3 Replies Latest reply on Nov 30, 2009 7:39 AM by Mylenium

    Prerender comp takes forever

    ingvarai Level 1

      I am trying to do speed up AE, to the extent it is possible at all. So I have read me up on several articles covering this topic, among others this.

      My first attempt to speed AE up, is to prerender a composition. It takes forever! The entire project, with several comps, time warp, keylight, masks, 3D layers etc. takes 7 minutes to render - complete. When I try to prerender on of the compositions, the gauge moves at snail speed, and estimated time for the prerender is 1 Hour and 37 minutes..



      Ok, I found the culprit: The Timewarp.

      The comp I try to prerender uses an underlaying comp. This underlaying comp has just one AVI, and this AVI has just one effect added - the Timewarp. When shutting Timewarp off - all runs fast.

      The big $10 000 question now is why the Timewarp slows down prerendering one particular comp - but does not slow down rendering the main project where the comp containing the Timewarp is included!


      Edited - 2:

      I now tried to prerender the comp with TimeWarp only. It is an AVI 960 x 540 pixels, 25 fps. And it has one single affect added - TimeWarp. This needs 24 minutes to render..

      And the whole shebang - all comps, effects, layers (more than 20) takes 7 minutes to render.. Can the layer (comp) in question somehow have been rendered anc cached in the background, while I have been working? I have disk cache turned on. And that AE now is ignoring this cache?

      I need a detective, Poirot or someone with his capacity!


        • 1. Re: Prerender comp takes forever
          Mylenium Most Valuable Participant

          Render order and how the items are related, most certainly. When you render from the main comp, AE would only request the frame it currently needs for temporal sampling. It is smart enough for that. By pre-rendering in combination with your other effects you may somehow trigger a weird loop that forces AE to request multiple frames multiple times based on how it processes the effects stack. Hard to tell without seeing your actual setup. I wouldn't even call it a bug, but it's certainly an unfavorable behavior. The only other option I could think of is that it is not doing any frame-blending when you render from you main comp. You should see that by differences in the resulting clips. In that case some layer switch (continuous rasterization springs to mind) may bypass the Timewarp effect/ disable some of its routines - by design or based on buggy code. i realyl think it's a combination of a few things.



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          • 2. Re: Prerender comp takes forever
            ingvarai Level 1

            I can say so much that the Timewarp effect performs beautifully in the final render, It is one of the first times I have used it, and I am very impressed. I adjust the speed several places, to match one action with another action. At a certain point, Timewarp only has a few frames to stretch over a longer time span, and it does this just beautifully, real convincing slowmo. So it definitely kicks in when doing the final render.

            Anyhows - I do not give it too much thought.

            What I did, I rendered the original clip and accepted  24 minutes to get it done. I then used it in the main comp, and can now preview at full speed.But one and a half hour in a nested comp - as opposed to seven minutes in the final render.. I suspect you are right, AE is working too hard and thinking too much I believe..


            • 3. Re: Prerender comp takes forever
              Mylenium Most Valuable Participant
              AE is working too hard and thinking too much I believe..


              Quite possible that in this case the smart cahcing (to RAM) is working against it. I agree, though, rendering once then working at normal speeds sounds like an acceptable compromise.