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When is 720p Not 720p?
Henning Hoffmann writes "HDBlog has an interesting entry about many home theater displays.
Home theater displays around the resolution of 720p (most DLP, LCD, and LCOS displays) must convert 1080i material to their native resolution for display. No surprise there. But many displays do this by discarding half of the 1080i HD signal, effectively giving 720p viewers an SD signal - not watching HD at all! "
Home theater displays around the resolution of 720p (most DLP, LCD, and LCOS displays) must convert 1080i material to their native resolution for display. No surprise there. But many displays do this by discarding half of the 1080i HD signal, effectively giving 720p viewers an SD signal - not watching HD at all! "
This sounds like the visual version of what Creative Labs has been doing for YEARS with their Sound Blaster audio cards. With most other cards if you want to record with a sample rate of 44.1 khz, you record at 44.1 khz, but even with the newer Sound Blaster cards it must be resampled to 48 khz first.
It doesn't matter if you are sampling up or down, resampling is bad, your best b
et is to find a device without it, or if it is necessary like in this case, the one that does the best conversions.
If I bought one of these displays I would be pretty pissed, but I doubt there is much that can be done about it, if you COULD do something than companies like Creative Labs would be out of business.
Use a HTPC and a RGB or DVI input for the display. The HTPC will use the Video card to process the signal. Programs like VideLan have modes to properly format the video. Case Solved?
...When converted from pounds Sterling to Euros?
Paleotechnologist and connoisseur of pretty shiny things.
Come on giants! I am waiting for your answers!
No sig for now.
No surprise there. But many displays do this by discarding half of the 1080i HD signal, effectively giving 720p viewers an SD signal - not watching HD at all!
The HD signal's still there... you just have to learn how to read between the lines.
Here is tfa for you...
When is 720p not 720p?
Tom Norton, in his coverage of the Home Entertainment expo, brought something up that I was unaware of.
720p displays show native 720p signals directly, of course. They also upconvert SD signals (like DVD) up to 720p for display. And 720p displays must convert incoming 1080i signals to 720p before they can be displayed. No surprise there, this makes sense. But, Silicon Optix claims that most manufacturers do the 1080i conversion just by taking one 540 line field from each 1080i frame (which is composed of two 540 line fields) and scaling that one field up to 720p, ignoring the other field. Reason being, it takes a lot less processing power to do this than to convert the image to 1080p and scale that, which would use all the information in the original signal to derive the 720p signal. If you have a display like this, it means that you're watching 540 lines of resolution upconverted to 720p. This is not HD, just like watching a DVD upconverted to 720p is not HD. Sure, you'll get the full width of the 1080i resolution, but you're only getting half the height. While this is better than DVD, it's not HD in my mind. (Aside: Tom Norton mentions this in his review of the Screenplay 777 projector.)
If this is indeed the case, most people with 720p (or similar) projectors (and most DLP, LCD, and LCOS home theater projectors are exactly that) are not seeing what their displays are capable of. They're not, technically, even watching HD. This is crazy! How can this be? Why haven't we heard of this before? How are manufacturers getting away with it?
Over-reacting? Well, if you're an owner of a 720p (or any similar resolution) projector you're either gonna be really upset by this or you're just gonna be laisez-faire about it because there's nothing you can do and you're enjoying your projector just fine thank-you. But me, I don't even own any such projector and I'm a little ticked. But I guess I should really wait for evidence of how properly-done conversion looks in comparison before making any snap judgements. I'm sure that the people selling HQV (a processor chip that does it the RIGHT way) will set something up.
To me, this is a serious issue. Comments are welcome.
from: http://www.hdblog.net/
There's got to be a fairly straightforward formula relating inherent resolution loss when performing any noninteger upsampling, or any downsampling. Any other change in resolution must necessarily degrade the signal, yes? (Except perhaps if a clever algorithm could losslessly encode the original data in a 1.5x-upsampled version, without distorting it.)
Paleotechnologist and connoisseur of pretty shiny things.
Is there any way of telling which sets do this? This is certainly something I'd like to know before I dropped that kind of cash.
"Ask not what your country can do for you." --John F. Kennedy
720p is not 720p when its not 720p. Got it?
Oh, I think I'm getting a little misty over here. Its just so sad..all those 720 owners, watching tv at slightly less quality than HD, its just so....heartbreaking.
In other words: cry me a river.
-d
"Here Lies Philip J. Fry, named for his uncle, to carry on his spirit"
A Home Theater PC with good quality parts, drivers, and decoders will preserve the 1080i signal - it will combine the 1080i field pair into a single 1080p signal, and then downconvert (ie. downscale) to 720p.
As a reference, my Athlon XP running at 2.4 GHz (aproximately equivalent to an Athlon XP 3400+) with a Geforce 6800GT and TheaterTek 2.1 software will have (little) trouble achieving this, assuming the 1080i source isn't glitchy itself.
Alternative is to use the NVIDIA DVD Decoder version 1.0.0.67 ($20 US after 30 day trial) and ZoomPlayer 4.5 beta ($20 beta or nagware) for similar results.
TheaterTek is roughly $70 US and includes updated NVIDIA DVD Decoders - too bad NVIDIA hasn't updated their official DVD decoders with the bugfixes that is present in the TheaterTek package.
When the un-washed masses can't actually tell the difference (they can't even see DCT blocking) and you can get away with selling this crap to them..
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I have a 720p projector paired with a 110" screen. Both 720p and 1080i material look fantastic. Maybe the supposed degredation would be visible side-by-side with a native resolution projector, but I certainly wouldn't worry about it based on what I've been watching.
get nemulator
I had the same line of thought, that if you just use an HTPC and a monitor that can display data from that (like a projector) then you are all set - as long as whatever feeds HDTV into your HTPC for display is properly doing the conversion. That would be interesting to know, how are current HDTV cards for PC's doing any scaling? I guess they just dump the ffed to disca and then it's up to the players, which hopefully use the great horspoer of a PC to scale properly...
"There is more worth loving than we have strength to love." - Brian Jay Stanley
The article says: Sure, you'll get the full width of the 1080i resolution, but you're only getting half the height.
Except your 720p display will hopefully have a horizontal resolution of 1280. 1080i video has a horizontal resolution of 1920. So, you're keeping half of the vertical (1080 lines to 540) and you;re keeping 2/3rds of the horizontal (1920 down to 1280).
Ouch.
When I upgrade to an HD idiot box, I plan on sticking with tried-and-true CRT. IMHO, you can't beat the picture quality/price, and I have yet to hear a compelling reason to fork out thousands of dollars for the trendier offerings.
"Ask not what your country can do for you." --John F. Kennedy
Early adopters often get slapped in the face. I've been thinking about buying an hdtv for a long time. I'm really glad I read this before I bought one.
You can tell I'm an aries because of my ram.
What's sad is that the engineers for these companies are keeping quiet. What ever happened to having ethics for your profession?
This is what you get when you buy a "major" appliance without doing your research first. I know if I was planning on dropping anywhere from $700-to over a $1000 on something, I would be sure to find out everything about it so I could make an informed decision. If someone didn't do that, then they got what they deserved.
That said, I'm sure there a lot of people out who "don't care". It works form them, and that is all they care about.
I'm very responsible, when ever something goes wrong they always say I'm responsible.
