One of the things we enjoy about running the site is receiving news or tutorials about things in Final Cut Pro X that we would never think about. This is one example, a very clever trick for making progressive footage appear interlaced in an interlaced timeline.

The majority of HD television broadcast in Europe is interlaced. The material might have been shot in progressive, but for the folks watching at home, somewhere in the chain the single frame has been split into fields.

Mixing interlaced and progressive footage on an interlaced timeline isn't really a good idea, it will look odd. So normally to match footage that has been shot on a GoPro or DSLR, you make the interlaced footage drop a field. It's called deinterlacing.

So what if you only had a couple of progressive shots in a timeline and wanted to make them match the interlaced footage?


Hubert Leconte very kindly emailed us his short tutorial on how to convert a progressive shot to interlaced in Final Cut Pro X. Having many broadcast years under our belt, we have to say the scepticism was high.

But do you know, he might have just stumbled on a very clever trick, we tested it out.

Frst we will let Hubert explain:



When you drop progressive stuff on an interlaced project, video viewed on an external monitor will appear jittery. Obviously, one field is missing. Some appreciate this as a "cinema effect" or 'film look' others not.

Here's my solution to make the footage smooth:

Check you project settings are set to interlaced - 1920X1080 -50i. (Or 1440X1080 for HDV) 



Drop the clip on the interlaced timeline

Select the clip, and apply a retiming effect, "Cmd R", at 99% (!).



Afterwards, check "Optical flow" in "Video quality". That's the point.



Final Cut Pro X will start the optical flow analysis. This may take a while depending of the length of the clip.




Once achieved, return to the speed to 100%. 
The clip viewed on your video monitor, through an AJA or BlackMagic device is now played fluidly.

A few notes: 

  • Duration of Optical flow analysis depends of the power of your computer
  • It generates huge files in your library bundle, in the folder "Analysis Files/Optical Flow" Take care of the disk space: The function "delete generated Library files" does not eliminate these ones. If you want to, you have to go manually in the library bundle.
  • We lose a little bit sharpness on the video. Acceptable regarding the quality of the movements.



We tried Hubert's tip out and it definitely makes 2 fields out of a frame, almost 'tweening' between frames.

Take a section of a panning shot that was filmed in progressive on a Canon C300.



After Hubert's trick you can see a second field has been generated with optical flow between frames. You can tell the interlacing from the 'comb' edges.



We don't suggest you use this trick on a whole show and Hubert's warnings need to be taken into account. However it just might help getting that awkward progressive shot you want to use into an interlaced sequence.

Many thanks to Hubert for the tutorial, maybe the process should be called "The Hubert Retiming Trick."



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I am the Editor-in-Chief of FCP.co and have run the website since its inception ten years ago.

I have also worked as a broadcast and corporate editor for over 30 years, starting on one inch tape, working through many formats, right up to today's NLEs.

Under the name Idustrial Revolution, I have written and sold plugins for Final Cut Pro for 13 years.

I was made a Freeman of Lichfield through The Worshipful Company of Smiths (established 1601). Though I haven't yet tried to herd a flock of sheep through the city centre!

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pszilard's Avatar
pszilard replied the topic: #124966 16 Apr 2023 10:31
I realise that I am totally out of my depth here, so forgive me if I am talking rubbish, but what is wrong with just creating an FCP project as 1080i, then dropping your standard progressive clips into it, then exporting as ProRes 422? When I check with MediaInfo, it reports the exported file as Scan Type: Interlaced.

My other approach is to use a 1080p Project, export it then put it through Compressor to convert to 1080i. I might even add that Compressor recipe to FCP outputs.

Are these approaches flawed?
DaveM's Avatar
DaveM replied the topic: #124968 16 Apr 2023 13:53
Your approaches described in your post are valid.

The approach described in the main article a bit of a hack and I wouldn't recommend it.

Any progressive clips you add to an interlaced Project/timeline are interlaced on export (or after rendering). To "force" interlacing on individual clips (e.g. if you wanted to export an individual clip as interlaced) you could select the clip and change the Field Dominance Override setting in the Settings metadata view in the Info Inspector.