Please help - Issue with Camera & possible Cache / previews

[Child Of The Calculator]

Hi please help!

I am animating a sequence (8844x1200, 60fps), on a project i have been completing for a number of weeks.  I have suddenly hit a snag which i cant resolve.  When I have a camera on an object and change a parameter, for example zoom or point of interest, the preview suddenly behaves erratically and shows random variations of the timeline or previous keyframing.  When i clear the cache, it helps for that initial moment, but as soon as i make a change, it happens again.  I've tried turning cache off, that doesnt help.  Obviously its making it impossible to see what movement the camera is actually making.

The issue is not present in the render, it behaves as expected and renders the keyframes on the timeline.

Further info:  8844x 1200, 60fps comp.  One camera with a trapcode TAO layer.  Previewing at Quarter res, 25fps, skipping every 5 frames (tried all variations of preview settings).

Running AE 17.0.0, Catalina 10.15.7 / 384gb RAM / AMD Radeon Pro W5700X 16gb.

[Rick Gerard]

25 fps is not an even multiple of 60 fps. If the comp is 60 fps and you skip 5 frames then the playback is 10 fps. Skipping 2 is 20 fps. Skipping 1 is 30.

I'm not surprised that your memory and disk cache are fouling up. I'd set the disk cache to something smaller. Try cutting it in half. I would also make sure that you have an even multiple of 4 GB of ram set aside for other apps. For some reason, on all of my Macs, any time you can't divide the ram reserved for other apps by 4 and end up with a whole number, things get fouled up.

Are there multiple shots in your comp? I would keep the comp to one shot unless you need to do a transition between that can't be done in an NLE. How long is the comp? I'm assuming you are matching the frame rate and frame size of the image sequence, and I'm also assuming that the frame size and possibly the frame rate does not match the final render because it does not fit any video standard.

[Child Of The Calculator]

I'm aware of frame rate conversions. However, in preview mode, this is the best configuration for me to be able to actually view playback with any motion (that doesn't chug painfully slowly).   All other preview FPS give exactly the same issue.

No, The composition size is not a standard video format, and yes, it matches the final render output, which is fit for purpose.

the composition comprises as described, 1 camera giving a basic zoom, one layer of trapcode TAO. The only other layer is a height map feeding Tao.  1.35min duration.

I'd also be interested to know other opinions on possible causes other than Cache.

[Rick Gerard]

TAO is a serious GPU resource hog. Try turning it off and see how the comp previews. How long a preview are you trying to get?