It would be nice to know what chip or products use this type of conversion. Currently I have my Motorola STB convert everything to 720p. This setup did seem to product a better image than letting my Panasonic LCD Projection set handle the conversion.
These people look deep into my soul and assign me a number based on the order I joined.
If the broadcast is 1080i, and your display isn't 1080i, I don't think it's logical to assume the quality of the downsampled video will be equivalent to a true 720p broadcast.
When I get around to buying a HD television (not any time soon, I do all my televisioning on my computer), it will be a true 1080i (are there 1080p televisions?) display so I'll know I'm getting the full potential of HD.
Unless I'm strapped for cash, of course, in which case I'll just suck it up and know my 720p won't be the best thing for watching 1080i content on.
On the plus side, it's important to get the facts out there for the consumer, who will likely (although not logically) assume he's/she's getting more than they really are.
You will also need a decent HDTV tuner card - but, I don't know much about them. http://www.avsforum.com/ is the place to go if you need info on that.
Unfortunately, since I live in Calgary, Canada, HDTV service is very sparse...I basically download HDTV 1080i content from the internet - usually trailers or free NASA HD content.
Why not submit a link to the original article, rather than a link to your blog, which consists only of a link to the original article?
Otherwise, people might assume this is a shameless attempt to draw traffic to your site.
Which set-top (cable/satellite) receivers are doing that same stingey conversion when you've told them to output 720p?
Anyone with any real regard for picture quality, and whose equipment leaves them the choice, has probably evaluated it under both configurations anyway.
NDA
From my lurking on HDTV enthusiast sites, sometimes the broadcaster will take DVD content (480i) and upconvert to 1080i! It's a terrible practice.
And in other instances, the broadcaster will not use the full resolution - what looks like 1920x1080i may actually be an upconvert of 1280x1080i, 1440x1080i, or 1280x720! And then there is the overcompression - taking a 20mb/sec mpeg2 stream and cutting the bitrate in half - compression artifacts galore.
It is sad when HDTV programming available in North America can be WORSE than the DVD!
You never know what you get in US (and other?) HDTV broadcasts. My understanding is that only the Japanese use minimal mpeg2 compress - I saw snippets of Contact (with Japanese subtitles) in full glorious 1920x1080i at the maximum 20 mbit/sec bitrate - and it was glorious!
This is the reason I bought a 52" rear screen projection than LCD/Plasma and whatever. That, and it was 3000 bucks cheaper and had a better picture.
Supporting World Peace Through Nuclear Pacification
Ok, here's the skinny. 1080i is 1920x1080 @ 59.94 fields / second, meaning at any one instant in time, you're looking at a 1920x540 image made up of every other line of the picture (the odd fields, if you will.) Then, ~1/60th of a second later, you see the even fields. 720p is 1280x720 @ 60 FRAMES per second, meaning at any given instant you're looking at EVERY field of the image...not just the odd or even fields. If you were to try and take all 1080 lines from the original signal, they wouldn't really map properly to 720 at any given second because half of data would be from that same ~1/60th of a second later. Scaling the fields up is really the best way to go, at least for stuff that's been shot interlaced.
And when you use it to upsample data, it is a lossless encoding that doesn't degrade the signal (unless you deliberately throw away data - discrete Fourier transforms are also used in lossy encoders).
It's not a distortion-free transform, since high frequency signals (e.g. sharp edges) in the original image get interpreted as smooth changes and can get blurred between multiple pixels in an upsampled signal. But then again, that's exactly the sort of thing that happens when you digitize a picture in the first place - if you have a sharp black/white edge that passes through the middle of a pixel, the most accurate thing you can do is make that pixel gray.
I haven't had a chance to read through the full article/blog/whatever yet (I'll do that at lunch), but this sounds like something I noticed over the weekend while browsing the Best Buy site. Companies are now producing ED-compatible TVs. They list all sorts of compatible display modes (1080i, 720p, 480p, etc), but then mention that they downscale them for display on the TV. Is this just some way of offering half-assed support to unsuspecting consumers?
I'll turn into a supernova and burn up everything. Well I'll turn into a black little hole and you'll turn into string.
Which can also be the only explenation for why anyone would try to encode HD-content on todays DVDs.
I can't understand anything else than that the DCT-artifacts would be even more dominant than on todays DVDs (or DVD-rips).
Not Buzzword 2.0 compliant. Please speak english.
:)
Basically, you want to bypass your projector's scaler. If the display hardware always passes 720p resolution to your native 720p device (preferably using DVI OR if you know your display won't rescale 720p to 720p - yes, some do this horrid practice!) then you will avoid the problem.
To those of you screaming "I'm glad I didn't yet buy an HDTV... Foolish early adopters..."
1. It's not the TV's problem. It's the processor feeding the TV. Most HDTV's don't have the processor/scaler on board. This is done with your CABLE BOX, SAT RECEIVER, or [upscaling] DVD player.
2. 1080i... Who cares? 1080p is where it's at... If you're on the fence about buying into HDTV, then wait until you can buy a 1080p capable unit.
3. Stick with CRT? Why pay more for old technology? Some of the newer LCos, DLP, and LCD solutions can draw a BETTER picture for less money and certainly less maintenance (convergence!??? NEVER will I deal with THAT BS again. Screw tubes!).
And you say that you can see the DCT blocking on live video? Not freeze frame, but actual motion going on, with no uncorrected errors in the input stream?
On the other hand, if you freeze a complex image, especially ones with edges abutting flat fields, then I don't expect they're too hard to pick out.
That's the trade off in compression. If you have a lot of action, you need to turn up the compression, which causes more artifacts, but they are hidden by the motion. You can see the artifacts if you stop the motion, but the format wasn't designed for stopped images.
And if the transport layer breaks down, say if you're at the end of a satellite link in a heavy storm, then it's pretty hard to miss the DCT blocks.
I work for these guys and though I won't see a dime if you spend it I've never known a group of people who know more about setting up Audio Equipment. They will take the time to show you what to do, and even set it up for you. This way you don't have to worry about getting scammed.
See, if you're going to invest a few thousand dollars in ANY home system do it right the first time. Call people who know what they are doing, who will come out and offer warranties on what they do, and set it up for you.
But hey this is a shameless plug for a company that I love working for. (Located in Raleigh, NC)
While this loss of resolution sounds disatrous, it's rarely a big deal in reality. This problem only occurs when connecting a 1080i source to a 720p display (and even then, no one but Silicon Optix seems to know how many displays actually use this downconversion shortcut). But when would you connect a 1080i source to a 720p display? Every HD source I've ever used, from over-the-air tuner to satellite receiver to upconverting DVD player to HTPCs, have a selectable output on their side. Select them all to output 720p and you take the processing out of the hands of the display. Problem solved.
Manufacturers better refrain from selling not HD capable displays as HD displays. This is clearly false advertising and there have been several succesful lawsuits lately where people who have been stupid enough and bought into this got their money back.
There's got to be a fairly straightforward formula relating inherent resolution loss when performing any noninteger upsampling, or any downsampling.
