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Broadcasters... 720p or 1080i?

Discussion in 'TVs' started by paolo999, Aug 15, 2005.

  1. paolo999

    paolo999
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    Anyone know what Sky are going to favour in the UK?

    Anyone know what Fox is already favouring in the US?

    I know in the US ESPN is heavily behind progressive.
     
  2. danvitale

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    Both. 720p for sport, 1080i for other programming.
     
  3. paolo999

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    Damn. I was hoping for a different answer.

    If it was all going to be 720p then it would make the job of choosing an HD plasma so much easier.
     
  4. broadcastpro

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    In fact I think you will find that 1080 50i will be used for sports and general programming. The 720p format will be used for movie's where this format is already in use.
     
  5. loadsofleads

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    I thought 720P was the preffered choice for sport as it caused less motion probs :confused:
     
  6. Stephen Neal

    Stephen Neal
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    Err - dunno where you get that idea from. Very little drama is shot 720/60p.

    CBS, NBC, PBS and others are 1080/60i in the US for broadcast. Sport and entertainment for these networks is generally shot 1080/60i. Drama is shot 1080/24p (either on film or HD video) and transferred to 60i using 3:2 pulldown.

    ABC and Fox are 720/60p. Sport for these networks is shot 720/60p, drama is usually shot 1080/24p (and scaled to 720p with 3:2 frame repetition) though some stuff is shot 720/24p video (Arrested Development?) Film sourced drama may be transferred to 1080/24p or 720/24p - think it would depend.

    Certainly 720/24p is NOT a common US drama standard - 1080/24p is much more common. (Sony's HDCam CineAlta system in widespread use - also modified by Panavision - is 1080/24p.)

    The likelyhood is that the decision between using 1080/50i and 720/50p in the UK will be on a channel-by-channel basis (as it is in the US) - and not vary between programmes.

    It has been suggested that Sky will go with 720/50p for Sky Sports HD, but that they may go 1080/50i for HD movies (as 50p is overkill for 25p source material, but 50i is spot on, and the 1080 format carrying 25p stuff is sharper than the 720 format)

    The BBC is currently shooting HD in 1080/25p and 1080/50i - though it could cross convert to 720/50p for TX if it were to chose to.
     
  7. Stephen Neal

    Stephen Neal
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    60/50p or 60/50i are vital for smooth motion rendition on sports - 24/25/30p aren't good enough.

    720/60p has a slight edge over 1080/60i (which descends to the resolution of 540/60p on fast moving objects) - so is sometimes seen as better for sports.

    However many in the US think that their 1080/60i sport looks better than 720/60p - though this could be a limitation of the cameras and transmission system - not the underlying format.
     
  8. broadcastpro

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    All I can say Stephen, is wait until Sky launch there HD service in Jan. I think you will find sport is 1080/50i and the movie channels are 720/24p....
     
  9. nm10721

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    what will this mean for my Hitcahi PD5200 which only displays 1080@25 when sky hd programmes are broadcast at 720@50??
     
  10. IanPM

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    I do hope not, thats seems to be the wrong way round. Obviously the 'which format' debate will rage and rage. But the fact is, most US HD Drama (on which sky rely) is 1080i. In addition, most of the movie converted to HD from films will surely be in 1080i as well.

    It doesn't make much sense for Sky to re-encode stuff. So surely they will take the content they can from the rest of the world.

    And for sport, which is almost all originated by them, they may well go for 720p, progressive does make some sense for sport, I'm assuming thats why ESPN went with it...

    But then, I'm no expert.
     
  11. loadsofleads

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    That's the question every PD5200 owner has been asking for months, all we can do is clench the buttocks and pray to the a/v lord in the sky :lease:
     
  12. dsb

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    given that movies are only 24 frames, it seems rather pointless to go 720p for movies -while video material - eg sport, would certainly benefit from having 50 distinct frames.

    unless someone knows differently....
     
  13. tiburs

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    Most of the video component sets sold today are 720P (plasma, DLP RPTV) . What will be the effect of downscallng from 1080i to 720p for these sets?
    Should we wait that the 1080P reach the european countries and that prices drop ?
     
  14. Stephen Neal

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    Pretty certain that it won't be 24p... 25p possibly.

    The Sky receivers will only output 1080/50i and 720/50p AIUI - so 24p wouldn't be an option. Didn't know if Sky were supporting 25p formats for broadcast (rather than output) - suspected they weren't.

    Got no problem with 1080/50i for sport - currently there is very little 720/50p production at all. (Athens Olympics were 1080/50i, as was Euro 2004. Turin Winter games and World Cup 2006 will also be 1080/50i. BBC HD production of sport, for SD broadcast currently, is also 1080/50i)

    720/50p makes some sense for sport - but none for movies.

    Happy to wait and see - though I think we can be VERY certain that Sky won't be broadcasting in 24p though - it wouldn't be possible to simulcast in 50i SD using 24p. (With 25p/50i or 50p it would...)
     
  15. Stephen Neal

    Stephen Neal
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    1080/50i to 720/50p quality depends on the quality of the de-interlacer and scaler in use.

