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Can film sourced 480i be simply scaled to 1080i?

421 Views 3 Replies 3 Participants Last post by  Allan Jayne
Hey all you gurus out there. :)


I recently got the HD-A1 and I'm certain the picture looks best for regular DVD output at 1080i over HDMI to my NEC 50XR5. The other options via HDMI are 480p and 720p I have the player in "film" mode and the NEC in "Cinema" mode for 1080i to activate 1080i IVT.


I've never been a big believer in the benefits of upconversion per se. At first, I assumed the player was likely just scaling 480i->1080i and my display was performing IVT but a knowledgeable person pointed out to me that that wasn't likely the case and I tend to agree.

I'd say the likely steps in the player are 480i->IVT->480p24->1080p24->telecine->1080i before output to the display. Assuming this is correct and 480i can't be simply scaled to 1080i with the 3:2 cadence intact why would I see a better image?


Or am I just imagining it? :)
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If the image looks better to you, then it is better, right?


My 2 cents
Of course. I'd like to know why though.
You will not get good results scaling individual 480i fields to become 1080i fields. If you did, the result (on a 1080i CRT TV) would have scan lines out of order, as:


1

. 2

1

. 2

3

. 4

3

. 4

...


479

, 480

479

, 480


The correct processing is 480i to 480p to 540p content 1080i and then optionally using filtering and/or diagonal enhancement to 1080i content 1080i. The 1080i content 1080i is called that because all 1080i scan lines can be unique, but when the source is ordinary DVD, the source detail is still at most 480 lines ov resolution vertically.


Whether the 480p step for film source is 24 fps or 60 fps depends on the exact processing used. If the 480p is 24 fps it will be immediately converted back to 60 fps by re-imparting 3-2 pulldown, in order to generate 1080i. If the 480p is 60 fps, the same 3-2 pulldown originally in the 480i will carry through to the 1080i.


Video hints:
http://members.aol.com/ajaynejr/viddoubl.htm
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