9 Replies Latest reply on Mar 2, 2014 5:29 PM by Rick Gerard

    After Effects CC slow renders on iMac (low CPU Usage?)




      i have an fully specced late 2013 27" iMac for working with the Creative Cloud Programms. At the moment i only have 8GB installed because of problems with my 32 GB Ram kit. I have an internal SSD for the OS and Programms, an 256GB USB3 SSD for Chache Files and a Raid 0 for my Source Files.


      I am now rendering an 7min long movie shot on an Red Epic in 5K and 4K to an ProRes422HQ 1080p File out of After Effect. I mainly used the "Levels" Effect and an Plug-In called "Film Convert". No crazy animations or effects. My Render time is about 18 hours (it`s nearly finished, so this are no wrong calculations by AE).


      Are this normal render times that should be expected when working with such large source files?


      What makes me wonder is that the Activity Monitor show only bout 40% CPU Usage (see attached screenshot), shouldn`t that be maxed out?


      AE_CPU USAGE.png


      I have to render out a few more similar clips, so optimizing this would be great.


      Thanks a lot for the help!

        • 1. Re: After Effects CC slow renders on iMac (low CPU Usage?)
          brad.magnus Level 1

          First I'm on a PC, so I can't speak specifically to your OS, but generally speaking when the CPU isn't maxed out then there's another bottleneck elsewhere. For instance I think it's typically seen when the HDD's are slow, the CPU can't work at 100% because the drives are slowing it down. In your case, I wouldn't think it's the HDD's your setup looks great there, so my guess is the RAM, but it could also be the GPU?


          I'm by no means an IT guy, but I just went through a ton of research to do some upgrades to my machine. That's a pretty outrageous render time, hope you get it optimized.

          • 2. Re: After Effects CC slow renders on iMac (low CPU Usage?)
            Rick Gerard Adobe Community Professional & MVP

            There could be a zillion things oging on here. You could have a Ray-traced comp, you could have badly misassigned your memory, your source footage that is clogging up the buss because of conflicts with other codecs, you could have 3rd party apps installed that are preventing AE from running efficiently. Without precise details on your project, your render settings, your output module settings, your source footage, it's impossible to say if the render times are high.


            How much experience do you have with AE? Do you have footage from other sources you can substitute for a test? If you don't just create a simple comp with a gradient and a moving 100 pixel shape layer moving around and render to a fast production codec like ProRez 422 or QuickTime Jpeg and drop that footage in your comp to replace the Red footage and see if the render times drop. Solving problems like this usually requires some detective work. I would start by trashing your prefs and letting AE pick the default memory settings.

            • 3. Re: After Effects CC slow renders on iMac (low CPU Usage?)
              BESRES Level 1



              thanks  a lot for your answers!


              I was too thinking about the HDD setup but i think mine is pretty decent. My source footage is on an 3 HDD Raid-0 with 550 MB/s read and write, i have an 250 GB Scratch/Chache SSD in an USB 3 UASP enclosure thats around 400 MB/s read and write and my project files are on an external USB 2 drive (will change to USB 3 soon). Only thing is that i am outputting my files to the Scratch/Chache SSD right now because i am still waiting for my USB 3 "Output" drive. But i don`t think the Chache is beeing used while rendering, or could that be the mistake?


              The GPU is this one: NVIDIA GeForce GTX 780M 4096 MB and should be ok i think.


              I hope my new 32GB Ram kit arrives soon, so i can test if more RAM helps.



              I have an 4K HD (Quad 1080p) Composition which contains mostly 4K HD source footage mixed with some downscaled 5K HD shots and some upscaled 2K HD Shots. The comp is mainly a simply edit from premiere with a Levels effect on every clip and the 3rd party film convert plugin plus an Unsharp Mask on the whole comp on adjustment layers. I tried turning those off too but it wasn`t speeding up much the rendering. I have no Ray-traced comp.


              I left the Render Settings to "Best Settings" for the final rendering. Altough for preview purposes i was putting the resolution to "quater" in the Render Settings and it took only about 30min for the whole comp to render.


