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I was reading a review (by Gary Merson) on the Panasonic CT-34WX50 television set. When talking about the built-in line doubler, he mentions that it has no 3/2 pulldown. However, he says that the latest Panasonic DirecTV set-top box, has 3/2 pulldown when upconverting.


I am curious about a few things:


1) Do any other boxes (DTC-100, DST-3000, etc.) have this 3/2 pulldown when upconverting?


2) Just how noticeable would the difference with/without it be (on the size screen of the 34WX50), if you are watching DirecTV, cable, or broadcast TV?


Thanks in advance for any info.
 

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3/2 pull down is a very mis-understood issue. It is a trick used to convert 24 frame film rate imto 30 frame television. In europe they have 25 frame television so they simply run al their TV film material 4% faster.


Anything you watch at home must have 3/2 pull down added or some derivitive of it. You could not watch 24 frames per second as it would flicker. Even a movie theatre shows 48 frames since the falksh each film frame twice.


Where 3/2 pull down comes into play in line doublers and has to do with interlace. The line doubler isn't really doubling the lines, it's taking the two interlaced fields, storing one for 1/60th of a second and outputting the de-interlaced all at once but showing it twice just as a movie projector does. For this to work correctly meaning re-create a true progressive film frame, the 3/2 pull down insewrted in the transfer process must be precisely removed. Otherwise you may get a frame with a field from two different film frames which will just reduce resolution since it goes by so fast.


To spite calimes by various consumer electronics manufactures, this is not an exact process. The processing device must analyze at least two fields and judge if they in fact are the same picture. All television capture devices are analog, yes a CCD is an analog device. With that comes random noise, what may be different even though it's the same picture. So the 3/2 detector must be weighted to ignore small differences such as noise. But in real life there may not be that much difference between two film frames in 1/24th of a second, consider a still shot. So the 3/2 detector is once again fooled.


So how do broadcast convertors do it so well. They don't look at the video at all. Broadcast tape machines record an old fashioned analog signal known as time code. It's a frame count with very simple digital coding. The line doubler simply counts the frames and knows the 3/2 cadance to spite what the image is doing. But that can be upset as well by sloppy editing.


So 3/2 removal is not perfect on any system. To spite the errors, you are better off with a TV or STB that does it versus one that does not.


Glimmie
 
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