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Reversing field order / dominance

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Martin Fisher
Reversing field order / dominance
on Jul 28, 2010 at 11:54:56 am

Hi there,
Hope that someone can clarify this ASAP (as i have to render things tonight for deliver them tomorrow)

I need to reverse the field order of a footage that im working with. This footage was shot on XDCAM. Its HD (1920x1080) 29.97 fps Upper field first. This needs to be outputed on a DigiBetacam NTSC (720x480) 29.97 Lower field first.

1.So, the editor send me a QuickTime movie in 1920x1080.
2.I separate fields (Upper) in "Interpret footage".
3.I make some graphic, color correct, move and scaled it, etc.
4.I make a NTSC D1 composition
5.I Drag the HD Comp into the SD Comp and fit it to Heigh.
6.I render using Upper field first.


As i mention before, the render should be Lower field first.
So i wonder what would be the correct way to reverse it.

Maybe if i take that render and move it one pixel up (or down) and then render it again ? (Without sepparating fields, and whithout choosing a field dominance in the render settings ?)

Any help will be much appreciated

Thanks


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Michael Szalapski
Re: Reversing field order / dominance
on Jul 28, 2010 at 1:16:27 pm

You're downconverting HD to SD, so you're going to be losing the HD fields in the loss of resolution anyway. I would say do what you did originally, except render out lower field first.

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Dave LaRonde
Re: Reversing field order / dominance
on Jul 28, 2010 at 3:06:57 pm

[Martin Fisher] "Its HD (1920x1080) 29.97 fps Upper field first. This needs to be outputed on a DigiBetacam NTSC (720x480) 29.97 Lower field first.... I make a NTSC D1 composition...."

Why on earth are you doing THAT? The resolution on the D1 Comp Preset is 720x486, not 720x480! You need to use the NTSC DV Comp Preset, which has the proper resolution... and you can use any codec you want for rendering. Furthermore, you should RENDER using the AE Render Queue and you should NOT export.

If you interpret the HD footage as upper field first -- which is what it is -- and you render lower field first -- which is the proper field order for that resolution -- you will be just fine. AE knows what it's doing with field order.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Martin Fisher
Re: Reversing field order / dominance
on Jul 28, 2010 at 3:59:55 pm

ops ! the 720x480 was a mistake... im using 720x486.

same thing with the export thing. i dont think i ever used the export function.

sorry about those.

and thank you both for the help !

m.


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Dave LaRonde
Re: Reversing field order / dominance
on Jul 28, 2010 at 4:14:12 pm

Just so you know, the field order for NTSC D1 is the same as NTSC DV -- lower field first. That's the field order you render.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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