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jerky playback in RAM preview and QT, but not errors in animation
We are experiencing heavy stuttering or jerking attempting to view certain types of animations. The problem persists with several codecs, regardless of pixel size or compression, both in the Quicktime player and within Adobe After Effects 7. We have tested rendering out directly into quicktime format with different compressions (including sorenson, animation, motionjpg, h264, etc), and rendering out many types of image sequences (including jpg, tiff and psd) and loading them up in quicktime player. We’ve rendered out both 480×270 and 960×540. The problem has occurred on both a G5 Dual 2 gig with 3.5 gb of ram (running quicktime 7.1.6), and an octocore with 4 gb of ram (running quicktime 7.1.3). Both machines are running OSX 10.4.9 system software. Another employee here made a DVD of this animation, compressing using apple products and using DVD Studio pro, and the jerkiness translated onto the DVD when viewed on a G5 (don’t have access to a set top box). This DVD was cropped to 4×3 (720×480).
The jerkiness is completely random, always occurring in a different place, and not tied in any specific way to the motion. When viewed frame by frame the animation is completely smooth. The animation involves panning across a flat, large bitmapped image over 30 seconds, so no frame rate or interlacing issues are involved. The problem occurs both when using a 3D camera, and when animating in 2D using position keyframes. Motion blur at 180 shutter speed is turned on. There is a lot of contrasting detail in the image, so a lot of information is being conveyed pixel to pixel. I am able to recreate the effect panning across various other test images as well (for example, I tested a world map).
The stuttering has that look as if the hard drive is too slow, but as the problem persists even with 480×270 highly compressed quicktimes (i.e. sorenson) under 5 mb in size, so hard drive speed should not be an issue.
Other quicktimes, such as stock standard def footage that doesn’t involve panning, seem to play fine.
The problem seemed to start when we upgraded to AE 7, but that might be a misnomer since maybe it’s the nature of these designs.
There is no audio tied to these files.
It seems the problem might be quicktime, but with two different versions of quicktime showing the same problem, and the fact that the problem also persisted in Maya’s FCheck application, makes me unsure (but for all I know FCheck also utilizes quicktime resources to work as well.)
The video cards involved are the GE Force FX 5200 (G5) and the Quadro Effects 4500 (Octocore).
This problem is severe for us as we are unable to see what our designs actually look like, and we are at wits end trying to solve it. Not to mention how clients feel looking at jerky previews and their comfort level with that. Delivery is approaching an no solution is in site. Any help would be appreciated.
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6 Replies
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Out of curiosity, when you RAM preview what does it say the frame rate is in the Info palette?
Darby Edelen
DVD Menu Artist
Left Coast Digital
Aptos, CA -
It says it is playing in realtime — in comps at both 24fps and 30fps, at both half and full size.
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Thanks for your exhaustive testing. Most people don’t give us enough info. 🙂
Hmm … if you have the time, try:
– panning vertically
– panning more quickly
– panning quickly, then slowly, then quickly … not letting the eye get used to it.
– panning horizontally, but with a vertical component so you get a sine-like motion.I know it’s a lot, but if you could let us know if the stutter looks any different, that might help.
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haha! Well, just so happens I have tried all of these things… we are currently at a version that has horizontal, vertical, sine-like/combination moves, etc. at a much much slower pace than originally (the entire piece is about 40 sec long). Unfortunately the problem still exists.
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Hm. Are you aware of the optical phenomenon where a pan can look jerky because the frame rate is too low to create persistence of vision?
… even when we have no choice over the frame rate?
I’ve seen it on films such as Spike Lee’s Inside Man, during a nasty pan over some pictures in the Security Guards’ office.
Do you know whereof I speak?
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Yes, I am familiar with that problem, and have had it on other projects, but this is definitely something different. Thanks, though!
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