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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! "

85 of 399 comments (clear)

  1. Reminds me of Sound Blaster by Anonymous Coward · · Score: 4, Insightful

    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.

    1. Re:Reminds me of Sound Blaster by Shkuey · · Score: 5, Informative

      Actually this is an issue of giving people what they want. In this case an HDTV that isn't a thousand bucks more expensive and doesn't have a video processing delay.

      The first incorrect thing in the /. post is that this is somehow standard definition. It's not, 540 lines is more than 480. Not only that but they process 1920 lines of horizontal resolution (scaled down to 1280 for a 720p display), which is quite a bit more than 640.

      Anyone who is serious about getting the absolute most out of their display will have an external scaler and a device to delay the audio. Frankly as digital display technologies take more of a foothold in the market I'm hoping these interlaced resolutions will become far less common.

      When I first read the headlines I thought they would perhaps talk about 1024x768 plasmas with rectangular pixels being marketed as 720p. That kind of thing is far more blasphemous in my opinion.

      So in summary of TFA: 720p is not 720p when it's 1080i.

    2. Re:Reminds me of Sound Blaster by GutBomb · · Score: 3, Informative

      the government mandate is for DIGITAL broadcast. it has nothing to do with HDTV. there are digital over the air broadcasts of SD content as well, and the government mandate says that all TVs made after January 2006 must be capable of recieving Digital ATSC over air signals, and that all over the air broadcast networks start broadcasting digital ATSC signals.

    3. Re:Reminds me of Sound Blaster by Pope · · Score: 3, Insightful

      Wow, do you have it backwards! The FCC wanted a single HDTV/digital standard, and it was the industry that pissed and moaned and dragged their feet as to what standards to support. Now you have half the broadcasters on 1080i, and half on 720p, and massive confusion in the marketplace.

      This is one place where ONE standard would be fine. Remember good ol' NTSC? Single friggin' standard, and all TVs sold here support it with little to no problem.

      The government (FCC) had a job to do, and it failed its citizens miserably, by knuckling under to the corporate interests you seem so keen on defending. Not everything can be solved with a free-for-all market battle, and certainly nothing as big as broadcast television should be. It's all a very nice theory you have, but is not practical by any stretch of the imagination.

      --
      It doesn't mean much now, it's built for the future.
    4. Re:Reminds me of Sound Blaster by steve6534 · · Score: 4, Informative

      :The NTSC video standard has 525 lines. :The PAL and SECAM video standards have 625 lines. :So where does 480 linrd come from? The specification is for 525 lines but there are only 480 lines of picture informtation - The other 45 are blank lines that were designed to let the electron gun get back to the top of the screen to begin drawing the next frame.

    5. Re:Reminds me of Sound Blaster by Shkuey · · Score: 2, Informative

      Televisions are not computer monitors.
      The NTSC video standard has 525 lines.
      The PAL and SECAM video standards have 625 lines.
      So where does 480 linrd come from?


      480 lines are actually shown on a typically television. The remains of the signal are overscanned and not shown. Though many displays slightly overscan an HD signal, this can be also be filed under the blasphemy that is 720p not being 720p, and there is no technical reason it needs to be done.

    6. Re:Reminds me of Sound Blaster by J+Isaksson · · Score: 5, Informative

      Due to interlacing, a single 525 line picture is split into two ~262 line frames for display on the TV screen.

      Lines 243-262 of each frame (off the bottom of the TV) start with 0.3V for 4.7us, and the rest is 0V. This tells the TV to prepare for a new frame.

      This leaves just 242*2=484 lines of effective display.

      http://eyetap.org/ece385/lab5.htm

    7. Re:Reminds me of Sound Blaster by uncoveror · · Score: 3, Insightful

      The government staying out of the equation, and letting the market decide did a wonderful job with AM stereo and quadraphonic records. Someone must set standards, and only the FCC, and other such agencies internationally have the authority to do so. Could you imagine haw color TV would have caught on if there had been a format war instead of NTSC? We all need to stop bowin beforew a golden calf called the "free market".

      --
      The Uncoveror: It's the real news.
    8. Re:Reminds me of Sound Blaster by ePhil_One · · Score: 2, Insightful
      1024x1024 plasmas? That is weird, whats the brand?

      But getting back to the subject, this article is goofy from the start. It supposes that the "proper" way to down convert the 1080i signal is to first convert it to 1080p, then down convert it; mostly because thats the way the "geniuses" at HQV have done it. But if you think about it, thats a brain dead solution too. Why?

