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Is 1024x768 HD?

Discussion in 'TVs' started by Istanbul_Kop, Nov 10, 2005.

  1. Istanbul_Kop

    Istanbul_Kop Well-Known Member

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    Been looking at a few 'HD Ready' TVs, the ones in my price range seem to have a resolution of 1024x768....is this ok for SKY HD, XBOX360 etc?

    Been looking at the Samsung PS42S5HX.

    Thanks
  2. neilmcl

    neilmcl Active Member

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    Not wanting to get into the "whats really HD or not" argument but if you see a TV with the official "HD Ready" logo in the UK you can be assured that it will be suitable for HD sources such as Sky HD, Xbox360, BluRay/HD-DVD etc.

    Obviously if you can find a screen with a resolution of 1920x1080 and can support 1080p then is will be true High Definition but this is like the Holy Grail at the moment and certainly not available in plasma for some time yet.
  3. Istanbul_Kop

    Istanbul_Kop Well-Known Member

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    OK, nice one, thanks.
  4. Welwynnick

    Welwynnick Active Member

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    Have a look at the current thread about sub-50" plasmas.
    Let's not do it all over again! Without being controversial and in summary:
    Not HD:
    Older 42" plasmas @ 852 x 480
    HD ready:
    37" plasmas @ 1024 x 720 - display HD adequately
    42" & 43" plasmas @ 1024 x 768 - display HD a bit better
    50" & up plasmas @ 1280 x 768 and 1366 x 678 - display HD best at the moment
    Future plasmas:
    50" & up plasmas @ 1920 x 1080 - ultimate HD quality.

    But remember that there are many other factors that affect picture quality other than resolution (and take most contrast figures with a pinch of salt).

    Nick :)
  5. loz

    loz Active Member

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    ANd what about other display technologies?
  6. Welwynnick

    Welwynnick Active Member

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    The question was about 1024x768 displays, which I took implicitly to be about plasmas.
    I think most DLPs are 1280x720, and most LCDs 1366x768, so all good.

    Nick
  7. 10bii

    10bii New Member

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    Instanbul you need a tv with at least 1280x720 resolution for it to be able to show the minimum HD resolution. Don't believe anyone that tells you otherwise. Anything less will give a degraded resolution picture.

    720p = 1280x720
  8. Kevo

    Kevo Active Member

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    It's a good job that the human eye doesn't notice much change in resolution in the vertical res as it does in the horizontal then.

    Same as current SD 16:9 which is 4:3 digital ratio. Don't think anyone can see any quality loss if it's shown in 16:9 or squashed 4:3. Stretch it the OTHER way and the quality loss is clearly there to see.
  9. neilmcl

    neilmcl Active Member

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    The OP wants to know whether his choice of screen works with Sky HD and Xbox360, which it will. Lets not bring down this thread by turning it into another HD argument, keep it to the other thread please.
  10. 10bii

    10bii New Member

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    Yeah and I'm sure it is quite reasonable to assume that the original poster wants to actually see HD resolution. :)
  11. Evil Engineer

    Evil Engineer Member

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    Not available in plasma, but the Sharp LC45GD1E is 1920x1080 and can be tricked into taking a 1080p signal.

    So the Holy Grail is available and with that price tag your wallet will be fairly "Holy" as well!
  12. Welwynnick

    Welwynnick Active Member

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    Well he will. He just won't see HDTV resolution. Lets keep this in just the one thread, please.

    Nick
  13. 10bii

    10bii New Member

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    Standard definition displays with the proper input will be compatible with SKY HD.

    Don't play games with the guy's money! :mad:
  14. Welwynnick

    Welwynnick Active Member

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    That's why I qualified my answer by saying 1024x720 was adequate and 1366x768 was best at the moment. End of discussion.
  15. HeweyBoy101

    HeweyBoy101 Member

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    End of discussion?

    I'm not an expert, but wouldn't 1024*720 be a better match for native 720p HD material. Surely there will be some scaling involved to input the 720p signal into 1366*768. I don't have an HD ready TV, so have no particular bias at present. I did however see a Panasonic 37PV500 today in a shop (1024*720), with a 720p HD PC input. The picture was as good as I could ever want, from a viewing distance of 2.5 metres. I was intending to hold out for a 1080p panel, but now not so sure having read this thread, and having seen the quality on offer with the Panasonic. I am leaning towards a Panny 37" PHD8 panel + scaler (mayber iscan VP30 with truckloads of HDMI inputs - well 4 actually!)
  16. DanH

    DanH Member

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    Thats the whole point. Go and demo what you have narrowed your choices down to and decide with your eyes. For compatability sake, make sure whatever you buy has the HD Ready logo on it, and dont put too much faith into bigger numbers on a spec sheet. There is much more to image quality than resolution.
  17. loz

    loz Active Member

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    Well there may be no vertical scaling of the 720 but where do you think the other 256 pixels of the horizontal HD signal are going? HD is 1280x720.
  18. Stephen Neal

    Stephen Neal Active Member

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    Though it is also relevant to add that historically horizontal scaling has been higher quality than vertical scaling, though this may no longer be the case.