              In the Output Module i was chosing ProRes422HQ as a codec and 1920x1080 as output resolution.



              The 4K and 5K shots are looking pretty good when rendering with the Render Settings turned to "quater" resolution but the 2K shot are looking terrible then. Could the long render time be a problem with how after effects handels the de-bayering of the R3D Files?

              • 4. Re: After Effects CC slow renders on iMac (low CPU Usage?)
                BESRES Level 1

                Ok, i know did some render test in After Effects and Redcine-X but still don`t know why my AE renders are so slow.


                I used an 20 sec. long 5K HD R3D Clip and tried varoius ways in After Effects to export it to an 1080p ProRes 422HQ File. I put the clip in an 5K, an 4K and an 1080p timeline and rendered it out. I also tried to render to an different SSD,putting the source file on my internal SSD, resetting my Preferences and turning off Multicore Processing. Result was that everytime the rendertime was around 11min 30 sec. (plus minus a few seconds) and CPU Usage was similar to the screenshot in my first post( around 42%).


                Then i tried outputting the same file to 1080p ProRes422HQ out of Redcine-X. My first render took 39 sec. and my CPU usage was maxed out! But since Redcine-X can use the GPU for transcoding R3D Files which AE can`t,  i did another render with the GPU rendering switched off to get an fair comparison. This time my CPU Usage was lower then in After Effect (about 38%) but my render time was with 4min 23 sec still much faster than AE.


                What could be my problem here? I don`t think the CPU Usage is that important since Redcine-X can also render much faster without more CPU Usage. Is more RAM making that big difference while rendering?

                • 5. Re: After Effects CC slow renders on iMac (low CPU Usage?)
                  brad.magnus Level 1

                  That's very interesting! Honestly, that's a little out of my depth, as I don't work with 4k or 5k footage. The only thing that I noticed out of your comment is the GPU usage and Ae. Did you try rendering with Media Encoder? In general, I've found it to be slower than Ae, but it does have the option to use the Mercury Playback engine GPU at the bottom. Just a thought. I do hope you get it dialed in, cause there's nothing worse than waiting for a render to finish

                  • 6. Re: After Effects CC slow renders on iMac (low CPU Usage?)
                    BESRES Level 1

                    Thanks Brad, i hope i will find some solution for this too, would be great not waiting that long for the rendering to finish!


                    I now tried rendering 20 sec of the final comp that i am working on instead of the 20sec test clip. It was a section with about 9 cutted 4K HD Clips and i disabled all effects and adjustment layers. Interestinlgly it took about 21min to render. Compared to the 11min for the single test clip that`s quite a lot for some simple cuts.


                    I also tried rendering the same part of the comp with the Adobe Media Encoder but it took even longer, nearly 38min. I also think the GPU engine is not working for transcoding Red Material since Red has not published an SDK for it yet. At the moment only Redcine-X supports that as far as i know.


                    Any other ideas?:)

                    • 7. Re: After Effects CC slow renders on iMac (low CPU Usage?)
                      Rick Gerard Adobe Community Professional & MVP

                      I would think that the best workflow would be to transcode your Red footage to a production codec for processing. That's the workflow I use for most footage from most professional cameras and for about 99% of footage from pro-sumer or consumer cameras.

                      • 8. Re: After Effects CC slow renders on iMac (low CPU Usage?)
                        BESRES Level 1

                        I was thinking about this too since rendering in Redcine-X is so fast but to me it just seems like an unneccesary step that i would like to avoid if anyhow possible.


                        I now did an render of the same 20 sec timeline piece in Premiere CC and it was much faster than in AE. About 5 min using best quality rendering and much shorter without it. Also my CPU was maxed out during the rendering in Premiere, so i really think this is just some issue with my After Effects setup.

                        • 9. Re: After Effects CC slow renders on iMac (low CPU Usage?)
                          Rick Gerard Adobe Community Professional & MVP

                          Tell you what, post 100 frames of red foottage and I'll try some test renders on my machines and let you know what I see.