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flash frame in Keylight??
I have a really odd problem.
I am using Keylight to key out a greenscreen on several shots. (talking head interview, not a lot of motion.)
When I RAM preview or render out a composition (and this is happening with several different comps, using different pieces of source footage and plates) the background seems to flash at random intervals. It’s usually a frame or two at a time, usually within the first 10 frames of the clip. It looks as though someone applied a brightness filter to the background and cranked it up a stop or so. The foreground is doesn’t change at all.
I’ve tried Edit>Purge All, restarted a dozen times, etc…
Any idea why this might be happening? I looked carefully at the source footage of both the interview and the plate, and there are no signs of anything weird.
The only potential problem could be that the plate footage is ProResHQ and the chroma-keyed footage (foreground) is 8bit uncompressed. Any chance that’s causing this?
System: AE CS3, MacPro 8-core 3Ghz, 11GB RAM, Maxx Digital evoHD RAID array.
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Jason Mann
Compass Light, Inc. -
7 Replies
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some thoughts..
It’s possible that partway into the key, there’s a transparency issue that messes up the background. Watch for any changes in the b/w matte as you scrub. Also, try this noise fix for keylight.
https://forums.creativecow.net/thread/2/931091#931104
or even try precomposing the key then add background. -
Unfortunately I’m still having the same issue. Precomping didn’t help, nor did using a different clip entirely for the plate.
Some interesting facts:
This is happening on three different clips. On one, it happens at 6 frames. On another at 0:11. On the third, at 1:06. And that doesn’t change if I alter the plate/background footage.
One would assume that there is something weird in the keyed footage at those timecodes, but for the life of me, I can’t figure out what it is. There’s nothing visibly different about the matte at those times, either in screen matte view, status view, or in the raw footage.
ARGH. Did I mention these shots are supposed to be done today?
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Jason Mann
Compass Light, Inc. -
Aaaand as soon as I posted that, I have a change to note:
I added new background layers (a new solid layer, opacity 0%, also changed the Keylight setting and added a new instance.)
Noe the same thing happens, but this time it’s on frame 22 instead of frame 30. This is infuriating.
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Jason Mann
Compass Light, Inc. -
Weird, if you would say the key footage is prores…
why don’t you export the footage in another (more) AE-friendly format?
animation ore none…
Just a wild guess, but it does sound like a compression problem. -
Thanks – that’s a good idea. I’ll try animation I guess.
does AE like Animation more than 8 or 10bit Uncompressed. (We tend to capture via our Kona Lhe card using either ProRes, or uncompressed.)
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Jason Mann
Compass Light, Inc. -
AE seems to like QT standard codecs (frame based) more than modern FCP codecs
Normaly you won’t have problems though, only in some very specific circomstances, like keying.. -
Same thing happens to me all the time. Even talked to the Keylight people to try to figure it out.
It has to do with the openGL settings. If you turn it all off everything should render and preview fine.
I have also had some problems with HD footage from Final Cut using the ProRes or DVCPRO HD codecs doing the same thing (flashes).
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