4K export not possible without ruining video?

Pictures, or rather video are worth a thousand words.
Due to the nature of the video I am creating, exporting in 4K provides a very noticeable increase in quality, and so would like the image to be corrected while I export in 4K.

If you change the resolution of your project, you need to adjust all filters related to size and position because it is not automatic. You should choose the best resolution to use at the beginning and then use proxy and preview scaling features to make it perform better while editing.

That is unfortunate… never had this issue with Windows Movie Maker, and that is considered the “worst” video editing software out there, but evidentially had it’s advantages.

Even if you just select 4K at the export stage, if the videos are high quality enough the resulting video will still be better than just 1080p. Especially for youtube as they will convert your resulting video to a lower quality one anyway.

But yes, starting from begining in 4K video mode is better but you need a much better computer to edit that way.

Exporting FHD (1080p) footage as QHD (2160p) will give a worse result than exporting a 1080P video, replacing 1 pixel with 4 calculated ones don’t improve anything besides the need for extra CPU and storage IMHO

I strongly disagree with this, if this pixel area is in an uncompressed or some native format (and it is before the frame is sent to the (let’s say) x264 encoder) then scaling it (using any interpolation except nearest neighbour of course) to 4x pixels will yield better details in the final output.

Edit: I did a quick png test and at 100% I can’t actually see any difference, I had to go 2x zoom to see more sharpness in high details area on the 4k export, altough maybe they were added by the scaling? Exporting .png might affect the point as it’s basically lossless but jpg or mp4 add way too many variables to have a valid comparison. I still think theoretically it should be a better quality, but not really by that much to be worth the extra encode time.

You kind of hinted at the solution which I just found out - shotcut needs to be set at 4K at the outset for the images not to be distorted - but of course some of my videos are up to 2 hours long, and it will be hell on my computer… but at least instead of being at the default of 720p, I can at least upgrade it to 1080p HD 60fps, whilst stopping my computer from crapping the bed.
This thread is resolved.

Scaling from FHD to QHD is 4x Digital Zoom, every body knows that digital zoom loose quality.
But your eyes can cheat you, a 1080p movie, can look better on a 4K screen than on a 1080p screen, because the PPI count is higher on the 4K Screen.

That is not generally true. Most 4K film and TV 4K is still upscaled content and not just for marketing purposes. It is because something downstream will do scaling for fullscreen playback on a 4K screen; so, do you leave it to your playback device or TV, or try to do it better than those? Also, there is machine learning based super scaling such as NVIDIA DLSS that is usually better than the algorithmic approach.

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Yes, not all scaling algorithm are created equal, so if you can do better than your screens upscaling, it will be better. but when you upload you better encoding to youtube, you will properly loose the improvement

Except that there is some tribal knowledge that if you upload >1080 to YouTube it goes through an enhanced processing pipeline that uses the vp9 or av1 codecs. However, I am not confident that is true any longer as I have a 720x720 uploaded July 2022 that shows vp9 in stats for nerds.

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