretched out images and slick sales talkers out there, ready to "yes" you into buying something. Since you have more questions than they can answer, you may well find that you are on your own. Lets break it down to the useful facts and make sure you know why before you buy, and get the most out if it when you do.

The most basic stuff:
You need to know resolution, or how many pixels make the picture. Each pixel is a group of red, green, blue elements.

1080 lines of resolution means 1080 rows of pixels from top to bottom of your screen with 1920 pixels per line across the screen from left to right.

HDTV is 1920 wide by 1080 high pixels in resolution.

Resolution: The "Other" HD is 720 lines
Basically, 720 line or 720p was created as an interim HD format and has the benefit of being 2 times faster in frames per second displayed. It is 1280 by 720 pixels and according to industry specs is considered HD. Typically a TV built (designed years ago) for this resolution is marketed with a 1366 by 768 display, and internal scaling up-samples the 720 lines to 768 lines to fill the screen. There are also 852 x 480 EDTV's that are big and wide and look like they may be high definition... but they are not.

Broadcast Formats: ?
ESPN HD = 1280 by 720p at a speed of 60 images per second.
NBC, Discovery, HBO = 1920 by 1080i at 30 images per second.
Cable providers may chose to only deliver 1080i in which case
source 720p will come converted to a 1080i signal anyhow.
( a movie theater film is 24 frames per second )

Native Resolution: What is Being Sold?
Although it is prfectly legal to say that a TV is "HDTV" or "HD-Ready" when it has less than 1080 lines of resolution, It really is the low-end of HD TV. I see this a lot. ex:

Xupersonic Plasma TV:Xx-wya421
Screen Size - 42"
Resolution - 1366 x 768 (HDTV)
I'm sorry, but 768 (720) HD is NOT the best HDTV.
CLICK::: your PC screen resolution next to HD 1080
Typically the larger Plasma TV's priced at $2500 on up are like this. They are easy to want beacuse they look great in the store, but they will NEVER display 1080 in all its pristine glory, which is the reason you wanted HDTV in the first place.

If you want truely stunning crisp HD - you need 1080 resolution.

Sellers are begining to know this too, and may well leave the native screen resolution out of the Specs they list. If you see NO resolution specs listed, then that is a clue to pass on it. If the display can do 1080i/1080p then they will surely list that.
Buyer Beware ::: Many of these TV sets will accept a 1080i input signal and then display it ok at 1366 x 768 which is 1/2 the number of pixels. WHY PAY HUGE $$ and get HALF the resolution?

Interlaced vs Progressive scan
This one annoys me, since the research you will get elsewhere indicates Interlaced content is not so good. WRONG. I will belabor the details later, but if you have a decent DVR/set top and or LCD HDTV, the picture you get to see is not interlaced anyhow. Most of the time each frame of an HDTV image is buffered by the system to make a full screen 30 times per second regardless of how it arrives to your system. The de-interlacing firmware that handles building the image is what matters, and most are so good you cannot see any problems. The Best in my humble opinion has the name DCDi by "Faroudja". Properly handled, interlaced source comes out rather like Film with a nice eye-pleasing motion blur where things move fast.

Bottom Line
The right stuff is a NATIVE RESOLUTION 1080i / 1080p system with Faroudja de-interlacing and filtering. Dont settle for anything else and you will be very happy with what you got.

... and you want the HDCP (DVI) in there since it is the right protection mode that your future HD-DVD and broadcast will use. TV's without HDCP will see junk when it goes into use.

The biggest problems arise in the system as a whole and that is where the details start to matter. When selecting an HD Monitor, resolution choices will muddy the water on selections.
There can be a big difference between what an HD Monitor is and what an HDTV is. The practical reality is that you want a TV that does all resolutions without a problem, technology options for managing that make the difference in what to buy, what to expect from it and how to use it. It is currently a Buyer Beware market, i'm here to help.

Paying Attention:
I have been visiting stores and making calls to check out the stock, sales person competence and what separates the good from the bad and the ugly... Just about every store had under-trained people that were more interested in selling that 3yr extended warranty than making sure i got a good answer to questions that i already knew the answer for. That's where the problem lies ( figuratively and literally ) and that is why i started this Blog. Even Mark Cuban says similar things, and he is probably the smartest straight talker out there. There is a definite need for a simple answer from an expert when it comes to making HD work today and into tomorrow, since most websites and sales people dump selectively chosen info on you.

Next: What is Component Input and why do you need and want that, Widescreen 16:9 is making people look at streched horizontally, LCD vs Plasma, Faroudja , HDCP, HDMI and your basic TIVO-like recorder, Blu-ray DVDs that actually deliver HD movies, and yes even that wedding video, and the future of independant videography ... There is more. lots more... Its all good and it is happening now.


Anonymous namartlu said...

Thanks for the article, lots of useful information.

I have been researching about HDTV, planning to get one. The confusion I still have, after reading yours and many other information on the net, is that when an HDTV displays an interlaced signal format (say 1080i), does it always do the de-interlacing? In other words, are there HDTVs that display tv in interlaced mode at all? Or it only happens in traditional CRT type TVs?

4:14 PM  
Anonymous Anonymous said...

Wow Jeff, Thank you for the
great information. My husband
and I know nothing about any
of these new tv's, you helped us
a lot. I have a question though,
our tv is and Akai and says it
is HD ready. What do we need to
make it ready? I don't trust
the untrained. Thanks Ray.

2:05 AM  
Anonymous Anonymous said...

Hello! Thank you for all of the great info. I actually got an Akai 1080 from a friend of mine. She was generous enough to let me buy it at a reasonable cost. However, I'm having major picture problems! The picture is green and pink, and it's showing double images. Any ideas???? I'm desperate! Thank you!


2:42 PM  

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