    Out of interest - how sophisticated are the vertical scaling algorithms used in 720->768 scaling in most sets. Are they based on multi-tap FIR-type filters?
  19. StevenBagley

    StevenBagley Member

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    That is only because you can scale video horizontally without having to worry about interlace since rescaling an interlaced image well is a nightmare -- you have to deinterlace it to progressive, scale, and then reinterlace to do it well. Although I imagine it is possible to combine parts of the steps, it gives you an example of the complexity of the task.

    With a progressive image scaling vertically should be as simple as scaling horizontal. Although the closer you get to unity scaling, the harder it becomes to get a good result. So 720 ->768 is much harder than say 576 -> 768 or 1080 -> 768.

    Steven
  20. loz

    loz Active Member

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    Worth noting that my 1280x768 Philips LCD allows you to show a 720 picture with small black borders, so no scaling. I am sure many other sets allow the same.
  21. Stephen Neal

    Stephen Neal Active Member

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    Yep - which is why some 720/768 line displays don't de-interlace 1080i to 1080p and then scale, and instead treat it as 540p I understand...

    Yep - that is what I thought - and why I asked!

    AIUI this is one reason that ALiS panels don't scale 1080i to 1024i - and instead crop. (Presumably they were originally designed for the original 1030i HiVision Japanese system that was expanded to 1080i by reducing vertical blanking?)

    (AIUI this was also one of the reasons 14:9 letterboxing wasn't included in the early digital TV set top boxes, as 14:9 letterboxing is more difficult than 16:9 - especially as it requires scaling in both directions)
  22. StevenBagley

    StevenBagley Member

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    Well bad ones will :) I suspect it is more to do with the amount of field store memory that'd be required to do it, and/or the availability of cheap decoder chips to handle it. Ideally, a deinterlacer will need to hold at least two 1080i 540 line fields at 2MB each (assuming 8bit YCrCb 4:2:2 encoding) as well as an output buffer at 1080p to store each deinterlaced frame and then a output buffer at the display resolution to resize into, which probably needs to be in RGB (and double buffered to stop flicker on the screen)

    That's 2x2MB for the fields, 4MB for the 1080p buffer, and what ever the display size is. That's at least 16MB of RAM needed. And then you need the processing grunt to chomp through it in realtime. Ideally, you'd want three or even five input fields (the field temporally coincident the one being displayed and then equal numbers either side of it -- hence the delay inherent in plasma and LCD technology) and so the RAM and grunt needed to process it increase. Of course, for SD you can just stick a few megs of RAM and an off-the-shelf chip to handle it -- although even some of them treat 576i as 288p :(

    Unfortunately, this means that manufacturers tend to compromise and just scale it as if it was 540p. Which has the unfortunate side effect of dropping the vertical resolution to almost sub-SD levels. If you have a 720 line cycle vertically in the 1080i image (i.e. about the highest level visible in 1080i signal) when you take it in the 540p domain you end up with a 360line cycle present in anti-phase (an alias signal) as I understand it. Whats worse is that it'll oscillate up and down between fields if you aren't careful...

    A 1080psf mode would be very nice and wouldn't need much more RAM or DSP power.

    It's very easy to generate a test pattern to see how a display is handling 1080i footage -- if you can feed 1080i to the display from the computer (via a HDV camera perhaps?).

    Steven
  23. Stephen Neal

    Stephen Neal Active Member

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    That all makes sense and confirms what I thought - though I hadn't really thought about the output frame-store being in 4:4:4 RGB rather than 4:2:2 YCrCb. The amount of delay this introduces is horrible if you are using plasmas in broadcast monitoring situations - especially if you also are pre-processing using Zandar style "virtual monitor stack" processors...

    I guess this is why people still suggest using external scalers for some set-ups - as at least with these you can control the scaling algorithms used to convert non-native sources.

    (I notice that earlier Sky receivers seem to have an SD 4:2:2 frame-store, even for their receiver rendered digital text, whereas later devices seem to have a 4:4:4 architecture, as fine detail on overlaid text on early receivers is not very pretty when it comes to coloured details, whereas later boxes look much cleaner?)

    If you need to feed HD to a display then I guess an HDV camcorder with HD analogue component outputs, or a Snazzio or similar HD replay solution would be the neatest way? The Snazzio will output full 1920x1080 video when fed with such, whereas the HDV camcorder will presumably be limited to 1440x1080 when replaying from tape?
  24. neilmcl

    neilmcl Active Member

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    C'mon you two lets keep this nice and simple so the rest of us can understand :)

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