Its a bit messy. Imagine 1080i image with a 1-pixel wide sloping black line that is nearly horizontal on a white background. If you throw out half the data, you create an image with a dashed-line. Gaps in the line occur where the slanting line cut across the rows that were discarded. If you upsample from 540 to 720, you will find that the remaining dashes become fattened non-uniformly. In places where the row in the 720-row image falls directly on top of the 540 row image, the line will be thin and dark. In places where the 720-row image falls midway between rows in the 540 row image, the line will be wide and less dark. The end result is the thin black uniform line is converted to a dashed line of varying thickness and darkness -- not pretty.
Even if you resample directly from 1080 to 720, you still run into problems where the 720-row image pixels fall between the 1080-row pixels. At best, you can use higher-order interpolation (e.g. cubic) to try and fit a curve through the original data and try to estimate what was in the middle of the pixels so they can be shifted half way over. But the result wil never look like an image that was taken with a 720-row camera in the first place.
Two wrongs don't make a right, but three lefts do.
When stations, at least in the DC area, broadcast a 720p signal it's considered a big deal. Most broadcast 480p to utilize existing bandwidth for broadcast of two or more stations.
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720p operates at 60 frames (60 full frames) per second. 1080i operates at 60 fields (30 full frames) per second.
If they convert each individual 1080i frame (1920x540) to 720p (1280x720) then they are not tossing any fields (which seems to be the problem). So, if they are converting 1080i@60 fields to 720p@60 frames, then there is no problem here. If, however, they are converting to 720p@30 frames, then they are tossing half the fields from 1080i and we have a problem. All depends on how the conversion is done.
Fly me to the moon Let me sing among those stars Let me see what spring is like On jupiter and mars
If one were to do so, you'd create bad press about your company first, and the industry in general second. That's the fastest way to unemployment.
WTF would prefer the lousy flickering interlaced picture just because of the higher resolution?
It's a big enough shame that this crap has found it's way into the HDTV specs, but WTF does someone use it?!?
If you combine the two 1080i fields into a single 1080p frame, you now have only 30 frames per second. 720p is 60 frames per second. Also, you'll have massive interlacing problems, since the two fields you combined were from different points of time (1/60th second apart) and you're showing them simultaneously.
No, the only proper way to do it is to convert each 1080i field on its own into a 720p frame. It's not really tough, any computer flat panel has the required filtering circuitry inside, and I know my TV does it, thank you. I didn't buy a junky TV.
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This is not particularly news. Some "blogger" discovers something because he never bothered to ask and screams something about the sky is falling.. I'm kind of sick of this "news" reporting. Incidentally, this same issue affects owners of most plasma and LCD tv's with native resolutions below 1920x1080 too.. depending on how you look at it as a problem or not.
Anyway, it's fairly well known that the internal scalers in many devices suck. That is why there is a market for good external scalers. If you are paranoid about watching a lot of 1080i on your 720p projector or LCD TV or Plasma, go buy a scaler. They cost about $1000 but will improve scaled display a lot.
At least if you have an external scaler you will have some options about how you convert 1080i to 720p. The article makes it sound like splitting the fields is a huge sin -- and it is if you discard one field per frame (Half field deinterlacing), but it's perfectly acceptible to scale EACH 540-line field to a seperate 720-line frame and double the framerate. This is called bob deinterlacing and is often the best for converting 1080i video to lower resolutions. If you are watching a 1080i upconvert of a film or something, though, you can have the scaler do full field deinterlacing and inverse telecine for you and see a nice 720p/24fps picture. Scalers also generally have internal audio delays for various types of audio feeds so you won't have to worry about AV sync issues either.
If you have any questions about how your device does this, you should try to find out before you buy it. Most devices don't publish how they do it, though, so your only option may be to derive it -- and that will not be an easy job.
Tell me about it. I got a 46" Sony widescreen rear projection TV, supposedly HD-ready.
It will accept a 720p signal, but DOWNCONVERTS it to 480p for display. This is only noted as a footnote in the user manual.
What use is that? We've been suckered.
--
Marc A. Lepage
Software Developer
As usual when we talk quality, in any discussion it all boils down to: You get what you pay for!
Buy crap equipment and you will get crap.
- To understand recursion, we must first understand recursion -
If you're looking to get into HD there are a *lot* of little quirks to take into account, such as:
- Offically there are two HD resolutions, 720p and 1080i
- Most HD TV's are only capable of *one* of these resolutions. So you have to choose, 720p OR 1080i in most cases. If you want one that can do both, check very carefully.. forget DLP or LCD based devices (fixed set of pixels so fixed resolution), CRT only.
- Many HDTV's will *not* convert from one format to another. They accept only their native resolution.
- Different networks broadcast using one standard or the other. For example CBS uses 1080i and ABC 720p IIRC. Fox is way behind in HDTV support.
- Most HDTV receivers can handle either a 720p or 1080i signal and will convert as required for your TV's native resolution.
- Some TV providers only support one format, regardless of the source material. Ie, in Canada Starchoice only broadcasts in 1080i. Any 720p content they have they upconvert to 1080i before broadcasting. It's impossible to receive a native 720p signal from them.
- The Xbox supports both HDTV modes... but very few HD games actually use 1080i (Dragons Lair being one). Most are 720p. So if this is important to you, you'll possibly want a 720p native TV: most receivers do not have HD inputs that would let you upconvert a 720p game to a 1080i signal for the TV. (the new Xbox will have more HD content than the current one, but it's a good bet that they'll be mostly 720p titles)
- Most Projectors and Plasma's are *not* HDTV. They are EDTV (enhanced definition) or some such. Check the specs carefully.
- Most projectors are 1024x768. This means your HD signal of 1920x1080i or 1920x720p is being heavily rescaled horizontally! Few projectors have a true HD native resolution.
So there you go... lots of fun things to take into account!
Blockwars: free, multiplayer, head to head Tetris like game
"They do not preach that their god will rouse them, a little before the Nuts work loose." Kipling, 'The Sons of Martha'
But if I only bought my HDTV to show off in front of my mates, it wouldn't really matter, would it?
I should also mention that TheaterTek, NVIDIA DVD Decoders, ZoomPlayer, etc. are not limited to SD resolution DVDs - they can play recorded 1080i content encoded in mpeg2 transport or program stream files.
If you have Microsoft's Media Center Edition 2005, you can specify the NVIDIA DVD Decoder (or other competent mpeg2 decoder, such as Elecard's or WinDVD's) for all mpeg2 content including HDTV.
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I work on this stuff, every day.. all day.
only cheap projectors or displays have a maximum res of 720p.
I dont see many of those anyhow.
but yes, on those displays the signal is downconverted by chopping out 1/2 of it.
however, these displays are not popular anyhow.
some of the most popular displays still cant display native, but they are still can display either XGA or SXGA with no proble (were getting pretty close to hd at this point)
dont buy a cheap projector, and you wont get a cheap display. you get what you pay for.
..I'm sitting around wondering why this is a surprise to most people? I thought it was common knowledge that the processing power required to do HDTV the right way was lacking. Even though you're losing some resolution with these displays - it's still digital. That's very important as far as picture quality goes, none of those fuzzy lines to the left and right of menu text. It's also progressive which helps a lot - I can see flicker very easily (If I'm on a CRT with
It's definitely the price you pay for being an early adopter, but I would still argue that the picture you are getting is much better than the NTSC we've been used to for decades.
I went to eat some animal crackers and the box said, "Do not eat if seal is broken." I opened the box and sure enough..
