Jump frames using Vuo FxPlugs and Final Cut Pro

I created a Vuo composition from the FxPlug Transition template and exported it as an FxPlug to use with FCPX. The transition works, but it skips some frames when rendering. This results in a jerky render.

The animation itself is smooth, but the video playback isn’t. For example, if I animate the size of a clip, the size animation will work as expected, but it will skip video frames and duplicate others.

Below is an example using a transition made with Vuo. I used clips with timestamps so it is easier to see what I’m talking about. If you play it frame by frame, you can notice frame 3:25 has been skipped, as well as 4:00, 4:02, etc…

Here is a 10x slow down version:

I haven’t found a workaround, and this issue is really inconvenient for me since I’m trying to develop and distribute plugins for Final Cut Pro.

Any help or hints on how to fix or get around this problem is welcome.


My setup:

  • MacBook Pro 2021 M1 Max
  • macOS Ventura 13.6
  • Vuo 2.4.3
  • Final Cut Pro 10.6.10
  • Motion 5.6.7
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This is probably redundant, but have you checked that all the source clips are the same frame rate as the timeline?

I don’t know if the clips frame rate really matters since FCPX seems to do the job of converting the frames to match the timeline frame rate. I checked and it happens also when using 24fps clips on a 24fps timeline.

Understood — I thought it might explain the missed frames, as that’s what would happen with 30fps clips in a 25fps timeline. If you’ve seen it when frame rates match, that’s a problem.

If you step through the effect frame-by-frame in FCP, does it work correctly?

I get the same result when going frame by frame in FCPX. I think the error occurs when the effect is being rendered on the timeline.

@marinoo1, thanks for reporting this, and @funwithstuff, thanks for your help in troubleshooting.

Using transition-show-both.vuo, I was able to reproduce an issue where occasionally the composition’s input images aren’t updated when exporting a movie from FCP. We have a fix planned for the next Vuo release (tentatively in a week or two).


Perfect, your example shows well the timing problem. Thank you Vuo team for the quick response!

Fixed in Vuo 2.4.4.