      The 1080i signal is 2 540 line scenes, shot 1/60th of a second apart, with half the picture data. If anything on the screen is moving, it will be in a different place 1/60th of a second later. if you mash those two scenes together into a 1080 line image, those items in motion will blur without some complex 3-d (time being the 3rd D) reconstruction. If you instead treat the 1080i signal as a 540p signal, you eliminate the motion blur at the potential cost of some static image sharpness.

      In other words, pick your poison. The blog has shown itself to be either an advertising shill or lacking in technical competence since it completely failed to go into the real issues here...

      --
      You are in a maze of twisted little posts, all alike.
  2. It's there by Anonymous Coward · · Score: 5, Funny

    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.

    1. Re:It's there by ergo98 · · Score: 2, Insightful

      The HD signal's still there...

      Especially given that 540p is still HD. 540p is a hell of lot better looking that 480i. In fact 540p is one of the HD standard resolutions.

  3. For the inevitable /.ing by Anonymous Coward · · Score: 5, Informative

    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/

    1. Re:For the inevitable /.ing by Overzeetop · · Score: 4, Informative

      That's all well and good, but I'm afraid I tend to agree with them. If content providers want to "do it right" they should ditch the 1950's interlacing and get with the 1980s.

      He's leaving one step out. 1080i is 540 lines scanned 60 times per second, offset by half a vertical pitch. 720p is 720 lines scanned at 30 times persecond.

      To try and take two frames which are not occuring at the same instant, stitch them together, remove the motion artifacts, resample, and then display is just plain silly. And frought with errors, as you are expecting a computer to determine which parts of the motion (over 1/60 of a second) to keep and which to throw away.

      If you wanted high fidelity, you'd spend the money for a 1080p60 system. Then it wouldn't matter. Except that you would complain about the quality, because each frame you see was upsampled from only 540 lines of resolution.

      It all comes back to the fact the the FCC let the industry choose this "18 formats is good" spec.

      Personally, I'm in favor of an olympic standard mayonaise, but...no...wait...awww hell, I give up.

      --
      Is it just my observation, or are there way too many stupid people in the world?
    2. Re:For the inevitable /.ing by Phreakiture · · Score: 5, Informative

      720p is 720 lines scanned at 30 times persecond.

      Mostly incorrect.

      There are 18 recognized MPEG stream formats for HDTV.

      • 640x480 24 fps progressive narrow
      • 640x480 30 fps progressive narrow
      • 640x480 30 fps interlaced narrow
      • 640x480 60 fps progressive narrow
      • 704x480 24 fps progressive narrow
      • 704x480 30 fps progressive narrow
      • 704x480 30 fps interlaced narrow
      • 704x480 60 fps progressive narrow
      • 704x480 24 fps progressive wide
      • 704x480 30 fps progressive wide
      • 704x480 30 fps interlaced wide
      • 704x480 60 fps progressive wide
      • 1280x720 24 fps progressive wide
      • 1280x720 30 fps progressive wide
      • 1280x720 60 fps progressive wide
      • 1920x1080 24 fps progressive wide
      • 1920x1080 30 fps progressive wide
      • 1920x1080 30 fps interlaced wide

      In presenting these on a monitor, your receiver/settop box/whatever is supposed to turn them to a format that your monitor can handle. This will typically be one of these four:

      • 480 row 60Hz interlaced
      • 480 row 60Hz progressive
      • 720 row 60Hz progressive
      • 1080 row 60Hz interlaced
      • It is noteworthy, though, that some videophile monitors can handle, and set-top boxes deliver, 1080 row 60Hz progressive.

        As for the presence/absence of interlacing, I agree that it is very bad to use interlacing at the strem level. This should be eliminated. I would make an exception for the 480 modes, because the material may have been originally captured on NTSC videotape, in which case some sort of conversion would have to take place to get a progressive image, and I feel very strongly that conversions should never be done for broadcast unless absolutely necessary (as when showing PAL/SECAM native material).

        On the other hand, at the monitor level, if you have an interlaced monitor, I don't think that is a major issue. In 1080 mode, the best picture that can be sent is the 30fps progressive stream. This can be interlaced for presentation on a cRT.

        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.

