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HD/HD-Lite How shall we define them?

Discussion in 'DIRECTV General Discussion' started by Tom Robertson, Aug 5, 2007.

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  1. LI-SVT

    LI-SVT Icon

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    May 18, 2006
    RAD,
    Do these resolutions:

    1920x1080i = HD High
    1440x1080i = HD Medium
    1280x1080i = HD Low

    represent 16:9, 14:9, 4:3 aspect ratios? Or are they all intended to be outputted at 16:9?
     
  2. P Smith

    P Smith Mr. FixAnything

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    W.Mdtrn Sea
    I would stick with parameters in profiles of thousands encoder's racks and after that will proceed to discuss theoretical chance put a legion of engineers who will control PQ of the miriad of channels on 24/7/365 watch and tweak the profiles.
    Are you really envisioning it will happen ?
     
  3. Stuart Sweet

    Stuart Sweet The Shadow Knows!

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    Jun 18, 2006
    No, but I wish it would. :)
     
  4. RAD

    RAD Well-Known Member

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    Aug 5, 2002
    Dripping...
    On page 17 of the PDF link I provided it says for 1280x1080 and 1440x1080 it's 16:9, for 1920x1080 is says 16:9 and "square samples", whatever that means.
     
  5. bobnielsen

    bobnielsen Éminence grise

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    Bainbridge...
    What that means is if the samples of the picture are square, 1920x1080 gives a ratio of 16:9 (1.778:1). 1280x1080 would be a ratio of 1.185:1 and 1440x1080 is 1.333:1. In order to fill the 16:9 screen, the samples for the latter two need to be rectangular.
     
  6. P Smith

    P Smith Mr. FixAnything

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    W.Mdtrn Sea
    Then we will see macro blocking, smear, lost of details, other hiccups forever if there no adherence to standard resolutions what our TV sets have and using starved bandwidth. :(
     
  7. P Smith

    P Smith Mr. FixAnything

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    That means your TV screen have SQUARE (exclude CRT) pixels, and any attempt to make 1/3 or 1/4 extension (1280 -> 1920 or 1440 -> 1920) will distort a picture.
    That's what we see now, thanks to the silly COMPRESS formats by A81 for DTH.
     
  8. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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    Nov 15, 2005
    Lamontcranston,

    I fully appreciate how difficult this topic truly is. "MPEG2 1920x1080ix60x19Mbs square pixels" is the top of the line in broadcast standards. (sidebar) And I do not for a moment expect to see MPEG4 or 1080p24 broadcast OTA in 10 years. Too many brand new TVs would go dark

    So a question becomes what is the equivalent PQ for an MPEG4 stream that might not use square pixels? I no longer directly oppose a replacement of square pixels with rectangular ones--if PQ does not noticeably suffer--tho I do highly suspect such conversions.

    I do note that the latest ATSC definitions include objective terms in their definitions for HD.

    Cheers,
    Tom
     
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