Why 480p and not 1080?

Discussion in 'Archived Threads 2001-2004' started by John_Berger, Jul 2, 2002.

  1. John_Berger

    John_Berger Cinematographer

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    The home theater companies never cease to amaze me. Here they are touting how HDTV is going to revolutionize picture quality. Of course, I get a Mitsu 55" 16:9 TV thinking that I can take advantage of, among other things, the higher image quality.

    Yet I (apparently) can only get 480p even over component/progressive scan? I would think that the resolution of a progressive scan DVD could support 1,080.

    Is this another one of those "We don't want to make it too good in order to offset piracy" situations? The TV can be configured for 1080, so I would think that I should be able to take advantage of it.

    What am I missing here, guys?
     
  2. Richard Travale

    Richard Travale Producer

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    This thread covers this topic extensively. It may be quite a bit to wade through but there is a lot of very useful information.
     
  3. Vince Maskeeper

    Vince Maskeeper Producer

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    And you would be wrong.
    Progressive scan DVD is 480p. The DVD format is not a high definition format, so it is native to 480 lines. 1080 DVD is not yet available- and the discussion linked above discusses the possibilities and the future options for such a format.
    It is possible to scale DVD to 1080- but because it's native is only 480 lines (again it is a NTSC format, not a High Def format)-- you won't see a real serious improvement over 480p.
    It seems from your post that you are simply a bit confused on native resolutions of various video formats, and upset with manufacturers because of this confusion. DVD is a NTSC format, meaning it is 480 lines. This is not a case of any corporation trying to screw you out of resolution- rather simply put DVD is a NTSC format and your set is High Def.
    An analogy would be something like: complaining that vinyl Record albums are analog and not digital, and claiming that the RIAA is simply trying to screw you. In actuality, the simple fact is the vinyl record format is just analog.
    -Vince
     
  4. Greg_R

    Greg_R Screenwriter

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  5. Vince Maskeeper

    Vince Maskeeper Producer

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    Certianly- however I guess I should have said more clearly- you can scale DVD but you cannot:
    1) "Add" resolution.
    2) Approach the quality of native 1080 material

    I scale DVD to about 600 lines progressive using HTPC, and it looks better than 480p to me- but does not really add resolution and certainly would be no substitute to a native 1080 signal.

    -Vince
     
  6. Greg_R

    Greg_R Screenwriter

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    Totally agree... I just didn't want someone in the beginner section to think that scaling was a waste of time!
     
  7. Justin Ward

    Justin Ward Supporting Actor

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    Just curious here, is SDTV called 576P in PAL countries? Or do they have the same SDTV/HDTV standards?
     
  8. Drew Eckhardt

    Drew Eckhardt Stunt Coordinator

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    1. You can't add detail, but you can add smoothness that isn't be there with the sampled resolution. The result is sortof a lowpass filtered higher resolution image. In practice, 480p scaled to [email protected] beats a lot of theatrical 35mm presentations presented at similar subtended fields of vision. It's not in the same league as 1080i HD material at 360/270Mbps (I've watched too much HDCAM/HDP on good monitors, but have yet to seriously watch anything of interest in the MPEG encoded ATSC formats).

    2. PAL is an interlaced 625 total line/576 potentially visible (they contain image data, but are outside the "safe" area which all monitors should display) line picture running 50 fields per second. Line doubled, it's 576P. In most digital formats, it's sampled as a 720x576 pixel image. Most PAL telecine is accomplished by speeding up the film 4% (audio may or may not be pitch corrected because many people don't notice the difference) and performing 2:2 pulldown where each frame becomes two fields, with the result being a comb-free interlaced image and judder free image (interlaced or progressive) which flickers for more people.

    Conversely, NTSC is a 525 total/487 potentially visible line system running 59.94 fields per second (yes, the number is wierd). Comressed formats generally drop 7 (which will be off the screen on consumer displays) of these and end up with 480 lines that match up nicely with 8x8 sampling regions. Line doubled, it's 480p. Telecine is run at normal speed, with alternating frames of film becoming 3 and 2 fields respectively. I don't know if there's a speed difference to make the telecine work or if there's an ocassional "dropped" frame as on NTSC time code. Interlaced, this yields coming artifacts. Either way, the pacing is evident on camera pans. It flickers less for some people.

