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Team37427314ez7w
Participant
June 17, 2025
Question

Precomp FPS Mismatches Can Cause Fractional Frames

  • June 17, 2025
  • 1 reply
  • 220 views

These are precomps made from 23.976 fps footage. It looks fine at first, but once I restart After Effects, the timing becomes incorrect as shown below.

This issue has existed since at least 2023, and likely earlier, but I only started using After Effects in 2022, so I can’t say for sure.

 

  1. Version of the app: 2025.3
  2. Platform and OS version: Windows 23H2
  3. Basic steps to reproduce the problem: Precomp a 23.976 fps clip in a 60 fps comp, save the project, then restart After Effects.

1 reply

nishu_kush
nishu_kush
Legend
June 17, 2025

Thanks for reaching out. I created a project according to your steps. However, the position of the layers doesn't change when I save the project and restart After Effects. Also, the layers are not aligned perfectly, which is expected because of the different FPS (Screenshot). Are you moving the layers manually or using Keyframe Assistance > Sequence Layers? If possible, share a project file for testing. 


Thanks,
Nishu

T
Team37427314ez7wAuthor
Participant
June 17, 2025

What I mean by "position" is that the ends of layers will sometimes shift slightly—by a full frame or even fractionally, like 1.2 frames. It’s not a major issue, but it’s frustrating since I like to keep everything neat and properly aligned.

 

As far as I know, the only way to fix this is by time-stretching the layer, or using time remapping, but time stretch alters any animation graphs or keyframes I’ve set, and time remapping messes with Twixtor for some reason, which makes it an impractical solution.

 

I was under the impression that After Effects automatically retimed layers to match the composition frame rate, so for example, 23.976fps footage should be stretched to match 60fps playback, using duplicate frames without interpolation. And that does seem to be the case when layers are added directly.

 

However, once I precompose them, the precomps go from looking correct to appearing slightly extended or retracted at the ends once I restart After Effects as shown in the screenshot. It’s a subtle change, but it’s visually noticeable and quite annoying.

 

Also, yes I'm moving them manually, but it happens even when I don't move them at all.

nishu_kush
nishu_kush
Legend
June 23, 2025

Seems like it is working as expected since the frame rate mismatch. If it helps, try sequencing the layers without choosing to overlap (Keyframe Assistance > Sequence Layers). It arranged layers without any gaps or overlaps for me.

Hope it helps.


Thanks,
Nishu

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