That's not why the Soundblaster Live sucked. Resampling to 48Khz before DAC conversion is the standard way to operate a DAC. The problem was that the resmpler was BROKEN in the Soundblaster Live!-series of cards, resulting in significant, audible distortion in all but 48Khz sound signals. That, and the DAC just wasn't all that good even taking that into consideration. The drivers were awful too.
Ditto. While I am watching the Spurs game on TNTHD on my Sony 50 Inch Grand WEGA LCD Rear Projection HDTV. The element is only WXGA, but the picture is still fantastic. Sure you can get a 1080i CRT or LCD, but for most people it was worth the slight reduction in resolution for the $K reduction in cost.
The results may be one of the following:
You will get a screen full of tiny, shimmering horizontal lines that shift in the center of your screen Congratulations! Your HT gear is showing a true 1080i picture You will get a full screen of gray, possibly with a line in the center Not bad, your gear is properly downscaling the signal Half your screen is black, the other is white Uh oh. Your gear is taking the easy way out and dropping half the scanlines to downconvert (Bele and Lokai) I call that the Cheron Test.Anyone know where to find a list of affected TV's/boxes? Or what to look for when reading specs?
This story is good information and very welcome--it makes up for the Load List Values for Improved Efficiency posting earlier in the day.
org.slashdot.post.SignatureNotFoundException: ewg
I fear for TV. Oh, I think it will survive as an industry, but I am very upset that so much of the act of buying a TV will become just like buying any complex technology. Each buyer will have to navigate a minefield of marketspeak and confusing caveats.
Consider:
You go to buy a new TV. First you have to determine what KIND of TV display technology you should get. You need to determine the size, then you need to determine whether that size will be filled up by a picture and what kind of programs will do that. Then you need to figure out how the TV is compatible with future programming that will be coming soon. Then you need to carefully inspect every logo and claim on both the television itself and the placard announcing its price to determine -- is it _really_ HD or is it something else, 720i/1080i and what KIND (is the 720i throwing away pixels? is the 1080i interpolated 720i?) --, then you need to determine the REAL warranty.
And we're already starting to see the same things in new-fangled TVs that we've in seen in the PC world. Products that break two months after ownership, warranties that are very specific and don't cover parts most likely to break, very inexpensive knock-offs that really shouldn't be in a store, and tweaked marketing claims that have no basis in reality.
Far cry from the days of 13inch b/w TVs.
If Nalgene water bottles are outlawed, only outlaws will have Nalgene water bottles.
No true HDTV enthusiast would ever let their display do all their scaling for them.
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- Not as good as deinterlacing to get 1080p, then resizing that to 720p, but not as bad as the guy makes it sound.
What? You're on crack. With 720p, you have 60 full frames per second. With 1080i, you have 60 fields per second. Why the fuck would you waste the time processing that up to twice the bandwidth, only to bring it right back down again? Take each field, resize it from effectively 540p to 720p, shift every other frame a tiny bit vertically to simulate the interlacing and keep the spatial resolution (this is what 'bobbing' is concerned with).Resizing 1080i fields to 720p frames, to me, sounds like the SMARTEST way to display 1080i content on 720p. The reverse is true as well - take each 720p frame, resize it to 540p, and use those as the fields. Anything more is going to fuck with your image more than it's going to help.
My goodness, there's a lot of idiots out there.
The whiners in TFA mistakenly assume that 2 fields of 1080i = 1 frame of 1080p. This is WRONG, WRONG, WRONG.
It cannot be assumed that the following field has anything to do with the current one. See the "not resized or deinterlaced" picture here:
http://www.100fps.com/
When the television takes the 540 lines in a given field, interpolates the missing lines, and scales to 720 lines, it is DOING THE RIGHT THING. Otherwise your TV would look like the first two example pictures at the above site.
Nathan
I you're displaying sequential frames (that are *supposed* to be offset spatially) one on top of the other, you'll get aliasing as the images "bounce" up and down. On a moving picture this would just look like blurring, but if you could see them a frame at a time, you'd see something like:
| | | | | (frames)
--__--__ (pixels)
(I can't make it line up, but you get the idea...)
I think you'd be better off just dropping odd (or even) fields and upscaling...
Simon.
Physicists get Hadrons!
I wouldn't blame the hardware people for this. They just tried to cheat their way out of the interlacing mess. De-interlacing a picture is damn hard, and probably not worth the effort in this case.
This is exactly what follows from introducing an interlaced HD television standard. The people responsible for this should be blamed.
BTW, here in germany, lots of 'high end' plasma displays are sold that have less than 70% of our SD TV standard's resolution, because they use NTSC panels. They think that people won't notice, and they are right.
Most Plasma and LCD displays are only able to do 720p. They must convert 1080i.
Most tube hdtv are only able to do 1080i. They must convert 720p.
I wonder why they can't do what we have with a computer monitor, the same unit can do multiple different resolutions at different scan rates...
So be aware that if you buy a HDTV, you will have only one "native" resolution. And not all TV will upconvert or downconvert with the same quality.
So if the salesman tells you that it support 720p AND 1080i, go to the manufacturer's web site and verify it because for now only the most expensives displays support both resolution natively.
Try it! Library of Babel
Everyone I know that bought an LCD or Plasma screen has a maximum of 720p resolution. what are you talking about?
---- It puts the lotion on its skin or else it gets the hose again. It does this whenever it's told.
The company saying this is Silicon Optics, who makes the Realta scaler chip (featured in the $3,500 Denon 5910 DVD player), and is obviously trying to get people to use their chip, or buy a scaler based on their chip. Now, from the reviews I've read of the 5910, it's the best reasonably priced (under $10k) scaler on the market. It's amazing. However, when they say "Almost all other companies throw away this extra data and do it the lazy way" without naming the companies, I believe them as much as I believe those recent Apple benchmarks.
I'm almost sure their scaler will help with most sources you feed your 720p HDTV, what it can do with 480i DVD's is impressive enough that you would believe that. However, I doubt the problem is as bad as they say it is. Also, 1080p DLP sets are going to start hitting the market soon, and in a couple of years 720p will probably have been pushed out of the market mostly. Given what a scaler costs, I'd probably save my money to get the 1080p set in a couple years since the 720p sets still look great.
I have a 1080i set, but I considered a 720p DLP set since they looked amazing and only didn't because of cost.
When it's £7.20.
I'd certainly agree that people should do research before diving into HDTV. However, there's a ton of misinformation in the parent post.
- The HDTV spec includes three resolution,s not two: 1080p in addition to 720p and 1080i. Few devices support 1080p today, but a bunch will appear around the end of this year.
- Any modern HDTV will support both 720p and 1080i. There may be scaling going on (and the quality of that scaling is the point of the original article), but any modern device will happily display both.
- DLP and LCD devices can certainly do scaling as well as anything else. CRT's are the only devices that can switch their native resolution, but with the proper signal DLP, LCD, and LCOS are all fine with 720p and 1080i.
- I have never seen an HDTV device that accepts only its native resolution. At the very least, they've always accepted 480i (NTSC) and 480p (progressive scan DVD's) in addition to their native resolution. I haven't seen a device manufactured in the past three years that couldn't accept all current HDTV resolutions (that is, everything except 1080p).
- Fox is not "way behind" in HDTV support: last season, they broadcast 6 or 7 HDTV football games a week. CBS did 2 HDTV gaames and the rest in SD.
