Best Practices for Sharpening UHD 50p Footage in Progressive Timeline Before 50i (25i) Export

[Peter Reef]

I'm editing UHD 50p footage for broadcast delivery (1080i 50i XDCAM format). Based on performance issues and recommendations from the community, I'm working in either a UHD 50p timeline or HD 50p timeline rather than directly in a 50i timeline, then exporting to 50i (or call it 25i if you like) at the end.

The Challenge:
I need to apply sharpening to my footage (particularly flattened LOG material and drone footage), but I'm concerned about introducing interline twitter, moire, and aliasing artifacts that only become visible in the final interlaced output. Since I'm working in a progressive timeline, I can't see these potential issues during the editing process.

Specific Questions:

1. Sharpening Technique: When working in a (UHD) 50p timeline but exporting to 50i, should I use different Unsharp Mask settings (Amount/Radius/Threshold) compared to progressive-only workflows to account for the interlacing conversion? Will sharpening UHD footage before downsampling to 50i cause even more interline twitter?

2. Timeline Choice: Is there a quality difference between:

   • UHD 50p timeline → export to HD 50i

   • HD 50p timeline with UHD footage → export to HD 50i

   • Will effects like Warp stabilizer work differently?

3. Preview Strategy: What's the best way to preview potential interlacing artifacts during editing? Should I create test exports periodically, or are there other methods to catch moire/aliasing issues early? Should I get a converter box like Decimator MD-HX just to preview in 25i?

4. Equipment: MacBook Pro with Blackmagic UltraStudio 3G for monitoring.

Current Observation: I've noticed that moire artifacts from drone footage are only visible when viewing true 50i output, not in the progressive timeline preview.

[Averdahl]

Do you need to sharpen it or do you think you will need to sharpen the footage? My experience is that UHD footage downscaled to HD 50i looks very sharp without doing nothing at all, hence the question. Sharpening are known for introducing interlace artifacts.

As for question 2: I would work in a UHD timeline and export as 1080i50. I have done many tests and the differences are, IMHO, so very, very minor. Do some tests since you are the one that must decide what looks best for you. It also depends on your source footage, iow if you will use any 1080 or SD material in your edit. If anyone in the future want a UHD version it is very handy to have it ready rather than redo/fix/upscale much of the work.

As for question 3 i do recommend to do all cuts on even frames in a 50p timeline if you intend to export to 50i. If you do the cuts on even frames it will look good at 50i while you will see artifacts if you cut on uneven frames. Example of even frames is 00:00:15:14 while uneven is 00:00:15:13 or 00:00:15:15. Since 50 whole frames will be baked down to 25 interlaced frames this will make a difference. I could see the difference when i watched the material on a television set and i could definitely see it when i watched the material frame by frame on the computer. 

If you dont do that you will have interlaced frames that have one field from clip A and one field from clip B at that cut point and they will be shown at the same time. Thats a bigger issue for me than sharpening...

I'm editing UHD 50p footage for broadcast delivery (1080i 50i XDCAM format). Based on performance issues and recommendations from the community, I'm working in either a UHD 50p timeline or HD 50p timeline rather than directly in a 50i timeline, then exporting to 50i (or call it 25i if you like) at the end.

By @Peter Reef

[Peter Reef]

Hi @Averdahl thats a great answer! Glad, that you performed tests on exactly this issue.

On my last documentary (30 min) I worked in an interlaced timeline directly with my UHD footage and had so many issues (performance, effects like warp stabilizer not working). So I will definitely work in a P timeline this time. 

So far I didnt find anyone that is working with only p footage in an i timeline. So i am sure p timeline and export in i is the way to go..

I am shooting in Slog3 on the Sony FX3, which has no sharpening applied at all, so usually its intended to sharpen in post. 

When I worked in my 50i timeline they were complaining that it didnt look as sharp as they liked, although the UHD footage was perfectly in focus. So I applied some post sharpening and everything was fine. 

Maybe its different when I export a p-timeline instead of working in i? 

I didnt know that cutting on uneven frames will be an issue. How do you manage that, do you check on every single edit if its located on which frame?

Does this issue make the film to be rejected by the station?

Some are even using interlacing hardware like the decimator hd-mx to live preview the p timeline as interlaced, is it worth it?-

How do you preview your footage?

I am using a BM ultrastudio mini monitor 3g to downscale to HD. It is not able to interlace. 

I guess you will review the final output in an interlaced timeline.

Does it make a difference if i connect the breakout box to my monitor or to a television?

Some people recommend to always use a television for monitoring interlacing.

[Peter Reef]

So all in all I tested some options and just edited a short piece in UHD.

I definitely need to apply some sharpening to the FX3 to get the right "broadcast look" - I think I can get away with about 20 percent lumetri sharpening of the UHD picture before export. This way theSony footage matches the oversharpened look of the drones a littel.

Therefore I add an adjustment layer to the Sony parts in the picture. 

Still there may be issues with aliasing, but then I need to deal with it when reviewing the final export. Coult take a while going back and forth when scenes have lots of detail.

As the even/uneven frame issue: I never heard of this being an issue. I can see these uneven-frame-cuts when watching still frames but not on playback. Did you have some productions rejected because of of this issue? 

Would you recommmend sharpening the UHD footage before downscaling or sharpening HD 50p before insterlacing recarding interline twitter and artifacts? Did you test it as well?