UHD to HD downconvert

[-cicero]

Hi all

Working on a long-form 3840x2160 25p project.  As well as UHD file delivery I'm required to create an HD downconvert delivering on HDCamSR.  Source timeline is 25p but the tape will be 25i.

I want to avoid reformatting the timeline to HD as we've recently had problems doing this - system hangs/crashes, clips with Action slipping media to 0 frame handles at start (probably one for a different thread!), etc.

I've tried using Real-Time Deliverables to render a new clip at 1920x1080 (both 25i and 25p) using Lanczos filtering.  This works and can be output to tape, but on certain clips in areas with very fine detail it is introducing a horrible patterning or flickering, a bit like moiré.

Any thoughts on the quickest, best quality method to achieve this downconvert?

Thanks

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[Anonymous · Accepted solution]

Change Lanczos to something softer like Gaussian.  Lanczos is designed to retain as much sharpness as possible and when downscaling it can introduce buzzy effects like those you're seeing.

[-cicero]

Thanks for your reply Andy.

In the end I used Lanczos but adjusted the crisp/soft setting for an acceptable compromise (the lower quality filters were too harsh).  Thanks for confirming that RTD were the correct workflow as I hadn't needed to use them before.