11 Replies Latest reply on Oct 7, 2012 8:23 PM by Rick Gerard

    choppy animation RAM preview & rendered

    rahajav2012 Level 1



      I'm using After Effects CS5.5 Version


      i'm working on an iMac 2.66 GHz Intel Core i5 -- 8 GB RAM, OXS Version 10.7.4.


      i'm creating a fairly simple animation in After Effects, manipulating the position and scale of a still image. i've imported a JPEG i created in Photoshop. my problem is that i have to start zoomed in quite far on a detail of the image, and then zoom out all the way so i need to keep it pretty hi-res in order to have a decent quality when scaled at 150%….the smallest file size/resolution i've tried that has not gotten pixelated at full size is a JPEG 4667x3121 pixels @ 200 dpi resulting in a file size 1.4 MB


      but the animation is still jumpy and choppy -- both in RAM preview as well as when rendered.


      not sure if it makes a difference or not, but i have motion blur turned on


      any help would be appreciated -- how can i make the smoothest animation possible?


      is it exporting the still image in a different format or size or does it have to do with something i'm doing inside After Effects?


      thank you

        • 1. Re: choppy animation RAM preview & rendered
          Rick Gerard Adobe Community Professional & MVP

          The DPI (actually PPI) has nothing to do with video or the web. It's only function is in the scanning world or in print. We just deal in pixels. 1920 X 1080 at 9999ppi is exactly the same as 1920 X 1080 pixels at 1 PPI unless you put it in a publishing app and send it to a printer. Just for fun download these two images and open them in Photoshop, then put them in a Word Doc or place them in Illustrator. Don't drag from the web page, but save the file and then insert into word or place in illustrator. One you won't be able to see, the other will fill the page. You will quickly learn what PPI means.





          Regarding your technique, scale to 150% and you're interpreting 1.5 pixels for every actual pixel so there's going to be some softening. I try and design all of my projects so that I'm never more than 100% on a static raster (pixels) image. 150% is pushing the limit.


          Jumpy or choppy can be a function of stroboscopic effects due to motion and frame rate. If that's the problem then there's only one solution if you're going to keep the same speed - hide the juddering with motion blur. If you can change the speed then that's a better option. There are critical speeds where detail will stutter. There's no way around these critical speeds except blur. The more detail (edges) you have in an image the more noticeable the problem is.


          The other thing that can cause stuttering playback is rendering to a production instead of a delivery codec. AE's default for rendering is Uncompressed. These renders will not playback smoothly. They can't on a normal system because the data rate is just too high. Stuttering in Ram Preview can also be a function of data rate. If you have the Info Panel open you should get a report when frames are dropped.

          • 2. Re: choppy animation RAM preview & rendered
            rahajav2012 Level 1

            thanks so much for your quick reply!


            very helpful. i'm experimenting now with motion blur and keyframe interpolation


            thanks again

            • 3. Re: choppy animation RAM preview & rendered
              rahajav2012 Level 1

              is there a way to add more motion blur to the parts that are extra stuttery?


              i've tried to make the speed of the movement all the same and i've tried

              * turning on the motion blur button...

              * adding Timewarp effect with Motion blur

              * adding CC Force Motion Blur


              still fairly stuttery. to be honest, i don't really "see" the difference any of the motion blur effects make to the layer. what can i be doing wrong?



              • 4. Re: choppy animation RAM preview & rendered
                Rick Gerard Adobe Community Professional & MVP

                We need to know a lot more about your project. A screenshot would help. What is choppy? What are your render settings. Are you using Ram Preview or trying to play the animation using the space bar?

                • 5. Re: choppy animation RAM preview & rendered
                  rahajav2012 Level 1

                  i've attached a number of screen shots, and i hope they help understand my project and problem better. sorry for the insufficient information so far, and thanks for offering to help.


                  here's a more detailed description:


                  the animation is 24 seconds long. starts zoomed in on a part of an image -- and as it pans around it in a circular motion, also zooms out.


                  attached photos called AE project position 1 - 3 show the beginning, middle and end points of the movements. you can see the keyframes for both position and scale. Rick, i took your advice regarding scale and used a file size that at 100% is almost the size i need. rather than zooming in to 150%, now i only have to start at 116%. in the first screenshot, i left the preview size at such a tiny zoom so that you could see the rather large size of the source image i'm using....much larger than the 1440x900 frame.

                  AE project position 1.png

                  AE project position 2.png

                  AE project position 3.png


                  i have tried using keyframe interpolation and the curve on the position parameter to smooth out the speed. screenshot called AE project position curve shows this.

                  AE project position curve.png

                  AE project scale curve.png


                  of course the problem is that if i do 'rove across time' with keyframe interpolation on the position keyframes, then i have to change the placement of the scale keyframes in order for the movement to still work as desired.


                  i have turned on motion blur on the layer.


                  i have then pre-composed the layer and in a new composition, added Timewarp effect (for the motion blur only). as you can (screenshot called AE project composition with effects) i set the shutter angle really high to get lots of blur to try to mask the choppiness.

                  i pre-composed the layer so that i could turn on the little rasterize button. to be honest, i don't know what this does or why it's not available on a layer before it's pre-composed, but it was recommended to me to have it turned on.


                  AE project composition with effects.png


                  when i RAM preview that at about 25% display size, it is ALMOST perfectly smooth -- minus a couple small jitters that are practically negligible.


                  when i RAM preview at 100% it is very choppy.


                  i have tried rendering a few times with different settings. i have tried a few with Photo-JPEG codec at about 75% quality, both at full size as well as half (i'd like to keep it to 1440x900 export if possible)

                  i have also tried rendering to Apple ProRes 422, also 75% quality, tried both full size and half.

                  when i watch any of these rendered results in Quicktime 7, they are jittery. some more than others, but nothing has been satisfactorily smooth...


                  hope this helps understand my issue a bit better. if you have any advice about how i can make this the smoothest possible, i'd appreciate it.



