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time remap expression doubling render times?
Thanks in advance for any help/suggestions
THE SHORT VERSION
I have a fairly complex hierarchy of compositions and I duplicated a layer and time remapped each duplicate to start at a different time. So far no problem. But then when I added an expression to the layer’s time remap value to help me automate my process, the expression gave me the desired result along with a very un-desired doubling in my render times. Yet its simply changing the time remap value, how could this make it so much harder to render?
Anyway any tips/suggestions would be great or at least confirmation that I’m not crazy and that expressions themselves in a case like this can really harm render times.
Thanks!
THE LONG VERSION
Let me simplify my situation the best I can. I am making a few scenes that involve close up groups of time lapsed flowers. There are 5 different types of flowers and about 12 different videos of each flower which allows the group to be a unique bunch.
Rather than rendering 60 different videos for each flower of each type (each about 10 seconds) I rendered 5 videos for the 5 flower groups each about 13 minutes.
Then since I want to be able to add a single edge lighting effects to all of the flowers I put all 5 videos into one “all flowers” pre-composition, playing the different flower type videos sequentially. Then I put that “all flowers comp” into a composition and duplicated it about 24 times and arranged it into a bunch I liked. Then I simply time-remapped them to be the different recorded flowers. So far the render/preview times are bearable.
But then thinking I was clever I added an expression to the time remap value on each of these “all flowers” duplicates. I also added a null layer and put a slider on it called “flower type”. Then I wrote an expression that would advance a flower layer’s time remap value by enough time so that it would advance to the next flower type. Eventually I got it to work but then I realized my preview/render times more than doubled. It’s lame!
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3 Replies
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It would help to see the expression.
Dan
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Dan thanks for your help but I think I realized that the increased render times weren’t associated with simply the expression. They were associated with the fact that the expression separated the videos greatly in time. I ended up with the same issue when simply removed the expression and then moved the layers horizontally to separate the times. I guess it’s pretty obvious that AE doesn’t have to work as hard when layers are showing the exact same thing at the same time.
Thanks though.
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It’s the nature of expressions to put a strain on your system, they recalculate their function each frame.
I few years ago I had a very complex project which had over 500 expressions reading text from external documents as well as few conditionals and other simpler stuff. When rendering tests and ram previews everything was fine, so I kept adding expressions over and over.
When I finally was ready to render the whole thing the project would crash every time I tried to start the renders, but it was to late to bake all the expressions. Long story short I used the secret preferences to force the machine to render each frame regardless of anything and even that way it took roughly three weeks to render 9 minutes of video. The render would move a few hundred frames, then stop without making the sheep noise so I ad to manually restart it each time.
Expressions are very useful, but they can become your worst nightmare if you abuse them as I did.
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