        Further, I would put forth that CRT's, in addition to being significantly cheaper than the alternatives, also put out a better picture than LCD (view from any angle; accurate color rendition; no lag), are less susceptible to burn-in than plasma (which will be killed by network bugs) and do not exhibit the rainbow effect of DLP (which, in fariness is not really all that bad). Their major failings are their physical size and power consumption.

      --
      www.wavefront-av.com
    3. Re:For the inevitable /.ing by Richthofen80 · · Score: 2, Informative

      Good sources of HD, such as Motorola 6200 series HD set top cable box, will allow you to choose output conversion prior to the signal leaving the box. That way, your TV will recognize the signal as native and not do a scale/conversion.

      As an example, if you own the above box, or the PVR box, (both are silver and provided by Comcast), do the following:

      Turn off your cable box, then press 'setup' on the remote. You'll get a different config screen, one which allows you, among other things, tell the box what 'resolution' to display. (1080i, 720p, 480p, 480i). The Motorola scaler seems to do a great job, I'm not sure the algorithm / method, but I'm pretty sure it doesn't dice the 1080i fieldset then scale/stretch.

      Early plasma TVs who have a native resolution of 852x480, and who have bad scalers in the TVs, benefit by setting the resolution to 480p.

      I got lucky, my plasma has an excellent scaler so I left the cable box settings as-is.

      --
      Reason, free market capitalism, and individualism
    4. Re:For the inevitable /.ing by Infinite+Entropy · · Score: 3, Interesting

      Just wait for the thin CRT technology to come out. It uses millions of tiny electron guns instead of one, and if it fulfills its promise it will destroy plasma and LCD.

  4. Resampling by FlyByPC · · Score: 5, Insightful

    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.
    1. Re:Resampling by gyg · · Score: 3, Interesting

      The only effective limitation comes from linear algebra - there are only as many degrees of freedom as there are pixels, so if you downsample, you *always* lose data, like it or not.

      However, even this is not a problem in practice since in real-world pictures nearby pixels are not independent. By using an appropriate encoding dictionary such as wavelets, which zoom in on sharp edges and economize on flat surfaces, you can shrink a typical picture by something like 90% without visible quality loss.

      Now since wavelets are actually continuous functions, you could then convert from wavelet representation to upsampled signal, with no information loss. I imagine this could give sharper edges as wavelets are better at egdes than Fourier.

      The problem of upsampling well is very similar to making a blurry image crisp - called deconvolution. The problem in doing that is that any noise in the blurry image gets amplified, must be filtered out etc...

      Moral is that clever algorithims have been around for ages - the effective limit is whether they can be done in realtime.

  5. Which Models? by goldspider · · Score: 5, Interesting

    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
    1. Re:Which Models? by David+Leppik · · Score: 5, Interesting
      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.
      Yes. Go to a showroom and look at the displays. If you see some that have greater vertical resolution than the non-HD models, there you go. If you can't see a difference, then it doesn't make a difference.

      If there is a difference you can't see but could learn to see, don't learn; it will not bring you joy, it will only make you miserable or annoying. Long ago I learned to see the FFT distortion in JPEG and MPEG images. Has it made me happy? No. I end up making the JPEGs on my website bigger than everyone else's so I won't see wrinkles on people's faces that are apparently invisible to everyone else. And I can't stand to watch satellite television on a big screen TV because of the annoying compression artifacts.

    2. Re:Which Models? by Total_Wimp · · Score: 4, Funny

      Yes. Go to a showroom and look at the displays. If you see some that have greater vertical resolution than the non-HD models, there you go. If you can't see a difference, then it doesn't make a difference.

      This is not a solution.

      At Best Buy and Circuit city I've seen lots of SD signals on HD displays. How on earth am I going to know if it's the set or the signal that's producing all those jaggies? Ask? At Best Buy? I might as well ask them to build a moon rocket while they're at it.

      Knowing the stats won't neccessarily guarantee you a better picture, but it is a better place to start.

      TW

    3. Re:Which Models? by sxdev · · Score: 2, Informative

      Yes. If you connect and display a alternating black and white interlaced frames, you should get a mid-gray if it is combining the two. If you get pure black or pure white then it is showing one of the interlaced frames and throwing away the other one. (as the article claims they do)

    4. Re:Which Models? by twelveinchbrain · · Score: 3, Insightful

      Yes. Go to a showroom and look at the displays. If you see some that have greater vertical resolution than the non-HD models, there you go. If you can't see a difference, then it doesn't make a difference.

      That's not necessarily good advice. At the showroom, everything you see is optimized for selling the display. You might not notice any problems until you start to view content outside of their controlled environment.

