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does after effects render only what is absolutely necessary? render efficiency…
hi all,
i’ve tried searching but i’m not sure what i should be searching for.
it seems some of my large comps (am still working at about 8000×8000 base animation then using camera moves in a 1024×576 comp) are taking a REALLY long time. And even though AFX is supposed to be able to cope with comps up to 30 000 x 30 000 pixels, I get out of memory errors / image buffer errors.If i have an 8000×8000 comp, then put this into a 1024×576 comp, does AFX intelligently only render the 1024×576 section of the 8000×8000, or does it render the whole thing, THEN crop it down to 1024etc?
If i had an 8000×8000, going into a 4000×4000, going into a 1000×1000 does it only render the 1k x 1k chunk of each, or does it render the whole of the first, then crop it, then the whole of the second, then crop it?
I’m trying to figure out what I can do to get rid of these image buffer errors. I am pre-rendering nested comps, but at this rate it could take days to end up with a final render. And I’d still end up with many layers of quicktimes comped onto each other.
If I can understand HOW after effects deals with these comps and sizes, maybe it’ll help me figure out how to reduce my render times.
Thanks,
Scott. -
6 Replies
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AE will try to smartly render such things, but there are limits to that for technical and mathematical reasons, the main one being that AE does not have a way to automatically split images into tiles. So in case of your big comps it will always hold the entire image in RAM and do its calculations on it. Your pre-rendering doesn’t really do anything to improve the situation most of the time, I’d say. The only thing that would improve matters, is to split up you large images into “tiles” and then re-assemble them using parenting or expressions. This would AE allow to ignore any tiles that are outside of the visible frame and consume less RAM. Quite obviously there are some downsides to that such as potential blending problems at the seams or effects no longer looking as intended.
Mylenium
[Pour Myl
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One way to get around the out of memory/image buffer errors is to lower your cache down below 50%. I usually run my cache at around 80% but everytime I get the image buffer error when rendering, I lower my cache (after trying the Purge All and whatever else may help, which never does) down to 45% I’m able to render without any problems. It renders a bit slower but I don’t get the crash.
Sean Cusson
Q media design
sean@qmediadesign.ca -
I should add, only lower your cache when the error comes up (when rendering, for example)
Sean Cusson
Q media design
sean@qmediadesign.ca -
… and go into the secret prefs by holding down the shift key when accessing the preferences (release shift when the dialog box appears) then within the secret prefs, setting AE to purge every 5 frames or so during Make Movie. This slows down renders to a degree, but prevents crashing. Your mileage may vary.
Big layers are RAM suckers, and potential comp killers as a result.
Steve
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Without knowing the structure or nature of your comps (fx, 3d/2d, motion blur etc) I can only give a general advice – Collapse Transformations…
Try putting your effects in the last comp in order to avoid rendering fx on the whole image. I don’t know if this makes sense in your workflow, but I think it’s worth mentioning. If it applies to your work you could see significant increases in speed and responsiveness…
Cheers,
Fred -
thanks for the help guys, i suspected afx was holding the whole huge comp in ram, but wasn’t sure. i prerendered quite a few of the layers, which did help, because even though they’re still HUGE, the effects don’t need to be rendered every frame, so much less processing needed. was quite effects intensive – couldn’t collapse because the effects went haywire.
i’d altered the secret prefs before as well in an effort to reduce the number of errors i was getting, but sadly they didn’t help that much. some segments i couldn’t even preview at full res after a purge, let alone render them, so altering the maximum memory usage / flushing the cache every x framers didn’t do much for me.
last night i tried rendering to a tiff sequence rather than a lossless quicktime, and oddly enough, no errors. perhaps because it didn’t have to build a large qt, only individual frames. who knows.
well, the combination of patient pre-rendering and a tiff-sequence worked for me. so if people are getting out of memory or image buffer errors, in addition to all of the above, i recommend trying to render a sequence rather than a quicktime. seems to work.
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