I thought 3/2 pulldown was handled by dvd player?

Discussion in 'Archived Threads 2001-2004' started by Jeff Adams, Dec 18, 2001.

  1. Jeff Adams

    Jeff Adams Screenwriter

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    I am a little confused by this. I thought the 3/2 pulldown for film based materials was handled by your dvd player. I have seen seen HDTV'S advertising that they do 3/2 pull down. What does what? Is it better to have both the tv and dvd player doind 3/2 pulldown?
     
  2. Robert George

    Robert George Screenwriter

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    3:2 pulldown detection is a function of a deinterlacer. This is done when standard interlaced video material is converted to a progressive scan signal.

    Progressive scan DVD players have a built-in deinterlacer so the 3:2 pulldown detection is done there and a 480P signal is sent to the monitor. It is desirable to have 3:2 pullsown detection in a deinterlacer in the monitor as well for any other video inputs that are from other sources. BTW, any 480P or other progressive formatted signal input into a HD-compatible monitor bypasses the internal deinterlacer.
     
  3. David X

    David X Stunt Coordinator

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    Well, I'm no expert and hopefully somebody here will correct me of I get it wrong but as I understand it ... if you have a progressive scan dvd player then the dvd player should handle the 3:2 pulldown.

    If not, and your monitor does it, then the monitor will handle it.

    Only one device can handle this, not both. In most cases, as I understand it, a decent progressive scan dvd player usually does a better job of it than a typical monitor.

    I guess the benefit of having this feature in the monitor is for use with existing (non-progressive) sources that don't do 3:2 pulldown. In that case, there's probably some advantage in having the monitor de-interlace the source when it can figure out that the source is 'film' and have it do the right thing with the extra frames that it sees from an interlaced source.

    -David
     
  4. David X

    David X Stunt Coordinator

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    oops .. robert posted his reply as I was typing mine.
     
  5. Jeff O.

    Jeff O. Stunt Coordinator

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    Robert,
    I am curious as to your statement
    "any 480P or other progressive formatted signal input into a HD-compatible monitor bypasses the internal deinterlacer"
    I am pretty ignorant when it comes to video and am trying to understand all of this. According to this thread:
    http://www.hometheaterforum.com/htfo...threadid=29706
    the Toshibas and Hitachis upconvert everything to 540p. Does this mean that it has to be deinterlaced to be upconverted? (I guess it isn't if it is progressive already it can't be interlaced). But if the set also does 3:2 pulldown, then it would be done twice? Or, since it isn't deinterlaced, just upconverted, there would be no 3:2 pulldown in the set. I hope this isn't too confusing, but do I have the general idea?
     
  6. Jeff Adams

    Jeff Adams Screenwriter

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    Well Jeff O, let me see if I can get this right. And you know why I posted this thread? Because of the coversation we were having about the Toshiba. Got me curious so I went to Toshiba's web site. Anyway. The way I understand it is if any source is an interlaced signal and your tv is able to upconvert it to 540p then that is when the tv does it's enhancing. If you are feeding the monitor a 480p signal then it will bypass the monitor's enhancement and give you a pure progressive scan picture. In that case you will get to enjoy the benefits of progressive scan and anamorphic dvd's.
     
  7. Jeff O.

    Jeff O. Stunt Coordinator

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    Jeff,

    Yes, I think I know why you started this thread. The reason that I said that Toshs upconvert even 480 progressive signals is from the statement by Michael TLV (or something like that) in the thread that I indicated above. Where on the Toshiba site did you find the information that a 480p signal is passed natively? If that is the case I would like to know. I didn't find much useful information on their site.