      --
      Not Found
      The requested URL /signature.html was not found on this server.
    5. Re:Which Models? by Shkuey · · Score: 3, Informative

      If you're buying a 720p (or close to 720p as many are slightly off) set that is less than ~3,000 USD the answer is easy: All of them. If you're in the market for a high end unit then it is a two-step process. You need to find what kind of scaler is built-in, commonly you'll find third party scalers like Faroudja, and then research the scaler to determine how it functions. Unfortunately some manufacturers (Sony!) build their own scalers and they're probably not going to tell you how it works.

    6. Re:Which Models? by maraist · · Score: 2, Insightful

      If you're buying a 720p (or close to 720p as many are slightly off) set that is less than ~3,000 USD the answer is easy: All of them.

      The problem though is that it's BS that the cost of the processing represents affects the price of a multi-thousand dollar system. I can't imagine that a simple $100 PC video card couldn't be stripped of it's bare chips and used as the filter between what-ever proprietary system they use and the input signal processor. It can't possibly cost more than $500 to push an off-the-shelf component into their system. Since base HD-TV's are just above $1,000 these days.. Then such a low-end system of superior down-sampling shouldn't cost more than $1,500.

      I understand that most of these monitors have end-to-end proprietary solutions, and thus are internally limited to processing power and not extensible as I've said above. But if you can make a high-cost low-volume chip, then somebody else can make another one that IS extensible for no greater cost.

      The problem ISN'T that it costs them a lot to make, but that they would prefer to sell the high-cost (and thereby high profit-margin) sets. So if they're going to sell a cheap-o $1,000 set, then they want to artificially restrict it's capabilities. So they use a $50 CPU instead of a $150 CPU (made up numbers). Of course I'd rather pay $1,100 than $1,000 for a TV that uses a better CPU. But they'd rather me buy the $1,000 set now and when I can afford a $5,000 set, buy it again.

      Note these are unsubstantiated allegations; take them at face value.

      --
      -Michael
    7. Re:Which Models? by JohnsonWax · · Score: 2, Insightful

      At Best Buy and Circuit city I've seen lots of SD signals on HD displays. How on earth am I going to know if it's the set or the signal that's producing all those jaggies? Ask? At Best Buy? I might as well ask them to build a moon rocket while they're at it.

      So don't go to Best Buy or Circuit City to evaluate your monitors! Go to a high-end video shop to evaluate your monitors and then go to Best Buy or Circuit City to buy them if the prices are really that much better.

      Seriously, do you want to solve the problem or just argue?

  6. Workaround is to use an HTPC... by Rectal+Prolapse · · Score: 5, Informative

    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.

    1. Re:Workaround is to use an HTPC... by As+Seen+On+TV · · Score: 2, Insightful

      it will combine the 1080i field pair into a single 1080p signal

      This will, of course, suck.

      There are two different ways to get 1080i material. You can either shoot some other format at 24 frames per second and convert it to 1080i, or you can shoot 1080i.

      If you shoot film or 1080/24 at 24 frames per second and convert to 1080i, there are a set of well-defined tricks you can use. These tricks are collectively referred to as "pulldown." It's possible to remove pulldown, which is great ... except these automatic schemes usually break on cuts, which means they introduce more artifacts than they remove.

      If you shoot at 1080i, like for a sporting even or live broadcast, then combining the two fields into a single 1080p frame is going to make it look like ass. Because when you shoot 1080i, you're capturing the upper field 16 milliseconds before you capture the lower field, which means your subject moves between capturing field A and capturing field B. If you then just shove these two fields together, you're going to get a blurry picture.

      It's a widely repeated fallacy that 1080p is inherently superior to 1080i. The two formats are equivalent in most respects, and going from one to the other is not a "up-conversion." If done wrong, it can be a down-conversion.

    2. Re:Workaround is to use an HTPC... by MojoStan · · Score: 2, Informative
      A $200 19" CRT computer monitor will display more than 1080p (let alone i) with no problem.

      But does a $200 19" CRT have enough "dots" to display all the pixels in a 1920x1080p picture? (I'm not sure. I really want to know.) My knowledge of display technologies is limited, but I think 19" CRTs in this price range don't have enough "dots" (calculated from dot pitch) to display all of the pixels and will not give a "true" 1920x1080p picture.

