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

Monday, November 06, 2006

HD1080i content vs less than 1080 screens

A quick review is good.. here you go:

HD1080i is a std format for HD DVD's and Broadcast High Definition. Its is 540 lines that arrive in screen odd rows and screen even rows, its then buffered and put together so that your display will assemble that in to a 1080 image, every 30th of a second.

540 @ 1/60th sec + 540 @ 1/60th sec = 1080 lines @ 1/30th sec

HD1080i is a full screen at 30 frames per second by simple math, but is actually displayed at 29.97 frames per second, for reasons of timing that stem from NTSC standards established in the previous millenia. This convention of odd and even display lines in broadcast is from the old CRT days, but it also provides a nice way to stream high bandwidth digital images, this is important because the digital packets have to handle 1920 pixels per line.

When we say HD1080i we mean 1920 x 1080 pixel display resolution.

The "i" means Interlaced, and that is just the method used to transport it to us, in odd/even rows rather than top to bottom in a single pass. Your HD monitor/display has to assemble that into each frame that you see. If it does that well then you see a great high def image.

Question:
A guy from Boeing asks: "how can hd 1080 be displayed at 768?"
Answer - it can but it isnt 1080 anymore.
Problem - 768 vertical pixels is greater than 720
Issue - 720 vertical pixels is an HD standard known as 720p usually.

so.. can they say HD and have a 1280x768 display or 1366 by 768 display? Yes... the display will scale its 1080i incoming stream of 2 megapixels down to the 1 megapixel resolution of 768.
e.g. more resolution arrives than your 768 display can show you.

so can they say that HD is there when the display is 768 vertical pixels? yes ... but it is being deceptive to say "accepts hd 1080i", or HDTV, and then show you something less than HD quality in pixel space.

everyone, even the usually trustable people are causing this problem.

Even engadget... http://www.engadgethd.com/2006/11/03/lgs-dual-screen-hdtv-equipped-refrigerator/

puleeze.. an HDTV-fridge? Nope. Why? - Display resolution.
anything 1024pixels in horizonal resolution does not qualify for HD. 1280 is the minimum number. So how do they get away with this?.. they install an ATSC HD capable digital tuner. Meaning; the co-ax for your cable or HD antenna connects to it, and it receives HD channels. However, what you see is not HD resolution, but HDTV channels at reduced resolution. I'm sure it looks great but it is NOT High Definition, it is HDTV channels at something much less than HD resolutions.

Confusing? Of course it is.

So what is HD? ... a digital signal path with an HD Transport Stream, displayed in at least 1280 x720 on up to 1920x1080 pixel resolution. For the HD experience to properly exist, all devices from beginning to end must be true to the spec.

Slapping a tuner (ATSC chip) that recieves HDTV signals into some device , and displaying it on a small low resolution screen is NOT HD, but it can be marketed by the slimy people as HDTV. They know that simply the HD connection is enough to sway buyers to a product. Its like naming a hotel "OceanView" when the hotel is 20 miles for any shoreline. Slimy.

OK WTF?
If you are a Consumer/buyer and wandered into this blog, then you are among the thousands that seek the right stuff and get a very mixed bag of junk to have to figure out... the odd thing is that i have been talking about bad marketing for over a year here now, and instead of that problem getting better, its is getting worse. There are more ugly bugs in HD marketing now than you will find in an African termite mound.

Blu-ray Delay
Trust me on this, you would rather they delay it than ship whats happening now. ' nuff said and i have no problem with that, its my belief that the 2006 seasonal buying experience doesnt need a massive January 07 crash and burn over HD player issues.

HD1080i
This is the broadcast format and std display of HD streams that will persist for the next few years, mostly due to bandwidth and compression efforts prepared for future use. The key thing for you to know is that interlaced HD source transport streams look great when properly processed at the disply endpoint, and basically its all good when that happens, the result is a progressive image that is delayed from actual arrival by mere milliseconds. This means component , DVI . HDMI basically should look quite good when done right and compatibility is not really a huge issue... for the moment anyhow.

HD-DVD
I have seen it, and really it is quite nice, notably clunky in initializing itself but basically it does its job well and the larger problems exist not in the format, but in the downstream processing and display its connected to. Kudos to the HD-DVD guys.

I made a pretty good demo reel in that format, actually it can play off a regular DVD too since its short in TRT, but basically i have proven to myself that there is no real problem at all in HD-DVD image quality and fast action scene-cut compression artifact recovery. If the Video editing. mastering / colorizer team does its job well, then you are going to love it.


HDMI 1.3
ok i caught some nooise on this....
Please... the 48bit color depth available in 1.3 is just not happening out there, so dont push this. Perhaps a dozen very uber-high end displays can even come close to 48bit color gamut at the pixel rendering right now, and in my opinion it is a false selling point. Joe sixpack wont buy a mountain climbing option for his SUV if he lives in a very flat floridian Keys area, since he knows he has no mountains around... 48bit color however sounds good and poor Joe has no clue, it isnt a mountain he can see, making it an unfair pitch.


Stuck Pixels?
ok you LCD HD display people .. tell me.
Does anyone have a stuck red-green-blue pixel dot on thier screen? Let me know.

Refresh & Frames Per Second.
The 720p60 issue that people have in displaying 1280 x720 resolution at full frames 60 times per second. get this, movies are displayed at 24 frames per second. not a problem. Normal TV in the USA is 29.97 frames per second. Unless following some ballistic sports is critical to you, 60 frames per second is useless overkill.

1 Comments:

Blogger Alexander said...

Actuallly, research shows that 1080i and 720p/60 carry about the same amount of image information. Say, we have a 1080i clip and a 720p/60 clip, both originated from the same high quality 1080p/60 source. Then when the 1080i is properly deinterlaced, and both clips are upscaled or downscaled to the same resolution, they both show about the same clarity. You will find links to actual studies at http://gadget-minded.blogspot.com/2006/11/hdtv-format-wars-720p-vs-1080i.html

2:21 PM  

Post a Comment

<< Home