    3. There are non-ATSC HD standards, although I'm not aware of PAL flavors. The most popular is probably Japan's analog 1050 total line NTSC derived system.
     
  9. John_Berger

    John_Berger Cinematographer

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  10. John_Berger

    John_Berger Cinematographer

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  11. Michael Lomker

    Michael Lomker Stunt Coordinator

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    John, if you have a conventional tube TV or a RPTV then it won't do it. Many of the modes that they are mentioning only work with front projectors.

    The HTPC/front projector combination is great. When playing DVD's, the quality of the scaled/doubled image approaches that of expensive stand-alone equipment.
     
  12. John_Berger

    John_Berger Cinematographer

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  13. John_Berger

    John_Berger Cinematographer

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    Rather than bring up a new thread of a similar topic, I decided to ask a related question in this thread. [​IMG]
    I'm actually a bit confused as to why NTSC is the restricting factor here for utilizing the potential for DVD to at least overcome the 480 line restriction.
    Correct me if I'm wrong, but if I get a region-free DVD player, I can buy a DVD from England (PAL) and play it on an NTSC system, correct?
    What's also making me wonder about this is that the DVD authoring software that I use recommends 720x480 for the MPEG-2 files, although it does ask in the beginning whether or not it's a PAL or NTSC format. Neither NTSC nor PAL use this resolution, so something must happen to the files. Does the software downconvert the resolution to the appropriate format before writing or do DVDs actually have the VOBs encoded at 720x480 which the player then downconverts to its appropriate video standard?
    Help me to understand this, guys. One skull full of mush waiting. [​IMG]
     
  14. Jack Briggs

    Jack Briggs Executive Producer

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  15. Vince Maskeeper

    Vince Maskeeper Producer

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    This is a good question- and related to one that came up for debate in a thread in software a while back (regarding EE on the Royal Tenebaums DVD). I assume that if you are encoding a PAL disc- the software will resample the resolution (and the frame rate, don't forget PAL is not 30 fps).

    I know that you cannot simply have the player completely create the output resolution from a given file format- but the question is how far can the player go if given a specific set on information. Again, in the debate presented in software- no real conclusions were made, however some suggestion of how material is actually written to DVD was discussed.

    In the end, I'd have to answer "I'm not 100% sure" on exactly how far the player can go in creating signal from a particular source. I'd say with 99% certainty that the material is stored in proper format for NTSC or PAL native on the disc- however some suggested in the other thread that film was stored 24 frames and pulled to NTSC by the player (which I find highly doubtful).

    -Vince
     
  16. John_Berger

    John_Berger Cinematographer

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  17. Justin Ward

    Justin Ward Supporting Actor

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    Ok guys, admittedly I am quite a newbie when it comes to HT in general. However, I consider myself quite knowlegdeable on video formats.
     
  18. John_Berger

    John_Berger Cinematographer

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  19. Vince Maskeeper

    Vince Maskeeper Producer

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    I don't know where that number came from- but I believe it is incorrect. I can see an obvious difference between 15fps and 30fps, and tests with higher frame rate film has been endorsed by some pretty well known people (If I recall, Ebert was a big champion of a new system which had a really high FPS increase.) I know that 24 frames actually seems pretty lacking on panning- there is a judder inherent in 24 frame material that drives me batty.

    So, I assume we can see improvement well up beyond 30fps.

    -Vince
     
  20. Justin Ward

    Justin Ward Supporting Actor

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    Also, some frame rates look better on some sources. For example a 20fps source(like a somewhat choppy video game) may look good on a TV due to a certain amount of motion blurring making it dificult to percieve individual frames. However, the difference between 20 and 30 fps is quite noticeable on a PC.
    Vince, thanks for sheeding some light on the 29.97 fps aspect in NTSC video. I always thought that maybe AC was actually 59.94hz and not 60hz which would explain the 29.97 fps, but your reasoning seems to make a little more sense.
    Now i am unsure if the video on DVD is stored at 23.976(film) or 29.97/25 fps NTSC/PAL. I think film source DVDs (movies) are stored at 23.976(if not, they are wasting bit rate) and stuff like TV shows(simpsons and x-files box sets) are stored in their native format.


     

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