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Progressive Scanning Explained

Discussion in 'Televisions' started by Oriphus, Mar 4, 2004.

  1. alseides

    alseides Guest

    Just thought I would add to the PS2 post. The newly (well, kinda new) released version of the PS2 v50000 has some new features:

    Added Progressive Scan video out
    New DVD Player firmware 3.0
    New Remote Control support: Power on/off and tray open/close button
    30% more silent compared to older models
    Support of DVD-R/RW/+R/+RW media

    What you are probably intersted in the the p-scan output. I think that previous models did not support pscan. But this one does.
     
  2. Oriphus

    Oriphus Senior member

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    The flaggin system is quite simple. A set of structured commands that a DVD player picks up on. Why its needed i have no idea and the technical aspect of what it does i have no idea, but apparently it does exist and thats as much as i know ;-)

    Chris
     
  3. vurbal

    vurbal Administrator Staff Member

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    Since DVD is designed to be viewable on an interlaced TV, the video has to be stored in that format. Depending on the source, however, it's sometimes possible to use something called pulldown to convert progressive to interlaced without changing the original stream. The most common (at least in NTSC land) is 3:2 (AKA 2:3) pulldown. You'll also see this referred to as telecined and the process of deinterlacing it as inverse telecine (or IVTC). This involves adding flags to a 23.976p video stream to make it read as a 59.94i (AKA 29.97i) stream. The video still has it's original information, but when it's read by the player, 4 frames become 10 fields (5 frames).

    Let's say you're looking at 4 (23.976p) frames from your original stream (we'll call them F1, F2, F3, F4). The interlaced stream that's actually read looks like this:

    | F1 | F1 | F2 | F3 | F4 | Field 1

    | F1 | F2 | F3 | F3 | F4 | Field 2

    Notice that all then information is still there, so a deinterlacer can theoretically recover the progressive frames.

    There are also different ways to deinterlace 3:2 pulldown material. Some deinterlacers only read flags. Unfortunately, since not all film material is actually telecined (some is actually encoded at 59.94i in the telecine pattern), just following flags won't always work. Another method is to just compare fields for matches to find the pulldown pattern. If it's a close enough match, the deinterlacer will then recover the progressive frames based on that. This gets particularly tricky when you deal with a lot of TV material, since it's common to have the original footage shot on film and any effects, titles, etc., ... done in video. That gives you a hybrid stream that has both telecined film and NTSC video parts. Since real interlacing has different requirements for deinterlacing than telecined film does, that can cause the video to not display correctly, particularly during transitions between the film and video. Then it can get really ugly when a hybrid source is transferred to PAL, but that's another issue (and beyond me to explain in a way anyone could understand it).

    The other type of pulldown (that I'm aware of anyway) is 2:2 pulldown. Like 3:2 pulldown, the name denotes a pattern of fields. For 3:2 pulldown it's an alternating pattern of 3 fields from one progressive frame followed by 2 from the next progressive frame. In the case of 2:2 pulldown it's 2 fields from the first frame followed by 2 from the second. Basically that just means it's actually progressive, but since it already displays at the same fps as the video format being used, it can just be split into fields and displayed as is. That also means that when you want to deinterlace it you can just put the fields back together without having to do any fancy calculations.

    I've never seen any 2:2 pulldown, but I believe it's more of a PAL thing. Basically, if you speed up a film to 25p (instead of slowing it down to 23.976p like in NTSC) you can turn it into interlaced content without doing anything. Obviously 2:2 pulldown doesn't actually require any flags, since the video would look exactly the same with or without them.

    Edit: I just noticed that a lot of the pulldown information was in the original post. Maybe if I'd re-read it I'd have saved 15 minutes of typing.
    _X_X_X_X_X_[small]Backup A DVD With DVD Rebuilder & CCE Basic: http://www.afterdawn.com/guides/archive/dvd_rebuilder_tutorial.cfm
    Good Guides To Get You Started: http://www.chrismccann.co.uk/user_guides.htm
    RTFM - not just a good idea, it's the law![/small]
     
    Last edited: May 1, 2004
  4. Oriphus

    Oriphus Senior member

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    lol - indeed, Pull-down has been explained, but the flagging information was very informative Vurbal, cheers ;-)
     
  5. vurbal

    vurbal Administrator Staff Member

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    No problem. Always happy to show off... err uh help.
     