      Example: I've been thinking about getting a Samsung 997DF, which has a max resolution of 1920x1440 (a resolution I'd only use for 1080p video). However, it also has a horizontal dot pitch of 0.20mm and a viewable width of about 14.4" (about 365.76mm). That's about 1829 viewable dots across the screen, which is less than the number of horizontal pixels in a 1920x1080p picture.

      The ability to display 1920x1080p is the biggest reason I'd choose a $200 19" CRT over a $230 17" LCD. However, if the 1080p video is "messed up," then I'd rather get a 17" LCD and just convert everything to 720p.

      --
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  7. When is 720p Not 720p? by t_allardyce · · Score: 5, Insightful

    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..

    --
    This comment does not represent the views or opinions of the user.
  8. If you can't see the problem, is there a problem? by ...+James+... · · Score: 3, Informative

    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.

  9. Same thought by SuperKendall · · Score: 2, Insightful

    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
  10. Well, a little worse, actually... by AtariDatacenter · · Score: 3, Informative

    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.

    1. Re:Well, a little worse, actually... by Ironsides · · Score: 3, Informative

      Current camera technology can't provide full detail at 1920 pixels yet

      High, I just got back from NAB show in Las Vegas last week. The vendors were had HD Cams that would film and record 1920x1080i. That somepoint is today.

      --
      Fly me to the moon Let me sing among those stars Let me see what spring is like On jupiter and mars
  11. Good Ol' CRT by goldspider · · Score: 5, Insightful

    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
    1. Re:Good Ol' CRT by GatorMan · · Score: 3, Insightful

      You must live on the first floor and I also assume you don't relocate often. Try getting a 215lbs. 36" CRT HDTV up a couple flights of stairs. Even with the home delivery options you're lucky if the thugs don't damage your set, your building, or both.

    2. Re:Good Ol' CRT by The-Bus · · Score: 3, Insightful

      Well, not sure what you mean by CRT but I would say the compelling reason is size. CRTs can only be so big. If you want to go bigger, you can go with what I call the "MTV Cribs" TVs, plasma/LCD, etc. or you can go with a quality RPTV or a projector. I have yet to see a plasma or LCD that has a better quality picture than a decent RPTV.

      --

      Small potatoes make the steak look bigger.

  12. its really too bad by bassgoonist · · Score: 2, Insightful

    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.
  13. This is what you get..... by nathanmace · · Score: 3, Informative

    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.
    1. Re:This is what you get..... by Tiroth · · Score: 2, Insightful

      The problem is, how do you do the research? The audio/video publications out there have not even come close to adopting a standard set of measurements that would quantify the performance of processors that need to perform complex tasks like scaling, 3:2 pulldown, etc. The results from different chipsets are all over the map (chroma key errors, cheats, lame algorithms), and it's rare to be able to get any information at all on new products. You just have to wait 6 months until someone that actually knows what they are doing throws a review up on the web.

    2. Re:This is what you get..... by Zed2K · · Score: 4, Insightful

      Kind of hard to "do your research" when you can't find out how the conversion takes place or can't understand how it all works. This is not a consumers fault kind of thing. This kind of information is not made known unless people ask the question. Who would have thought to ask a question like this?

  14. Should have bought a 1080i screen then! by node+3 · · Score: 5, Insightful

    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.

    1. Re:Should have bought a 1080i screen then! by Zed2K · · Score: 2, Informative

      There are 1080p DLP tv's coming this year from samsung, panasonic, mitsubishi.

      Personally I'm getting a samsung 6168 model.

    2. Re:Should have bought a 1080i screen then! by mquetel · · Score: 3, Informative

      Sharp has several models of 45" LCDs that are 1080p. The technology is available, but really expensive. See here: http://www.sharpusa.com/products/ModelLanding/0,10 58,1426,00.html

  15. Hey, Bloggers... by Gruneun · · Score: 5, Insightful

    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.

  16. Consider the source too! by Rectal+Prolapse · · Score: 3, Informative

    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!

  17. spatial vs temporal resolution by Phearless+Phred · · Score: 5, Informative

    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.

    1. Re:spatial vs temporal resolution by pe1chl · · Score: 3, Insightful

      But this is true for SD display on a double-scan TV as well.
      The "digital feature box" in the TV is supposed to combine the two fields into one single frame. This is usually referred to as "motion compensation" or some other nifty marketing term.
      This is what separates the cheap from the expensive TVs.

  18. The clever algorithm is a "Fourier transform" by roystgnr · · Score: 5, Informative

    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.

