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Scaling a video layer
I notice that if I import a video clip into an AE comp set at740x486 DV NSC, if I scale the video up a bit, say at 105%, the result after rendering is I get some funkyjagged lines in the video (this happen to be action video … football)
Is there a way to correct this or must the video be set at 100%?
Thanks all!
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3 Replies
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That’s probably because the footage is interlaced.
In broadcast and DV, frames are usually split in 2, so that half of one frame is shown with half of the next or previous frame. It’s split by showing every other line of current frame mixed with every other line of the other frame.
When AE imports footage, it interpretes it and deinterlaces it, so every other line is removed. If you scale it up, you end up with some bad artifacts. There’s no perfect way around this, but this might be worth posting for advice in the main AE forum. There are plug-ins that can help you work around this issue.
Or you might try to render the footage at 100% out of AE and make sure to have interlacing turned off. Then reimport it – i t may look better and give you the ability to scale without artifacts.
No promises – this is a tricky area.
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Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
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Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com -
Also want to say – if anyone knows better than me (and I;m sure some of you do) please chime in. I avoi interlaced footage when possible, and when not, I rarely scale it.
—————————————-
Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
—————————————-
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com -
[mikeab00] “Is there a way to correct this or must the video be set at 100%?”
This is a 2-part solution to your problem, and it depends on the codecs you are using.
First, you have to “interpret” the incoming clips correctly, telling the system what field order the clip has (which lines are forming the first field and which ones the second). To do that, select your footage in the Project window, right-click them and select “Interpret Footage”. There you will see a selection for “Separate Fields” where you can choose “upper field first”, “Lower field first” or “Off”. Most NTSC footage is lower field first, but it depends on the codec you are using.
If your footage is interpreted correctly you also have to render in fields back into your codec. When having set up the render in the render Queue, make sure that in “Render Settings” Field rendering is also set to the correct field order. Then you should get correct rendered interlaced footage.
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