  6. Oriphus

    Oriphus Senior member

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    lol - showing/helping - its all good when u get the point across ;-)
     
  7. liquid51

    liquid51 Regular member

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    hey, here's question specifically related to the xbox's progressive scanning.
    It can output a progressive scan signal while playing games, but not while playing movies. What with the, ah, "upgradability" of the xbox, it would seem there might be a way to integrate the progressive scanning capabilities to include the dvd playback portion of the box. Or are these things entirely firmware controlled? Or do I have no earthly clue what I'm saying? gotta be one of those ;)
     
  8. Oriphus

    Oriphus Senior member

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    Hi, Im afraid i dont know anything about how the Xbox uses Progressive scanning. I cant think why it only plays Games as progressive scanning (though i know why this would be a good feature). The only thing that comes to mind is that if you are in the UK, some Progressive scanning DVD players only play back NTSC format in Progressive, so maybe you are playing PAL discs?
     
  9. liquid51

    liquid51 Regular member

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    good try, but no, I'm in the states; ntsc.
    I guess the best thing for me to do would be to get a tv that can detect the signal and auto switch between progressive and interlaced. As it is, being one of the less expensive HD monitors (still cost me a grand 2.5 years ago, and it's only 27"!), the dvd and dtv video source options share the same component input, but dvd is interlaced and dtv is progressive, so I have to flop back and forth. oh well, can't have it all :p
    Thanks for the reply though.
     
  10. vurbal

    vurbal Administrator Staff Member

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    This is just a guess, but my thought is that it has to do with the fact that the Xbox is just a PC. With a game you are using PC hardware to run PC derivative software. Like your PC, the video signal is probably natively progressive, and then has to be converted to interlaced. In other words, no deinterlacing involved. NTSC video on a DVD, whether it starts as 23.976 progressive or 29.97 Interlaced, always at least appears interlaced to a DVD player. If there's no deinterlacing hardware required to output progressive for games, it makes sense that they wouldn't bother putting one in just for video.
    _X_X_X_X_X_[small]Backup A DVD With DVD Rebuilder & CCE Basic: http://www.afterdawn.com/guides/archive/dvd_rebuilder_tutorial.cfm
    Good Guides To Get You Started: http://www.chrismccann.co.uk/user_guides.htm
    RTFM - not just a good idea, it's the law![/small]
     
    Last edited: May 14, 2004
  11. liquid51

    liquid51 Regular member

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    that makes sense too. in fact, that would explain why some games don't support progressive scan. They're natively interlaced. hmm.
    Thanks for the help.
     
  12. vurbal

    vurbal Administrator Staff Member

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    No Problem. ;)
     
  13. pek_hui

    pek_hui Member

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    My philips 43" projection tv supports progressive scan (stated in the manual) and i tried hooking up my PS2 to it and started up a game that supported progressive output. The game displays without flickering on my screen...however, my screen is split into 2 (much like a picture in picture placed side by side) and both 'screens' are displaying the same pictures. There's are actual lines (colored...not sure if its blue or purple or green) separating the two 'screens'. Does this mean my TV does not support progressive scan or something wrong with the ps2 or rather, some setting that needed adjusting? I'm not too sure, since I do not have a dvd player that supports progressive output that I can use to see if the TV supports progressive scan or not. Thanks for your help!
     
  14. liquid51

    liquid51 Regular member

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    that is exactly what mine displays when dvd input is selected. I have to switch to dtv input for progressive scan. Maybe you need to switch inputs, or something like that.
     
  15. pek_hui

    pek_hui Member

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    i'm not sure how you go about doing tat...I've clicked around the channels as well as the tv settings, but not sure how to do that...any ideas or specific steps? Its a new tv and i've no idea really how to operate it..
     
  16. liquid51

    liquid51 Regular member

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    well, with mine it's simply a switch of the input source. Perhaps yours requires the progressive scan to be enabled in some way. Not auto detecting. I'm no expert on every hdtv/monitor out there, I'm just guessing. Read up on the manual. It'll be somewhere in there for sure.
     
  17. spike1

    spike1 Member

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    Is it right for me to assume that a prog scan signal is actually duplicated FULL frames??

    I.E Film is actually 48Hz etc????
     

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