    Some treat the 1080/50i as 540/50p - and thus don't exploit the full 800ish lines of vertical resolution present in a 1080i signal.

    Better de-interlacers will convert 1080/50i to 1080/50p internally, and then scale to 720/50p, maximising the vertical resolution resulting.
     
  16. pjskel

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    That Hitachi spec doesn't state whether the 25 is progressive or interlaced. At a guess (because it makes the most sense) it would be prog, which means it should happily accept a 50 Hz interlaced signal of the same resolution.
    If not, then pray you don't want to watch any broadcasts at 1080/50i.
    Either that, or it'll downconvert, but that doesn't really make an awful lot of sense in practical terms. It's either a typo error or someone forgot to remember their i's from their p's and went with the latter instead of the former rather than checking with the tech dept.
     
  17. Stephen Neal

    Stephen Neal
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    Some organisations (including the EBU) use the definition 1080i25 to mean 25 interlaced FRAMEs per second, meaning 50 fields per second.

    Others use 1080/50i - which is arguably clearer (as it tells you how many different images there are a second) - to describe the same format...
     
  18. IanPM

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    It certainly is clearer, especially given that this is the first time the public has really had to think about fields and frames.
     
  19. nm10721

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    still doesnt explain what will happen with a 720@50hz signal going to a Hitchai pd5200, downscaling perhaps??

    Why can't Sky just flipping clarify this?
     
  20. loadsofleads

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    Probably don't know themselves, I'm sure some brave soul with a PD5200 will take the risk when Sky HD is launched........ won't be me though :clown:
     
  21. Dutch

    Dutch
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    I think the Sky HD box will allow you to select your preferred output (720p or 1080i) regardless of the received signal, as HD boxes in the US allow you to do.

    Steve
     
  22. Stephen Neal

    Stephen Neal
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    Yes - hopefully the Sky box will offer both fixed output formats and variable output formats - as most boxes in the US do.

    This way if you have a display that can only cope with one format, you can convert in the box to this format, but if you have a great display with a better scaler and de-interlacer than the Sky box one, you can output natively and get the display to scale instead.
     
  23. paolo999

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    What about drama/documentary/news etc... or is Sky initially just going to be sport and movies on HD?

    For 1080i stuff an ALiS plasma should a real contender. Apparently it just drops a few lines top and bottom and otherwise displays natively in 1024i.

    Hmmm. One moment I get sceptical about the Hitachi/Fujitsu, and then again it looks good.
     
  24. Stephen Neal

    Stephen Neal
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    Discovery HD, Artsworld HD and National Geographic HD are rumoured to be channels delivered on Sky HD (though not Sky channels) at, or soon after, launch.

    Discovery HD is 1080/60i in the US I believe, and it is expected that Nat Geo HD (which is due to launch in the US as well) will be 1080i. The bulk of the material Artsworld will get in HD will be 1080i - certainly all European HD arts coverage I know of is in 1080/50i.

    Of course these channels could be transcoded to 720/50p for TX - but if they stick with the native production resolution I would expect 1080/50i to be used on the Sky platform for them.

    It is still "wait and see" territory - my comments above are just informed guesses.

    I DO remain to be convinced that anyone would run a Movie channel in 720/50p though - when the source material will be 25p. I can pretty much guarantee that no European channel would be in 24p though - it would have to be 25p to deliver a decent quality PAL SD output. (48i would not be acceptable for feeding to VCRs, DVD recorders etc. and 24p to 50i conversion in real time would be nasty)

    Interesting comments about the Alis - does it really only have a 50Hz refresh rate though? I thought plasmas ran at much higher sub-field rates to deliver their greyscales, and I also though Alis alternated which lines it imaged on at the sub-field rate, not the field rate? (This would mean it would need a 1024p not a 1024i image source?)
     
  25. nm10721

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    thats what i'm hoping, i'll just keep telling myself that!
     
  26. paolo999

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    Yes, but I think the theory still works. If we are alternating our lighting of lines at 200hz say - we're still achieving the same persistent image as an old school 50i display - at least in terms of the interlace.

    I'd sooo like to get my hands on a 1080i source and try it with a Hitachi...
     
  27. paolo999

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    Actually no I'm wrong - if it is alternating faster than 50hz then the added persistence means you'd get combing on horizontal motion, which isn't really being "native" in the way I meant.

    Hmmm. This leads to a new question and a new post...
     
  28. Stephen Neal

    Stephen Neal
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    Yep - that was my point.

    It could be that ALiS is interlacing at sub-field rate not field-rate, and thus still requires a progressive source, and doesn't display interlaced material natively, instead converting 50i to 50p to 200i or similar?
     
  29. Quickbeam

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    From what I understand of ALiS panels, they do flicker (particularly noticeable from a PC input) but less noticeably than a CRT. This is because the electron gun on a CRT paints each line one by one (1, 3, 5, 7, 9 etc), and by the time it has drawn the last line the first has already begun to fade. On an ALiS plasma all the lines in each field are lit up simultaneously so there is less flicker.
     
  30. paolo999

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    Yep - correct and worth pointing out.
     

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