                  • 6. Re: choppy animation RAM preview & rendered
                    Rick Gerard Adobe Community Professional & MVP

                    The kind of movement you describe is much easier to do with 3D layers and a camera. You only have one parameter. You don't have to coordinate scale and position. Movement is more natural than scaling. The project will just be easier in the long run.


                    Also, when you have extremely large images it's usually better to break them up and cut between each as the size matches. It's a fairly easy thing to take the wide shot, duplicate it, scale the copy 50%, then crop the original 50% and line them up in AE using the difference mode. You then just cut from one to the other as you move the camera toward the close up.


                    As far as your ram preview goes it's the incredibly large image you have in the entire composition that is eating up your ram. If you have the info pallet open it is probably showing "not in real time" playback errors.


                    Now let's move to rendering... 1400 X 900 is not a standard size for anything. You should be using standard resolutions for delivery for several reasons. First, highly compressed codecs designed for streaming or delivery on computers have specific frame size requirements. These are based on multiples of 16 pixels. Broadcast (TV) and digital projection is also very picky about the frame size. A few production codecs will render to any frame size you want, and this can be handy in a production workflow, but it's not good at all for delivery. I'd almost be willing to bet that any skipped frames are the result of non standard frame sizes being processed by the CPU for delivery at a standard size.


                    Now let's talk about your choice of frame rate. The lower the frame rate the higher the likelihood that you'll get stroboscopic stuttering or choppy movement. Even filming with a video camera or a film camera at 24 fps can, and often does, create shots that are nearly impossible to look at because of this stuttering action. There's a table of critical pan speeds in the ASC cinematographers handbook I carry with me on a set that shows the number of degrees per second that will result in a smooth pan with a given focal length and frame rate. The problem is caused by the frame rate, the movement of detail, and something we can't change. Human visual retinal retention. Your eye and your brain combined with the movement of details and the frame rate make it impossible to perceive smooth motion at certain critical speeds. If you are not dropping frames and you still see jumpy, hard to look at motion, then you have to change the speed of the motion, change the frame rate, or blur the stuttering frames enough to completely hide the effect.

                    • 7. Re: choppy animation RAM preview & rendered
                      rahajav2012 Level 1

                      Hi Rick

                      thanks a lot for your help.


                      the framerate i've been using is 29.97


                      i guess 1440x864 would be better? for 16:10? i think i was misled there because 1440x900 came up as a display option that i thought was the same as 16:10. thank goodness for math!


                      i will try that first and see if changing that helps. for the next ones, i will definitely look into the 3D layers and camera method.


                      question regarding your suggestion to cut up the image that's so large. does processing it become an issue when rendering as well? or is it just something that eats up CPU during preview?


                      many thanks

                      • 8. Re: choppy animation RAM preview & rendered
                        rahajav2012 Level 1

                        wait a minute....isn't 16:10   1440x900?

                        • 9. Re: choppy animation RAM preview & rendered
                          Rick Gerard Adobe Community Professional & MVP

                          1440 X 900 is not a standard frame size for anything. I'm not sure why you think you need to use it for your frame size.


                          1440 X 1080 is a non square HD format. I wouldn't use that either unless it was specifically requested by a client as a delivery specification. Use the presets. Stick to Square Pixels. You'll be better off. If you need to crop for special picture aspect ratios (Cinemascope, 2:35, others) letterbox the project with a mask. If you are heded for a film printer (not used as much now that Fugi and Kodak are getting out of the film business and only a small precentage of the movie houses in the US and the world still project film) you must use their specifications exactly for delivery. Every film printer has it's own set of specifications. Send them the wrong format, frame size, color depth and you'll just have to re-render the right one.


                          Here are the H.264 (probably the most popular and likely the best streaming format) specs: http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC


                          Choose any other frame size and the codec will not give you what you expect.


                          Here are the specs for ProRez. Although PreRez will render to any frame size, smooth playback is only promised for the sizes listed.


                          You cannot overlook the requirements of the compression scheme and hope for successful playback.

                          • 10. Re: choppy animation RAM preview & rendered
                            rahajav2012 Level 1

                            so i redid the project in as a 3D layer with a camera -- MUCH smoother! and way easier and less time consuming! thanks for that tip.


                            i'm doing 1440x900 because that's what i thought 16:10 aspect ratio translates to. final project is to use a software called Isadora to project these through a HD projector with 16:10 aspect ratio (i actually need smaller than that but i'd like to mask the least amount necessary with video black and have the actual size of the aspect ratio as close to the screen aspect ratio as possible). Isadora suggests importing videos at the same aspect ratio and size as the expected output....


                            however, i changed my composition sizes to 1440x1050 and it's made a huge difference in smoothness as well (i tried this first, before the 3D/camera thing). but that's strange because 1440x1050 is not on the list you sent of sizes supported by ProRez codec. i imagine if i try 1440x1080 that will result in even smoother...


                            since the final project will be blown up over a screen 35' x 21' i know H.264 will not give me the quality/resolution i'm after

                            • 11. Re: choppy animation RAM preview & rendered
                              Rick Gerard Adobe Community Professional & MVP

                              Have you been to a movie lately? Most digital cinema projection is H.264 or h.265. The extreme theaters are JPEG 2000 12 bit. The standard dimensions are 1920x1080 HD, 2K, or 4K.  Make sure you are using the right frame size for your projector. I had never heard of 1440 x 1050.