    1. Re:The clever algorithm is a "Fourier transform" by Anonymous Coward · · Score: 2, Informative

      Agreed it's lossless.

      Disagree with second paragraph. Upsampling should have more Gibb's ringing around the discontinuities in the image. This is why one introduces a Hannning or Hamming window during sinc interpolation. Whether that manifests itself as a blurring depends on the context of the discontinuity within the image. Upsampling via FT is not the same as linear (or even simple non-linear) weighting during digitization.

  19. ED displays by justforaday · · Score: 2, Interesting

    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.
    1. Re:ED displays by Humba · · Score: 2, Informative
      The ED vs. HD debate is one of the most heated that you'll find at AVS Forums.

      Many current, popular 42" plasma sets are either "HD" resolution (typically around 720 lines) or "ED" resolution (480p). No one argues that the HD doesn't provide a slightly superior picture for HD content, but many argue that ED is preferrable for non-HD (SD) and DVD sources. And the price difference between the two can be dramatic. ($2500 vs. $5000).

      For that $ difference, I was willing to compromise. Some pureists will make a different choice. I'm very happy with my ED Panasonic Plasma, and am hoping that in five years the price of direct-view HD sets will be within my reach.

      --H

  20. only HD is HD by Anonymous Coward · · Score: 2, Interesting

    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.

  21. Re:Resampling: Imagine a 1-pixel-wide line by G4from128k · · Score: 4, Informative

    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.
  22. Re:misty by eyegor · · Score: 3, Insightful

    There has been a similar issue for years with audio amplifier specs.

    Mfgrs usually tout their amps with having "200 watts of pulsing music power" which usually means 100 watts per channel peak. In reality it's more like 70.7 watts/channel RMS (assuming they're not still lying).

    --

    Don't anthropomorphize computers, they don't like it.
  23. Comment removed by account_deleted · · Score: 3, Insightful

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  24. Comment removed by account_deleted · · Score: 2, Informative

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  25. Not news - Buy a scaler. by GoRK · · Score: 4, Informative

    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.

  26. More Like When is HD Not HD by Myriad · · Score: 3, Informative
    While this is an interesting issue, and one I hadn't heard of before, it's only one of many mines in the field of HD.

    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'
    1. Re:More Like When is HD Not HD by Space+cowboy · · Score: 2, Informative

      - 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.

      I have a Mitsubishi X390U linked up at home - it's your typical 1024x768 resolution. I've got the comcast HD box linked up to a TiVO (SD only) and (HD feed) directly into the amp's component inputs. The result is that I can switch between HD & SD at the flick of a button. It all gets projected onto an 8' screen.

      The difference between HD footage and the *same* SD footage is that of night and day. Heavily rescaled or no - at the end of a movie the tiny credit text is easily readable on HD (as opposed to a blurred just-about-legible mess on the SD feed). The movie itself just blows me away. Every time :-)

      Same source, same amp, same projector. World of difference.

      So, (and I'm not disagreeing over the scaling), you do get an excellent upgrade from SD when using a 1024x768 projector.

      Simon

      --
      Physicists get Hadrons!
  27. Comment removed by account_deleted · · Score: 4, Insightful

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  28. there are not many 720p displays to begin with. by Mark19960 · · Score: 2, Informative

    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.

  29. Re:Not as Alarming as it Sounds by wiredlogic · · Score: 2, Insightful

    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

    If you receive an OTA broadcast or cable signal in 1080i then you don't have any control over the video source. Since the broadcasters are split between 720p and 1080i this is a real issue.

    --
    I am becoming gerund, destroyer of verbs.
  30. No, that's the standard by Alereon · · Score: 3, Informative

    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.

  31. How to prove/disprove it easily. by Stavr0 · · Score: 4, Interesting
    Simply provide a 1080i test pattern made of alternating horizontal lines where the left half is black lines on even scanlines, white lines on odd scanlines and the right half is reversed (white-even,black-odd)

    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.
    1. Re:How to prove/disprove it easily. by interJ · · Score: 2, Informative

      You forgot one result: Your screen flashes black to white at 60fps. This is a result of resizing each 1080i field to 720p and displaying it. While it wouldn't give good results for this example, it would probably look the best for real-world signals, because nothing would be discarded, and there is no good way to deinterlace without showing some artifacts or blurriness.