- Most XBox games don't even support 720p. And again, native resolution is meaningless with a decent scaler, which more and more devices have built into them today.
- "Most" projectors that are intended for home theater use are indeed HDTV capable today, though many of the cheaper ones (http://www.projectorcentral.com/ , http://www.avsforum.com/ , and good old Google.
Cheers
-b
If I wanted a sig I would have filled in that stupid box.
You can usually go into your cable/sat box and tell it what to output. If you de-select 1080i as an output format it will do the converting to 720p instead of the TV which should give better results. It's amazing how many times I've seen the cable guy screw up HD installs. They'll have the tv and the cable box stretching the picture which cuts off the edges.
If you're a real quality nut like me then get a tube based HDTV, they can actually get close to doing 1080i.
What if Digg added local news and a Slashdot inspired comment karma system? ---
http://houndwire.com
So I'm back to having my DVD watching held hostage to Microsoft and Windows crashes/glitches again? NOOOOO Thanks!
Well, that's why I'd build a Linux dedicated HTPC or just get a Mac MINI and the exteranl 7.1 sound decoder. I'm in the process of doing just that.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
Yep, I have the same thing. The reason, I believe, is because even dropping down to 540p before upscaling to 720p leaves you a LOT more information than standard NTSC. First of all, NTSC is 480i, not 480p---so really it's reasolution is somewhere between 240p-480p due to the losses incurred by interlacing. And secondly, 1080i content has only 540 lines of chroma resolution anyway; you're really only losing luminance information. (Not to minimize that---luminance is the most important component---it's just that we're losing less that you might initially think.)
If you've ever seen high-def on a 480p EDTV plasma, you'll understand just how superior the picture STILL is compared to 480i NTSC.
Nevertheless, true 1080p deinterlacing is coming down the pike right now. Faroudja, SiliconOptix, and Gennum have all created solutions, and we should begin seeing them in external video processors and displays soon.
Did anyone notice that, despite the accusation, Silicon Optix calls out NONE of their competitors for this supposed "issue"?
Gennum, Pixelworks, Genesis, Oplus (now Intel), and several others make their own scaler/deinterlacer chips. Most of these have already found their way into displays and have proper deinterlacing strategies in them. Nobody scales without deinterlacing first anyway in a modern image processor.
Silicon Optix's technology is based on offline film processors by Teranex. While they can certainly be high quality, they aren't the top of the heap either by volume or by prestige. Genesis/Faroudja had a name for a long time with their "line doublers" which are over 20 years old and their more advanced but cheap gm1601 is one of the more popular solutions for HDTVs. Gennum's GF9350 with VXP technology is currently in the largest plasma tv in the world (Samsung 80"). These and other scaler/deinterlacer chips have none of the problems that Silicon Optix claims exist. If you look at the debates that rage over at the usual enthusiast sites, you'll see that there are issues with its own technology like latency and cost that aren't present in the other solutions I mentioned.
Just like Silicon Optix's "odd film cadence technology" which requires nothing different than what everyone else has today, this reeks of a cheap PR vehicle. While the choice of scaler and deinterlacer is important, it is not the utter tragedy that SO would like to make it out nor are they the saviors of the HDTV world. If they know who the culprits are, then let them name whose image processor it is that creates these problems.
Something of significance to know is that Faroudja makes very affordable very high quality scalers that will upscale and downscale to/from 1080i quite well using the full 1080i picture (that is, two frames since it has that i thing happening). Hardware scalers work really well. Really.
Infact, with most scalers you will still notice that 1080i has more source pixels than 720p.
Also, there are some people out there that make native resolution 1080i/p displays. Kudos to those peeps.
...for letting companies dictate ATSC instead of a government standards body. 18 formats, crappy MPEG2 bitrate, and a shitty broadcast/antenna situation instead of 1 reasonable standard.
I haven't RTFA, but I do have a DLP projector (Infocus X1) which I love. For me it's relative. I liked CDs and CD players when they first came out because they were much handier than cassettes and records, and I like DVD much better than VHS, and I love my projector because it's a thousand times better than my old 19-inch television screen.
So I don't care what it can't do. What it _can_ do is terrific!
Ignorance in this topic apparently _is_ bliss.
Oh, this was going to be great. Fidelity like you never had it before. No scratches. No groove wear. Dynamic range you won't believe. Crystal clear highs. Thunderous lows, with no rumbling feedback even if sat your player on your speaker.
Remember the little logos? AAD? ADD? DDD was the best you could have (digital recording, digital mastering, and (obviously) digital media in your hand). And a lot of hard work on the part of the engineers operating the mixing boards. It's that last part that costs time and money. Now, all the equipment is digital. So, it's all great, right? Sorry--the technology is not the limiting factor in sound quality anymore.
The limiting factor is apathy. Most people can not really hear the difference. And fewer people care.
Exactly the same thing is now happening in video.
Since we can't improve the functionality (well, we could, but you'd never notice). It's pure hype from here on out.
Now, where'd I leave that case of speaker spikes and green markers? Gotta get 'em up on ebay; David Hannum was right.
"Reality is that which, when you stop believing in it, it doesn't go away." - Philip K. Dick
As long as they list the RMS per channel I don't care how they describe the peak power.
I can see where it would be misleading to those that didn't know.
I believe my system is 550W meaning 100W peak * 5 channels + 50W peak Subwoofer. I'm okay with that because on the original box it also listed the RMS for everything.
550W is not wrong, it's just peak and no one listens to their system at peak anyway.
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
http://www.pcmag.com/article2/0,4149,1429898,00.as p
It was made by Sharp of all people. It was a nice picture too. I'm not sure that anything is broadcast in 1080p though. This was about 3 months ago so others might have the ability by now.
I told myself I would probably wait until content was available in 1080p before making the plunge. Of course, by then some higher def standard will be on the horizon.
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
perhaps your projector is properly combining the 2 1080i fields and downsampling as opposed to discarding half.
. But many displays do this by discarding half of the 1080i HD signal, effectively giving 720p viewers an SD signal - not watching HD at all! "
Interlaced material is temporally displaced, not just spacially.
If you want to "deinterlace" the material without losing data, you'd want to display each field of the 1080i back to back, which is precisely what their projector does (although 540->720 conversion is problematic).
You'd also need double the fps to pull it off.
- Michael T. Babcock (Yes, I blog)
nobody will notice or care.
"How to Do Nothing," kids activities, back in print!
Most settop boxes support (most actually require) choosing one output resolution to display at. So, if you have a 720p display, you tell it to output at 720p.
Then, when the box is decoding the MPEG2 HD data, it does the 1080i->720p conversion, providing a pretty good output result.
My "MyHD MDP-130" PCI card has a nice HD decoder chip which does an excellent job of converting 1080i to 720p for output. It also does a nice job upscaling DVD content to 720p. My parents' HD Tivo also does a nice job of converting 1080i material to 720p for display on their DLP TV. I think pretty much any recent HD display chip will do a pretty good job of conversion between the various HD standard formats.
I'm sure all of the other /.'ers have heard of resampling before. The real only way of getting a good hd or other high quality signal to be displayed is to match the media to the display device and this is tricky business. We now have all of the issues of 4:3 , 16:9 and the other ODD screen ratios in addition the the resolution of the signal especially in computers.
