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Animation is "Chugging/Skipping" - WHY?

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Lillian YoungAnimation is "Chugging/Skipping" - WHY?
by on Sep 30, 2009 at 6:41:35 pm

I have a simple animation. It's a long (flat) image (attached to an animated null) moving from one side of the screen to the other. There are two keyframes, 30fps. That's all.

Visually, the image starts at the beginning of the image, runs along the screen and stops at the end of the image.

When I export it however, it "chugs," meaning that it seems to have a non-smooth 'skipping' motion.

My initial thought was to change the keyframes. I tried rotoscope, easing and regular keyframes, all to no avail. I cannot change the timing of the image because it's tied to another video, so the timing HAS to remain the same.

I even tried to apply a smoother, but it wouldn't allow any change of values. Hmm.

Any ideas? My colleagues and I are super stumped.

Thanks in advance!


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Steve RobertsRe: Animation is "Chugging/Skipping" - WHY?
by on Sep 30, 2009 at 6:46:47 pm

Try searching the COW for "judder".



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Dave LaRondeRe: Animation is "Chugging/Skipping" - WHY?
by on Sep 30, 2009 at 6:59:04 pm

[Lillian Young] "When I export it however, it "chugs," meaning that it seems to have a non-smooth 'skipping' motion. "

You DID Render using AE's Render Queue, right? If not, you should: it's lots better.

And unless you're working under extraordinary circumstances which you already know about, you DO mean 29.97 fps when you write 30 fps, right?

I bet you made a high-quality file, which is the way to do it. But when you play it back through your media player, your poor little hard drive can't keep up with the high bitrate of the file, and it plays in fits and starts.

It happens all the time to the uninitiated.

To reassure yourself that everything's fine, you should render TWO files: one high-quality, and one compressed in something like mp4 or h.264. It won't look great, but it ought to play back smoothly and that's its sole purpose in life.... and you can make 'em both at once.

How do you render two files at once? Add your comp to the Render Queue, And set the Output module for a high-quality file like you're used to making. Then use the Add Output Module command. Another Output Module shows up in the Render Queue, and you set THAT one to make a compressed file.

See how handy that Render Queue is?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Lillian YoungRe: Animation is "Chugging/Skipping" - WHY?
by on Sep 30, 2009 at 8:40:54 pm

Hi Dave - I rendered at 30fps, not 29.97, and yes from the AE render queue.

Our Mac Pros have the torque, although we all questioned the processor of each machine, which would yield varying results. And we tried varied quality renders, but they all yielded the same result.

I passed it to a colleague to help, but thanks.


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Dave LaRondeRe: Animation is "Chugging/Skipping" - WHY?
by on Sep 30, 2009 at 9:44:44 pm

[Lillian Young] "Our Mac Pros have the torque, although we all questioned the processor of each machine..."

The processor speed and number of cores on your machines is irrelevant if the hard drive can't keep up with the bitrate of the file.

Unless you happen to have your machines hooked up to RAIDs, I suspect that's the problem: I don't think your drives can keep up.

Here's a test: if your RAM Previews play in real time and the previews look smooth, but the rendered file's motion isn't right, it's probably the speed of the hard drives.

If you're reluctant to re-render in AE to teest for smooth playback as I mentioned earlier, compress the file you have using another application like Apple Compressor, Adobe Media Encoder, etc. Compressing to something like mp4 or h.264 should do the trick.

And unless you're CERTAIN you should be rendering at 30, you probably ought to be rendering at 29.97, because that's the frame rate of NTSC video. Are you CERTAIN you should be working at 30?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Steve RobertsRe: Animation is "Chugging/Skipping" - WHY?
by on Oct 1, 2009 at 1:11:00 pm

Dave's solutions are all valid, but the reason I so glibly suggested searching for "judder", is that your post described your animation as a steady horizontal motion. Like it or not (sorry!), the experience of many suggests that regular, simple horizontal motion appears to skip, jerk or judder, and there's nothing that can be done at normal frame rates.

It has been suggested in the COW that this is an optical phenomenon, where the motion is smooth enough and regular enough to interfere with the usual short-range apparent motion, often called "persistence of vision". It has also been suggested (though not in the cited paper) that the regular horizontal motion is slow enough and regular enough for our eyes and mind to actually discern the individual images in the clip, which is, after all, what we are looking at.

If you concur, then you might want to a) distract the viewer with changes in speed, motion path or additional animated objects so they don't get too used to the motion, b) speed it up a little or c) ask the client what he/she thinks before going to all that trouble. They may think it's fine.

Hey, it shows up in panning & tracking shots in movies all the time, such as Inside Man (pan across a wall in a security office?) and The Bourne Supremacy (the bridge shot right after "Gilberto de Piento).



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Lillian YoungRe: Animation is "Chugging/Skipping" - WHY?
by on Oct 4, 2009 at 9:13:40 pm

Dave and Steve - Thank you both for your responses. You've offered a lot for me to think about scientifically as well as share because this truly has me shrugging my shoulders.

Here's a sample of the motion using basic solids and text. The exact staggering is happening with these basic images:

http://img21.imageshack.us/i/staggeredvideo.mp4/

@ Dave - I have to export at 30fps per the Flash developer's request.

@ Steve - Funny you mention it because before returning here to read responses, I did offer alternative animations which included varied speeds. I find that often showing alternatives yields better results than verbal explanations about why things won't work.

I wanted to come here to make sure that it's not poor animation on my part, and based on what's been stated re the horizontal motion and the eye, plus my very simple example above, I a better informed.

If asked to create an animation of this sort moving forward, I will be better prepared for what to expect. This took me totally off guard because of its simplicity.



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