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some hdtv questions

Discussion in 'Projectors, Screens & Video Processors' started by keyser, Jun 2, 2002.

  1. keyser

    keyser
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    Please explain this to me. In the us they have HDTV which is a much higher resolution image right, and they have progressive scan, is this the same thing? Like the gamecube has progressive scan, if I feed this to a HDTV do I then get a higher resolution picture. Do they have high resolution signals coming from the dvd players and computer or do the tv´s have line doublers or something. Could I get an HDTV from my pioneer 737 dvd player, or would it just have some progressive scan image?
     
  2. MarkTaylor

    MarkTaylor
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    As I understand it, there are a number of different HD signals, some progressive but not all.

    720p and 1080i for example seem commonly in use.

    i.e. 720 progressive, and 1080 interlaced.

    Don't get progressive vs interlaced confused with resolution, this just describes how the image is built up on screen. Progressive will built the enitre image in one scan from top to bottom, interlaced will buld the image in two scans, each filling every other line.

    DVD's cannot produce HD signals since the source material is not produced at the higher resolutions.

    If you read any of the USA forums you'll see a lot of analysis of SD (standard definition) vs HD (high Definition) signals. People are sometimes using expensive external scalers and signal processors to get a better quality progressive image from the lower quality SD sources, but the future there is clearly HD broadcast signals.

    For non-broadcast material I beleive they will soon have HD on D-VHS, but I suspect it will take the next generation of blue-lasers before we see 'DVD' HD material

    For current DVD's, the highest resolution image you will get from a DVD player is PAL at 625 lines. Even when you can get a PAL progressive signal out of a DVD, it is not as good as a 720p HD signal.

    Mark
     
  3. nfordenfield

    nfordenfield
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    As I understand, only 576 lines are for the picture the rest is for teletext. Also I recall that 500/520 lines is the max or near max for DVD.

    Just to further unravel NTSC/PAL/HD

    NTSC

    Standard 480i (720x480)
    Progessive/ Line Doubled 480p (720x480)
    Line Trippled/HD 720p (720x720)
    Line Quadrupled 960p (720x960)

    PAL

    Standard 576 (720x576)
    Progessive/ Line Doubled 576p (720x576)
    Line Trippled/HD 864p (720x864)
    Line Quadrupled 1152p (720x1152)

    HD

    1280x720

    1280x1080i and p (I think, the rest of the above is an extract from my Quadscan Video Scaler Guide)

    The figures in brackets are the actual pixel counts that the CRT/LCD/DLP or Plasma Panel sees.

    Hope this helps

    Nathan
     
  4. NickBull

    NickBull
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    I'm just reading about HD and DVHS D-Theater in Widescreen review, although most of it is over my head.

    It seems that normal HDTV will be 720p or 1080i. 720p actually takes up 50% more space on a DVHS D-Theatre tape than 1080i.

    HDTV can actually go upto 1080p, but you need a very top level 9inch CRT projector to resolve the sort of resolution you'd be outputting at that level.

    Progressive scan is 480p as mentioned. So 720p HD and a lot higher bitrate (19 MBPS for over air broadcast and 28.2 mbps for DVHS D-Theater) means a lot higher level of detail. DVD averages about 7 to 8 MBPS!
     
  5. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Nick,

    You've sort of cracked it. 1080i takes up same bandwidth as 540P...it's the lower bandwidth issue with 1080i that makes it the more popular format for braodcast in TV land and also for putting on tapes. It does, of course, suffer from the usual interlace artifacts.

    The 525 lines mentioned as being the limit of DVD is HORIZONTAL resolution. This is a measure of how many VERTICAL lines can be recorded and played back in the image. 576P, 480P, 1080i etc are numbers relating to vertical reolution or the niumber of horizontal lines....confusing isn't it.

    Gordon
     
  6. NickBull

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    Gordon,

    It certainly is! Not suprised half of what I read in Widescreen Review is gobledegook!

    Still, if you can get non scaled 720p from Dvhs D-Theater then it would certainly be beneficial to HD display owners.

    I'd say the chances of HDTV in the UK are pretty slim!

    Nick
     

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