My suggestion to home theatre people is to buy a GREAT scaler of their own. This way you can pass it 480, 720, 1080i, VGA etc signals and convert it via line doubling and other techniques to get the image to match the max resolution your projector can handle. Spend $1000-$2500 on this then go get a decent projector! Projector scalers are average at best until you hit the $20,000 projectors.
Kudos!
I have seen pros and cons on how these sets do their sampling. Here is my advice -- go look at the picture on a set with a good HDTV source. Use the specs as a guide but don't trust them. Get what looks good to you. My father would never have been able to see anything more than the quality of a good DVD. He couldn't see the difference between crappy digital cable and DVD. Some people like me are so manic about visual quality we will devote huge amounts of time tweaking our systems. While my system is probably limited to about 1500 lines of resolutions due to the lenses, I find its image much warmer, uniform, and pleasing to the eye than the pixilated look of some very high-end flat screen solutions that go for 10-20k.
About the only thing that really shows how good HDTV can be is material that is shot originally with HDTV video cameras. Upconverting film inevitably introduces a softness that is exaggerated by systems like mine. For now you can only see a few things on the Discovery Channel and a few musical events in true HD (meaning not upcoverted from film). I mention this because while I advise you to go see for yourself (if possible) most stores don't really offer a good enough HD signal to display the difference. If you can hold out a little longer I would wait until either HD-DVD or Blu-Ray players hit the shelves and then demand a demo with these HD sources to make a decision.
One final note, I haven't noticed that 1080i hasn't had as much comb-artifact during motion as I would have expected, but there still is a noticeable blurring during camera pans (maybe this is just combing in disguise). I'm sure I will get a little boast in quality when I can play off of a true 1080p source. If I were to design the next generation of video recorders I would introduce variable framing rates in playback. The picture being refreshed as high as120fps, but the actual picture updates depending on need for frames to eliminate motion blur. About motion blur, storing 120fps would be inefficient and overkill. The system I propose would make true frames at like 30-60fps, but as the camera moves, the edges would be scrolled in as needed to keep a smooth fluid motion. A really intelligent system might be able to also track one or two moving objects across this field and give them higher frame rates as well. At 2 mega pixels, I think we need to retrench and try to slay motion blur before going onto higher pixel counts.
Letter To Iran
a lot of smart people talk about motion blur in conversion of interlaced to progressive video. however, the assumption many people make is that the recording was done interlaced. try thinking outside the box for a second people! if the recording was done progressive, (then maybe broadcast interlaced, recorded interlaced and played back progressive), then there's no motion blur!!! so as long as the original capture is being done 1080p (think AVC mpeg4 video), the conversion to 720p will not result in motion blur. hopefully, high end commercial cameras can do 1080p (even if there is no such thing as 1080p hdtvs) for just this reason.
if you don't understand this, and you think i'm wrong, then you're stupid and i just give up.
Back in the day, on the Atari and Amiga, you could actually do stuff in that interrupt time. The most common thing was to swap display buffers for double buffering. This made for rock steady hardware scrolling, an effect that still lacks somewhat in today's PC's, believe it or not, as there was absolutely no tearing of the display whatsover. Just a beautiful effect.
This is my sig.
I have a Mits 52725 (based on the HD2+ DLP chip) and a Dish 811. What I have noticed is that setting the Dish 811 to output at 720P (the Mits "native" vertical resolution) the display is of significantly lower quality (including "jaggies") than setting the Dish 811 to output in 1080i and letting the Mits handle the scaling back to 720p. I am not sure if this is because the Mits does proper scan converstion or due to some unreleated quality difference between the Mits and the Dish 811. What I can tell you is that when the OTA/Cable(QAM) stuff comes in at 720P (the Mits shows the format for the tuner-based stuff) it looks as good as the Dish 1080i, and vise-verse. I recall reading that the Mits had Faroujda, but I am not sure where I read this.
But if you are converting from 1080i to 720p, yuu don't have any other choice, do you?
The full names for these are 1080i60 and 720p60. That means that you are getting an interlaced 1080i field (which is 540 lines) 60 times per second. Since 720p60 gets a full 720 lines 60 times per second, you have to take the half of the 1080 that you have in that 60th of a second and scale it up to 720 then you have to do the same again for the other field.
It would be different for 1080p, but there are very few (if any) 1080p60 sources.
So, your 1 pixel line would not turn into a jagged line, it would just be there half the time and show interlace artifacts just like any 1-pixel line in an interlaced signal.
A lot of RPTV Microdisplays (and other systems including CRT direct-view TVs) have profound overscan- where some sections of the full, native resolution is lost in the edges of the TV. This means that pixel 0,0 (for sake of example, upper left) might not be visible and the first visible pixel may be 10,10. This can be adjusted (electronically or phyiscally) on some, but not all, displays. In these situations, 720 (or even 1080, depending on the device) isn't visible...
i have my projector (Sanyo Z2) set to 720p (not auto) to see if my Comcast HD cablebox sent out 720, and it does.
I tried sending 1080i, and (after changing the projector to 'auto' input) letting the Projector 'downscale' it, and it looked 95% as good (had to look for stuff and still couldn't find differences on some source material)
Yet...
I tried setting the cable box at 480p and letting the projector upscale, and didn't look as hot (I'm 114" from a 96" screen) -you could see the source material pixels at times, or artifacts from them.
If i send my DVD signal at 480p and let the projector upscale to 720p, not bad. But my DVD has a built-in upscaler (momitsu) that is nice, and having it send things at 720 down the component cables (or dvi) is better.
So, i'd say that Comcast in VA on the Scietific Atlanta 3250HD box isn't doing this "1080 / 2 then upscaling" trick, b/c the "720p" picture on my HD cable looks a lot better than either method of me feeding 480p and upscaling (and the projector has a highly rated upscaling chip)
my projector is 1280x720 native: http://www.projectorcentral.com/Sanyo-PLV-Z2.htm
If she floats, she's a witch.
Your 1080i stream is just a sized-up 720p stream. BOOOOOOOOOOO! Most people can't tell, though.
My DLP monitor's native resolution is 720p. Before purchasing the unit, I read up about signal, conversion, interlacing, etc. The conclusion I reached is that my monitor should do one thing and do it well. That one thing is to display a picture at its native resolution.
Almost everything I've read notes that the deinterlacing hardware in most TV's flat out sucks. My solution? I bought a Samsung DLP sans ATSC tuner. My TV is a display, nothing more. Had I been able to, I would have purchased it without the NTSC tuner as well. Buying the tuner separately affords me the opportunity to buy a better quality piece of hardware without the redundancy of having purchased the same hardware in my monitor.
I'll deliver a quality 720p signal to my monitor, and it will display the picture. What's more to ask?
"When I get around to buying a HD television (not any time soon, I do all my televisioning on my computer), it will be a true 1080i (are there 1080p televisions?) display so I'll know I'm getting the full potential of HD."
why do you think all of the 'source' material at the hi-end AV stores that's showing on 'real' 1080i displays are "nature" videos showing ducks flying/migrating gracefully over marshes? Nice and smooth, graceful... (blah)
B/C sports and action look better at 720p. I compared side by side before buying my 720p display device (which happened to be a projector...)
If she floats, she's a witch.
