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Dumb question: What's 3:2 pulldown?  

post #1 of 5
Thread Starter 
I should know the answer to this but I don't. Would appreciate an explanation in basic terms. What is it, why is it important, how do you provide for it?

Thanks.

Dan
post #2 of 5
The link provides a good explanation. Also the May issue of Home Theater magazine has a very good article on Progressive scan DVD players, and details what make a DVD player a progressive scan and what doesn't. This topic relates to 3:2 pulldown and gives a good working explanation of this topic.

http://www.puffindesigns.com/support...apers/3-2.html

Hope this helps.

T

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Todd
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post #3 of 5
Here's another one that may be of some help.

cd

http://www.dvdfile.com/news/special_...2_pulldown.htm
post #4 of 5
Try this link as well, it explains 3-2, and compares progressive DVD:
http://www.hometheaterhifi.com/volum...e-10-2000.html

Two good DVD to watch for the 3-2 effect:

1. Super Speedway, Ch. 7 stadium scene, Ch. 21, also stadium
2. Titanic DVD, eveytime Titanic shows up, lots of diagonal lines and movement, this is where 3-2 effect is most easily seen.

If you are trained to see this effect, you can spot it easily on all movies with moving scenes (not quick motion, but panning the camera). Other good DVDs incluse Haunting and Armageddon.

Once you saw the DVD demo, visit the link again, then you'll understand what 3-2 is, and why it is important on big screen.

So, when people judge a scaler inside a projector, there are two things to watch:
1. Video processing, does it have reversed 3-2? does it handle 2-2?
2. Scaling, after progressive processing a 480i to 480p, then the scaling is in to scale the image to fit the panel.

LP350 is said to have a good scaler, becuase it uses Genesis VLX-1A, it's both a reversed 3-2 processing and a scaler, that's why people are impressed with it. But it does not handle 2-2, see the above link, it has a good comparison of Genesis chip to DVDO chip.

Most projectors uses scaler other than VLX-1A, hence they handle movies poorly, that's why an iSan is recommended since it has a good DVDO chip, but iScan just process the signal to 480p, it's the projector's internal scaler to scale up to, say, XGA panel. The scaling can have artifacts, even fed by a perfect 480p signal from iScan.

So, you might ask, what's the best projector? Well, I havn't seen one yet, the ideal one maybe using a DVDO chip, and feed the 480p signal in digital form directly into a good scaler. When people uses HTPC, the signal is extracted from the DVD in its progressive form 480p, then use the super high end graphic scaler like GeForce 256 to scale it, still in digital domain, to the projector native resolution. NOW, that's the best existing solution, and that's why many people of this forum is using HTPC.

Tzung-I
post #5 of 5
Thread Starter 
Well, once again the incredible knowledge base of this group is demonstrated. Thank you, gentlemen for the great links and explanations.

Bottom line, I think, is that one should pretty much plan on the need for an external scaler/processor with any of the projectors currently out there. Although, it does appear some progressive scan DVD player/projector combos will also perform well. Is this a correct assessment of the situation?

Certainly, any vendor who is working on a new/upgraded projector has the opportunity to remove this deficiency. Let us all hope someone does soon.

Dan
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