    Thanks
     
  8. StaceyS

    StaceyS Stunt Coordinator

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    A couple of points.
    3-2 pulldown is the process of converting 24fps film into 60 field per second video. All DVD players do this, including the interlaced ones.
    3-2 pulldown detection, as Robert mentioned, is the process of detecting the original 24 fps in a 60 field per second stream, and displaying them in an optimum way.
    The Toshiba TVs will first deinterlace 480i to 480p, and then they will scale the 480p to 540p. If you feed them 480p, they simply scale 480p to 540p.
    A TV capable of progressive scan must have a deinterlacer built-in for all other sources. It is cheaper to make a TV run at 480p only vs. 480i and 480p. A TV that has 3-2 pulldown detection built-in will benefit non DVD sources like LD, DSS, cable, etc.
    Do you want to use deinterlacer in TV or 480p DVD player? It all depends on which ones does better deinterlacing. Kind of like the debate on which output of a LD player should you use, composite or YC. (in that case, which ever had the better YC separator.)
    sorry for any spelling errors, I am in a hurry today. [​IMG]
     
  9. Jeff O.

    Jeff O. Stunt Coordinator

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    Thanks Stacey, that makes sense. So with the Toshibas, the question would be whether to feed the TV the 480p from a DVD player (in which case the DVD player would do the deinterlacing), or a 480i (non-progressive) output from the DVD player and let the TV do the deinterlacing. In either case, the TV would upconvert the 480p signal to 540p. Hopefully I have this correct now.

    And to add, whether you would get a better picture on a Toshiba with a progressive DVD player would depend on whether the deinterlacer was better in the DVD player than in the TV.
     
  10. Jeff Adams

    Jeff Adams Screenwriter

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    This is all pretty confusing stuff. All I know is I have a progressive dvd player and an hdtv and the picture looks sooooo much better than my non progressive scan unit. I'm happy![​IMG]
     
  11. Dustin B

    Dustin B Producer

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    One other thing to consider. The DVD player has the picture in digital format to begin with. The monitor has to convert an analog signal back to digital so it can deinterlace it, then convert it back to analog to display it. It's almost always better to do the former. Conversions between analog and digital will invariably introduce image artifacts. How noticable they are will depend on the viewer and the quality of the ADC/DAC of the monitor.
     
  12. StaceyS

    StaceyS Stunt Coordinator

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    Thanks Dustin, I forgot to mention that. Now, the new Tosh may A/D everything if it only displays 540p.

    DVD players have an advantage. Two fields will be bit-for-bit identical. However, once converted to analog, noise will be introduced into the image. The duplicate fields will no longer be 100% identical, so it will make it just a little harder on the deinterlacing engine.
     
  13. LarrySkelly

    LarrySkelly Stunt Coordinator

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    Also, if I recall from reading some material earlier this year, to do the best job at line doubling you need to examine the frame flags present in the stream of digital frames. This information is obviously long gone by the time the analog stream reaches the monitor.

    And you need to buffer a number of successive frames. I imagine (but I'm guessing) that along with 'noisy' data, an analog line doubling algorithm has fewer successive 'frames' to work with. But I have to say, the Pioneer Elites do a credible job at doubling the analog signal.
     
  14. Rick Radford

    Rick Radford Supporting Actor

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  15. Jeff O.

    Jeff O. Stunt Coordinator

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    Dustin,

    Just to make sure that I understand. The signal output from the DVD player, whether progressive or interlaced, will always be analog. Therefore, if you use the progressive output (D/A conversion done in the DVD player) the set would not have to do the A/D conversion to convert it from 480 to 540p. If you use the interlaced output, the DVD player does the D/A conversion to output the analog signal, that is then converted back to digital (A/D) in the TV to do the deinterlacing and upconversion and then converted back to analog (D/A) to output the final image. Is this correct, or does the TV also have to do a A/D and D/A conversion on the progressive signal to upconvert it from 480 to 540p?

    Sorry to be so dense.
     
  16. Dustin B

    Dustin B Producer

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    Yes that is correct. But from what I've read here from others, that is only true on a Toshiba set. Any monitor that will display 480p and doesn't upconvert to 540p will not need to do an A/D D/A conversion if hooked up to a progressive scan dvd player.
     

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