  32. Comment removed by account_deleted · · Score: 3, Informative

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  33. Much ado about nothing. by gblues · · Score: 3, Informative

    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

  34. Look at the Source by cheinonen · · Score: 2, Informative

    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.

    1. Re:Look at the Source by espressojim · · Score: 2, Insightful

      Why can't we use our computers to scale images? I have a 720p projector (Sanyo Z2), and I scale my movies up to 1280x720 on the fly. You need a bit of processor power, but it's much cheaper than the scalers that are mentioned in your post. In addition, I'd assume that I can buy newer software packages and 'upgrade' my algorithms more easily than selling my scaler and buying a new one...

  35. Easy Fix by KrackHouse · · Score: 2, Informative

    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
  36. Re:If you can't see the problem, is there a proble by mcg1969 · · Score: 3, Informative

    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.

  37. Re:It's not the TV. by MalHavoc · · Score: 2, Insightful

    That's fine advice until you realize that at this point in time there is NO source of 1080p material. Sure, you can scale up to it, but then you're interpolating, and you're not really seeing true 1080p. It's nice to own a unit that can display 1080p natively, but it might be a while until we get a native source for it. You're damn right about the tubes in a CRT though. Those suckers are expensive to replace, compared to replacing a single bulb in an LCD or DLP projector. It cost me three times as much to replace the CRT bulbs in my Pioneer RPTV, compared to the single bulb in my Runco projector.

  38. Silicon Optix ASTROTURF? Naw, it couldn't be... by StandardCell · · Score: 2, Informative

    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.

  39. Re:misty by Jeremy+Erwin · · Score: 3, Funny

    We all know that the 100W at 0.08THD in an 8-ohm load at 100-10,000Khz is the far superior amp.

    You don't care much for bass, do you? And most people find it difficult to listen to ultrasound all day.

  40. CD Audio all over again. by karlandtanya · · Score: 3, Interesting
    Remember when CDs first came out?


    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
  41. Re:misty by Phreakiture · · Score: 2, Interesting

    Mfgrs usually tout their amps with having "200 watts of pulsing music power" which usually means 100 watts per channel peak.

    I call this the Radio Shack method of describing the system, because it was originally used only by Radio Shack, but now is used by everyone -- the system power is described as the sum of all channels, not the value of one channel.

    As such, I have a 420W sound system in my living room that, 15 years ago, would have been described as 70W. More likely, it would have been described as 70/70/70--70W main, 70W surround, 70W subwoofer (yes, it is a small system, but fully appropriate to the room).

    On the peak/RMS issue, good amps give RMS and have peak listed on the specs page. Sometimes the peak exceeds the typical sine-wave ratio of RMS=.707*peak because not all sounds are sine waves. My previous amp was a good example. It was listed as a 60W (per channel) amp at 8 ohms (15W surround, no sub, no center) but could, according to the specs page, deliver 120W on a peak to the main channels. This system was replaced last Decmber after 15 years of service. Coupled with a set of Harmon-Kardon speakers, it rocked pretty hard.

    --
    www.wavefront-av.com
  42. Decide for yourself by DumbSwede · · Score: 2, Interesting
    I have a NEC1351 projector and can display in 1080i 1080p and 720p. I have looked in the show room and noticed a huge range of qualities in HDTV quality. Upconverting standard definition is by far the largest area of quality difference between various models, but that is a bit of an aside to this discussion. I have always been surprised at the number of show room models that wimp out at 720p and not even true 720p but some weird non 1280 horizontal number that has to be extrapolated no matter what the source. Three beam rear projection tube models generally support all resolutions, but have far less actual resolution than the raw numbers they sight on their spec sheets. My 1351 looks stellar compared to anything you will find at BestBuy, but I have done a lot of tweaking, and it is still short of absolute perfect 1080 performance, having to do with a range of factors I won't go into here. The point is even a high-end machine like mine is currently not maxing out the quality of a true HDTV signal yet. The HDTV signals themselves are of so huge a variance of quality you have to wonder what kind of Rube Goldberg solutions they are using behind the scenes in some cases.

    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.

  43. Shameless Atari / Amiga Plug by tjstork · · Score: 5, Interesting

    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.
    1. Re:Shameless Atari / Amiga Plug by Shalda · · Score: 2, Interesting

      That's a a bit of troll, wouldn't you say? In the EGA/VGA (I think CGA as well) spec, you can check to see if the card is in a vertical retrace and swap buffers then. It's rock steady as well. Compare this with the approach taken in the Commander Keen games where they achieved very smooth side scrolling by adjusting the offset of the video buffer on the card. One only had to draw a few percent of the screen and move some sprites.