This entire thread is silly. I have great projector, native 1280x720 pixels. Every Hi-Def device I own lets me specify the output resolution. I run them all at my projector's native resolution.
Nearly all HD content is movies (progressive scan), or HD-original content (actually videotaped at 1080p, a better-than-standard format), very little content is actually interlaced. The reason is, compression codecs are more efficient at non-interlaced frames, and directors/producers know that a non-interlaced master will more easily transfer to film for theater release. Not to mention that the highest quailty television shows are actually filmed, then transferred to video.
So all this content gets compressed as non-interlaced frames. Real HDTV broadcasters have to pick a signal standard for transmission, which is MPEG2, 720p or 1080i, but the cable/satellite guys use MPEG4 at whatever resolution they feel like. The entire discussion is moot because most of the content never sees an interlaced format until your living room, where only an idiot would overdrive their projector's native resolution.
I *can* see the difference between SD and HD, and I'll tell you that with my projector (panasonic PT-AE700U) and Voom and DirecTV, 1080i and 720p can look equally stunning, depending of the quality of the content. Maybe if filmmakers started using larger stock, or digital movie cameras, their films would look as good as Jay Leno.
I disagree and will attempt to clarify my points below.
- Any modern HDTV will support both 720p and 1080i. There may be scaling going on (and the quality of that scaling is the point of the original article), but any modern device will happily display both.
My point was what the TV was capable of displaying *natively* without any rescaling... the point of the original artical as you say. Additionally I think you'll find that there are many TV's that do *not* support both formats through rescaling or natively. I purchased my HDTV less than a year a go and it, along with virtually all the TV's I looked at, didn't support one or the other standard at all. If I apply a 720p signal I get a scrambled screen.
Does this apply to all TV's? Certainly not, but it does to many and is something to consider when purchasing.
- DLP and LCD devices can certainly do scaling as well as anything else. CRT's are the only devices that can switch their native resolution, but with the proper signal DLP, LCD, and LCOS are all fine with 720p and 1080i.
Again, my point was in regards to native resolutions and avoiding rescaling. That your purchase is usually a tradeoff on which resolution you want to natively support. It's impossibly to get anything other than a CRT based system to handle both resolutions natively.
- I have never seen an HDTV device that accepts only its native resolution. At the very least, they've always accepted 480i (NTSC) and 480p (progressive scan DVD's) in addition to their native resolution. I haven't seen a device manufactured in the past three years that couldn't accept all current HDTV resolutions (that is, everything except 1080p).
Look again.. as I mentioned most of the TV's as of less than a year ago couldn't support both 720p and 1080i. You're right regarding the 480 based resolutions, I wasn't including those... I was only talking in terms of HD.
- Fox is not "way behind" in HDTV support: last season, they broadcast 6 or 7 HDTV football games a week. CBS did 2 HDTV gaames and the rest in SD.
They're catching up, but you mention Football. How many of their regular programming outside of sports is HD? Though I haven't looked lately, so it's possible the number is significantly higher than when I last looked. They were much later in adopting it than the other broadcasters.
- Most XBox games don't even support 720p. And again, native resolution is meaningless with a decent scaler, which more and more devices have built into them today.
True, not my point. THe next XBox games will all be HD (or so the rumor goes). Yet it will likey be 720p, so that's an issue. Rescaler again, IF the TV supports it and IF you don't mind the image being rescaled.
- "Most" projectors that are intended for home theater use are indeed HDTV capable today, though many of the cheaper ones (http://www.projectorcentral.com/ , http://www.avsforum.com/ , and good old Google.
No, most are capable of taking an HD signal that will get resized to the native resolution of the projector - usually 1024x768. Again a question of native vs rescaled.
Not trying to nitpic, but my main point was that you'll likely need a rescaler in a lot of places, and that your TV does not necessarily include one. If you want the best picture, pick the native resolution you'll use most. And to research and double check exactly what your proposed TV supports, they aren't always clear.
http://www.hdtvarcade.com/xboxlist.htm ~M
>> How on earth am I going to know if it's the set or the signal that's producing all those jaggies?
Bring your DVHS or HDTV PVR or Myth box on which you have high-def content. Plug it into each monitor in your price range and compare. Buy the one you like the best. Seriously.
Would you buy a car if you were only allowed to ride along with the salesman driving only on specially prepared roads? no way. Or how about a stereo system without being able to pop in your own music or adjust the volume? Again, no way. Then why should you spend thousands of $$s on a monitor that may or may not do what you want? It's about the machine's ability to reproduce the content you desire. If the store doesn't have the content, bring your own and put the device through its paces.
And if the shop won't let you unplug the store cables and connect your equipment, then take your money elsewhere to a shop that actually values your business. You might pay a bit more than you would at the big box stores, but that's life. If you really care about what you're buying, take your business and your money elsewhere and let them sell low-quality crap to the masses.
If you try to de-interlace the two 540p frames to generate a 1080p frame before scaling down, you end up with 720p at 30 fps, because you have to wait for two cycles to get the next 1080p frame.
This would introduce intolerable flicker for most videophiles.
The other option to generate 1080p frames would be to have rolling frames where a new 1080p frame would be generated each 1/60th of a second using the two most recent frames. This technique would result in its own set of video artifacts. Two examples would be when something is moving quickly across the screen, or when there is a fast cut-scene. In the first situation, the object would be blurred (probably even more than by the current technique), and in the second the scenes would be blended. These types of artifacts are ones that reviewers can test for and downgrade for, so it's not surprising manufacturers opt away from this solution.
There's a good chance that this "cheap" solution is just the best choice from a bad lot. While it may slightly degrade the image overall in a way that's visible to videophiles, it lowers any risk of really bad artifacts that the average consumer can see.
We are the 198 proof..
I said, "There are 18 recognized MPEG stream formats for HDTV." That should have read "for digital TV" not "for HDTV." Only the last six of the 18 modes I listed are HDTV. The others are SDTV, or, arguably, EDTV.
www.wavefront-av.com
"I have a 720p projector paired with a 110" screen. Both 720p and 1080i material look fantastic. Maybe the supposed degredation would be visible side-by-side with a native resolution projector, but I certainly wouldn't worry about it based on what I've been watching."
I have a similar rig, although I'm only throwing to around 90". I am probably totally incorrect, but I think these sorts of issues may be more visible on plasma and LCD displays than with projectors, the cinematic properties of which tend to reduce some of the aliasing and jaggie issues I've seen with plasma and LCD.
I believe this is one reason why some home theatre experts opine that plasma screens are great if you want a really cool-looking TV to go with your cool-looking furniture, but if you're actually serious about watching movies in your home, get a projector and a screen.
Sitting in my day care, the art is decopainted.
Addison-Wesley had published the ROM code, and I think maybe the OS code? How many hours did I spend drifting through the source listing to see how it was all architected...
Though the Unix source was available to schools, I was unable to get a copy at the time, and, well DOS was being reverse-engineered in pieces in books and mags. It was the first big OS I could start to understand (Atari 400/800 also published their rom listings IIRC).
Once you learn the audio artifacts from any audio compression, its hard to listen to lossy compression unless its at a pretty high sample rate; at least 256-320bps.
That's why I always tell people who are satisfied with 128kbs AAC's to just keep listening and be happy. Once you know where to listen, you inevitably do and you hate anything compressed that way. Its kind of like when you have a dental problem and your tongue keeps "finding" that spot on your teeth.
