Jerky Stills after Transform

I have a 4K, 25p, prores 422 timeline with GoPro 25p footage and a number of jpegs.
I transformed the jpegs. I keyframed them to change position, scale and rotation.
After rendering and even after sharing the video, the movement of the stills appears jerky!

I turned them into Compound Clips without transform and then transformed the Compound to see if that would help. Unfortunately it did not help.

Using the RAW version of the picture seemed to help a little, but still not really smooth.

Does anyone know what is going on?

Thanks, Edwin

What is the format you are exporting (codec, frame size) and what are your Mac specs?

Hi Ben,

I think I did a "Apple Devices HEVC 4K 8bit" via Compressor. I had a 2015 iMac, with and i7, 32GB RAM, 3,13TB Fusion Drive and the biggest GPU they had back then. I forgot which one, because I recently sold the machine and bought a Mac mini M1, 16GB RAM.

I noticed something strange though, the info of the jpeg's in FCP X shows that they are "60p" !?!
The Compound Clips to which I have converted some of the jpeg's (as a test) have of course conformed to the project which is 25p. However, strangely enough, the jpeg's inside the compound clips now also show 25p.

That's normal. Stills always show as 60fps in the browser. They of course have no actual frame rate. 

Did you create fairly fast movements for your Jpegs? I wonder if you see normal motion 'stutter' because your movement on your stills don't have any motion blur applied? Same effect as you see with fast pans on progressive video footage. FCP doesn’t apply motion blur nor does it have a filter to do so. The only way I know of is to create an empty title template in Motion (doesn't contain a title, just the title background) which has the motion blur settings applied in the project inspector. Connecting this template above your stills will render the motion blur for your stills movements.

Yes indeed. I found out.
Weird nevertheless!
Thank you

That is very perceptive and true Carsten. The movements are fairly fast indeed.
I'll see if I can arrange that Motion Template or maybe buy a plugin that does that for me.

Thank you .. very good idea!

Well waddayaknow!

I am probably not allowed to mention a webshop / commercial plugin seller, but I just found "FCPX Motion Blur"  which is actually FREE! ... but not yet available for M1 and as it is free, will probably be the last to be adapted.

..... aaand as a final note :

Of course Steve and Mark have a MacBreak Studio Episode 342 : Adding Motion Blur in Final Cut Pro X ! )

Mark explains the ins and outs of doing what Carsten suggested ... creating a blank title for motion blur.