    2. Re:Shameless Atari / Amiga Plug by tjstork · · Score: 4, Informative

      The difference is that EGA/VGA you had to poll the card, but on the Amiga and even the Atari, you actually got notified by an interrupt. When you got the interrupt, you could be reasonably assured that there was no latency between the interrupt trigger and the event as interrupts ran at such a mega priority. And on those systems too you could also specify the memory window versus the display window and also scroll by adjusting the memory pointers as well as some shift registers. It just looked really, really good.

      --
      This is my sig.
    3. Re:Shameless Atari / Amiga Plug by awfar · · Score: 2, Interesting

      And, I would add if IIRC, the Amiga had an intelligent chipset and a local bus (chip vs. fast ram) for video and sound, and the autonomous chipset would DMA from/to using an abstracted display (command list) list, fully using interrupts to inform of events like retrace, both horizontal and vertical, I think, full hardware sprites and collision support; the audio could dma and play audio autonomously; set registers and a dma pointer and go. The CPU was doing other very important things like OS work and calculations, etc., which with the OS made it the first true multitasking home PC OS I had ever used, and it was smooth; not perfect, but it was doing everything, mouse, gui, video on many screens ,stereo sound on a 10MHZ 68000!

  44. What's the problem? Monitors are just monitors by bradleyland · · Score: 3, Insightful

    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?

  45. Re:When is 720p Not 720p? by Ibiwan · · Score: 3, Interesting
    the DCT is lossless; it just serves to separate the block information into lower-freqency components at the top left of the block, gradient to high-freq components at the bottom right of the block. The artifacts come from a lossy process where they divide the matrix, element-wise, by a matrix with ones in most places but higher and higher numbers as you go toward the bottom right. The end result is, you throw away partial information on your higher frequencies, in a pattern that the JPEG committee's research decided people can't see. Of course, you can further raise the factors from there, which most people do, which is why too many images show the blocking.


    Incidentally, the image is further compressed by

    • converting the block to a linear array of data by reading in a zig-zag pattern from the top left
    • using (lossless) run-length encoding on that bit stream (or on the data as bytes or words, not too sure on this point)
    • compressing THAT output with a (lossless) entropy coding; I believe it's the huffman family of algorithms.
    --
    -- //no comment
  46. Re:Here's how to tell. by Total_Wimp · · Score: 2, Insightful

    I totally agree with the the idea of your post, but the actual practice is a bit different.

    First off, DVHS and HDTV PVRs exist in tiny numbers. I am not one of the guys who owns one. Neither are the vast majority of the people reading your post. It's a great idea, but a bit of a stretch to ask someone to purchase equipment that costs half a grand minimum before even going out to purchase their first HDTV. Once again, great idea, just not something very many people are going to be able to take advantage of.

    Ok, number two: think of the specialty shop in your area that has a wide variety of HDTVs set up and ready to plug your box into. Having trouble? Me too. All of the specialty shops in my area have, at best, half a dozen sets. This is pretty far away from variety. I'm not trying to knock these guys. I bought my speakers from a specialty shop and got a good deal on some great speakers. I love those guys. But their monitor selection was pathetic, just like every other "home theater" shop I've actually walked into in my area. Are you _ever_ going to be able to see the actual display you're interested in, or just something fairly close?

    Finally, what about Best Buy with your own content? Well, this is a problem too. A big problem. Let's say you showed up at BB with your own source material and you happened to find the one guy in all the BBs thoughout the land that was very knowledgeable, very friendly and didn't mind at all walking around with you answering your questions and helping you set up your PVR to every box you were interested in. Well, what about the sets? How are they calibrated? Have they ever been calibrated? Did they set that CRT down hard and screw up the guns? Have they been showing their plasma monitors at full brightness for 12 hours a day for half a year? Are those dead pixels typical of the manufacturer or unique to that one display? To put it succinctly, when you go into that menu and choose the defaults for the display you're interested in, how do you know that those defaults are typical of the box you're going to open up at home? How do you know if the set next to it is just as bad, or actually much closer to factory defaults?

    I know, you can glean a lot by looking at the displays, but it's far from the only place to look. Even good sets will often look like crap at the big box store. I hate to say it, but this is one place where stats will often paint a better picture than the picture you see in front of your eyes at the store.

    TW