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HD-DVD: What will the aspect ratio be?

Discussion in 'TVs' started by 00fjackson, Mar 19, 2005.

  1. 00fjackson

    00fjackson
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    Does anyone know what format HD-DVD will be encoded as or has it not been finalised yet?

    It might be mandatory 4:3 as is the current DVD, in which case the best resolution we will get on a 16:9 set is full vertical resolution but only 4:3 horizontal resolution. (Anamorphic DVD).

    I am hoping that it will allow full 16:9 image size for full 1080i/p resolution. This would make most sense as nearly all HDTVs are 16:9 ratio anyway.

    Please help.
     
  2. mike7

    mike7
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    My understanding is that HD transmissions and, presumably any recorded material, are not anamorphic but is 16:9 from source to receiver. Can someone confirm this please.
     
  3. Quickbeam

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    Yes, there is no such thing as a 4:3 HDTV broadcast.

    High-def content on HD-DVDs and Blu-ray content will be encoded in true 16:9 aspect ratio, not anamorphic 4:3. Old TV shows and films shot in 4:3 format will be presented in a 16:9 pillarbox. 2:35:1 movies will be presented in a 16:9 letterbox.

    What is not clear yet is whether HD analogue component outputs will be included in the players (it seems unlikely), or what frame rate will be used for Region 2 movie transfers: will they be encoded in native 24p on the disc, or 25p with 4% speed-up, as this the case with PAL designated SD-DVDs? At this point it's all speculation.
     
  4. Quickbeam

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    A film encoded in 1080i at 50Hz is already progressive so it's really easy to deinterlace. Whether any HD-DVD or Blu-ray player would actually output 25p or 50p is another matter: we simply don't know. Even if your TV doesn't accept 1080p, any half-decent display with film mode detection should be able to take the 1080i 50Hz signal and display it as 50p. Progressive displays without film mode detection should be avoided!
     
  5. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Film mode detection of 1080i material is extremely rare.....

    Current DVDs require film mode detection yet there is pretty big varience in performance of devices trying to achieve this consistently.

    I completely agree though that recording progressively then outputting 1080i for film detection to reconstitute the whole frame is the way to go.

    Gordon
     
  6. pdundas

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    It is at the moment (there is one de-interlacer which does it properly but I forget which), but with the next generation of chips it should hopefully become a lot more common.

    Most de-interlacers both external and built into display devices at the moment do a simple "Bob" de-interlace delivering a 540p result.

    HDTV uses square pixels and when you work it out both 1280/720 and 1920/1080 equal 1.7 recuring (i.e. 16/9) which gives your answer.
     
  7. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Paul: I've seen the two chips you are talking about doing 1080i to p....Work in progress....there are going to be different levels of performance in this field just as there is with the current SD chips.

    Gordon
     
  8. Quickbeam

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    I'm surprised to hear that 1080i film-mode detection is so rare. I'm aware that PAL/NTSC film mode detection on current progressive displays is a pretty hit and miss affair, but if a display is HD ready and has SD film mode detection, many people would assume it would also include 1080i film mode detection. After all, what is the point of having a progressive display if it's going to degrade the quality of psf signals? Given that HDTV has been available in some 60Hz countries for years I'd have thought that 1080i film mode detection would be a priority for display manufacturers in order to counter the effect that interlacing has on 3:2 pulldown.
     
  9. beeblebrox12

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    What do you guys mean by "1080i film mode detection"?
     
  10. Stephen Neal

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    In 50Hz terms I guess they mean detecting that there is no motion between the two 50i fields, and thus that the source is 25Hz progressive (i.e. film or 25p video). This means that no interpolation is required to convert the 50i signal to 25p or 50p - instead the two fields can be merged to create a frame with no real processing. (Whereas if there is motion between the fields - as would be the case with a "video" source - then all sorts of motion detection and processing are required to create a 25p or 50p signal)

    In 60Hz terms then film mode detection also involves 3:2 pulldown detection - where the extra field used to get 24p to 60i is detected.
     
  11. ahin4114

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    Doesn't the Crystalio deal with this? I'm pretty sure it does film mode detection, but whether there's an issue with the source resolution I'm not sure.
     
  12. beeblebrox12

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    If that's the definition, then 100% of the natively progressive HDTV sets I've seen do it. At least they say "deinterlacing with 3:2 pulldown" or something of the sort.
     
  13. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    They do 3:2 cadence detection on Standard Definition material....not high definition.

    The HD Leeza does it. Faroudja's discontinued 5000 does it. Terranex Xantus does it and in a week or two the Lumagen HDP and HDP Pro will do it (they are just finishing off the algorithms for the update just now)

    Gordon
     
  14. Louis Mazzini

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    If this is correct, it's extremely disappointing news: I'd assumed/hoped that 2.35:1 material would be anamorphically compressed into the 16:9 frame. It seems so obvious that this is the best way to go (for projection via an anamorphic lens), I can't think why it would only be letter-boxed.
     
  15. StooMonster

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    Because more of HD_DVD / BluRay's potential customers will have fixed 16:9 ratio screens (plasma, LCD, RPTV, etc.) than projectors fitted with anamorphic lens?

    In which case 2.35:1 is perfect when letterboxed on 16:9 screen.

    But I guess what you're saying is that the player should format the content to match the screen: i.e. in raw format it's anamorphic 2.31:1 but the player would downscale image to 16:9 if required, just like DVD players letterboxing 16:9 material when displayed on 4:3 display.

    StooMonster
     
  16. Alistair_M

    Alistair_M
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    So if its not anamorphic for high def, and movie is rated at 1920 x 1080:

    How many vertical lines of information will there be for 2.35:1 letterbox movies - it must be a lot less than 1080? But 1.85:1 movies there will be 1080 lines, right? and also 1080 lines for 4:3 material? Am I right?
     
  17. Dutch

    Dutch
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    Hi Alistair,

    I worked it out as 803 lines being used for a 2.39:1 ratio film and 1038 for a 1.85:1 film. Only 1.78:1 widescreen video and 4:3 ratio material would fill the full 1080 lines. Hope this helps.

    Steve
     
  18. beeblebrox12

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    This is the first time I hear about such thing, since I've been reading on this stuff for the last 5-6 years. Is it something 25Hz/50Hz world related? How can you test (and can you at all) that on a 60Hz HDTV?
     

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