When is 720p not 720p? well according to wikipedia:
One pound is divided into 100 pence, the singular of which is "penny". The symbol for the penny is "p".
Prior to decimalisation in 1971, each pound was divided into 240 pence - although it was usually expressed as being divided into twenty shillings, with each shilling equal to twelve pence. The symbol for the shilling was "/" or "s" - not from the first letter of the word, but rather from the Latin word solidus. The symbol for the penny was "d", from the Latin word denarius. (The solidus and denarius were Roman coins.)
After Decimal Day, the value of one penny was therefore different from its pre-decimalisation value. For the first few years after 1971, the new type of penny was commonly referred to as a "new penny". Coins for denominations of ½p, 1p, 2p, 5p, 10p and 50p all bore the name "NEW PENCE" until 1982, when the inscription changed to "ONE PENNY", "TWO PENCE", "FIVE PENCE" and so on, also, the half penny was removed from circulation.
We always knew Comcast was corrupt, here's the proof: http://tech.slashdot.org/comments.pl?sid=1909890&cid=34545432
Who said HDTV was going to be too complicated?!? And I was afraid it was going to be a hard sell to convince my Mom what the right technology, model, resolution, etc. would be for her transition into the world of HD TV.... Now that I've RTFA, and read as many posts as possible I see this is going to be a really easy task. To save myself a little time, hope y'all don't mind, I've just e-mailed her the link to this story on /.. I'll let her figure it out.
This should be required reading for anyone about to buy a TV.
http://answers.google.com/answers/threadview?id=47 089
One of the more interesting insights is that the coroprations don't want to publish the exact specifications of their HDTV systems because it might impact their Plasma screen sales if customers found out they only get 1/2 of HDTV on their brand new $9,000 screen.
Here in Europe the primary resolution for normal digital broadcast is 720x576, 25Hz (or 50Hz interlaced). 704*576 and 768*576 seems to be common as well.
And that's just the standard resolution digital content.
.... Because there's a story out today that says that 50% of Canadians who have an HD TV don't have a set-top box to actually get HD. 16% of those don't even realize they need one.
Bizarre....
This is my opinion. To make sure you don't steal it, it's covered by the DMCA.
Well that's why I'm going with a Mac mini for the HTPC, since I can just put in a disc and have it start playing just like a DVD player should.
I have no desire to make an HTPC complcated, believe me. I just want to watch TV, a DVD, or some other recorded video. But why is it not better to strive to get rid of multiple boxes and replace them with one?
"There is more worth loving than we have strength to love." - Brian Jay Stanley
Would it convert the 1080i60 to 720p60 or to 720p30? If you convert to 720p60, you're going to end up with a jittery picture (you could adjust the scaling by a half-scanline, but edges would still seem jittery). From the description of "throwing one field away", it sounds like it's downsampling to 720p30, and it would provide the most consistent viewing experience (equally good or bad at rendering every 1080i60 stream).
I used up all my sick days, so I'm calling in dead.
Comment removed based on user account deletion
FOX: 720p native
ABC: 720p native
CBS: 720p native
NBC: 1080i native
Would it convert the 1080i60 to 720p60 or to 720p30?
How about a weighted average of bob (1080i60 to 720p60) and weave (1080i60 to 720p30) interlacing?
Does the "blocking" come from the DCT? Or from low quantization?
The "blocking" is image discontinuities at DCT block edges, which tend to pop up when you run heavily quantized data through an inverse DCT. Every transform will have its own characteristic flavor of noise. DCT is an older transform compared to the newer MDCT (DCT with overlapping blocks, used commonly in audio codecs) and wavelet transforms, which hide the noise better.
Now why would digital cable and satellite providers heavily quantize data?
Now, someone commented that CRT's are dead. Not if you have a budget, they're not! I've owned an HD set for over three years now, and it only ran me $700. It is a CRT. It has a beautiful picture.
Even today, it's very hard to match the picture quality of a modestly priced HD CRT. To my eye, only the very top end LCD displays, costing in the thousands, come close. CRT based HD displays are now well within the price range of the "average" TV viewer, and the improvement in quality over standard TV is dramatic.
Just checked out the Sanyo (thanks for the link) and more importantly the Momitsu... the V880N is amazing, and I love that they readily support firmware revisions (one of the reasons I love my Samsung NUON based DVD player.
Anyway, thanks for the 411.
"The more pity, that fools may not speak wisely what wise men do foolishly" - Touchstone,Shakespeare's "As You Like It"
But just as he got home he figured out it was a mule after all.
The artical assumes 1080i to 1080p conversion is a lossless process. It is not always straightforward. 1080i from non-progressive sources has iterlacing which is clearly noticeable when directly converted to progressive by merging odd and even lines. It makes more sense to drop the odd or even lines when converting to 720p than bothering to de-interlace using some image processing techniques. Any de-interlacing technique softens the image and in my experience is worse of than reducing the vertical resolution by half.
images destinted for interlaced display have to have there vertical resolution reduced anyway before display since there would be unacceptable flicker otherwise. This is the reason for the flicker filter on the ntsc/pal output on PC vga cards, it is also why no dvd titles I am aware of can offer the full vertical resolution the format is capable of as there is too much flicker when on an interlaced tv. I recall a figure of 3/4 from somewhere, so your 1080 line display can only provide a stable image containing about 800 lines anyway. If they were sensible when developing HDTV they would have only provided for 1080p 24 or 30 FPS modes, but the tube was still king back then so interlacing it was. Interlacing was a kludge when it was invented, and should _never_ have being adopted in a 1990s standard. It is possible to accuratly de-interlace things that were originaly progressive before interlacing (With the drop in vertical resolution noted above) but anything sourced from interlaced video can never be made progressive with out some form of artifacts. People in NTSCland dont see it often, but in PAL countries its very common for TVs to offer a 100Hz mode that deinterlaces and frame doubles the video to remove annoying 50Hz flicker, and all to often on these TVs there are artifacts on moving video like football or news footage.
This has to do with signal bandwidth. Since 720p is progressive and 1080i is interlaced, 1080i has 540 lines as compared to 720 lines in 720p. 540 video lines is much easier on the tubes and result in a sharper picture then 720 lines, becouse the tubes of most crt projectors are strugling at such high values.
n1080P me like.
.pa Sweden [GMT +01:00]
Look, all a computer does is coalese a few different types of media - CD's, DVD's, and other more temporal media. All of the other components we know and love like amps are still there.
It also opens up the possibility for new types of components that are actually pretty exciting since it brings new abilities into the home - like slideshows on the home theater, where they are meant to be in the end.
Components are already computers, so it does no good to say it's bad to see some computers looking more like components.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
Decent inexpensive conversion between 720p and 1080i can be done, without downrezzing to SDTV by ending up with just 540 lines of vertical resolution.
The secret is to process the even 1080i fields differently from the odd 1080i fields, choosing different lines to blend or interpolate or double or drop. Sophisticated de-interlacing of 1080i to 1080p first will help but is not necessary.
If the processing does not de-interlace the 1080i first and also treats the odd and even fields the (exact) same way, the resolution will be cut to 540 lines vertically.
More:
http://members.aol.com/ajaynejr/hdconv.htm