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Old 1st February 2022, 14:23   #1  |  Link
JClement
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Join Date: Oct 2010
Posts: 27
undoing improper resizing of interlaced video

I have a video of a movie that was resized from 720x480 to720x536. The original, which I never had, was obviously properly telecined 3:2. So I want to restore the original frames, then detelecine to then do a proper restoration.

So, my question is whether there are deconvolution algorithms for undoing an improper vertical resize. I would need the deconvolutions for the common resizing algorithms as I do not know which one was used.

The undo would involve a variety of trials as there may have been some cropping. One would think the resize would have been to 540 as the person who did this apparently wanted to produce a proper 4:3 aspect ratio and didn't understand that there is embedded metadata to do that by the player.
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Old 1st February 2022, 16:33   #2  |  Link
poisondeathray
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Debicubic and debilinear would be the most common, but the situation is often complicated by lossy compression and getting clean results is difficult

Another approach is to interpolate over the combed frames . A recent example was posted in this thread
https://forum.doom9.org/showthread.php?t=183705

Rife tends to do a better job overall than mvtools2 in many situations , but it's not available for avisynth (only vapoursynth) , but any type of intermediate interpolation can often have various issues with edge artifacts, blending, errors
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Old 1st February 2022, 17:26   #3  |  Link
johnmeyer
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Location: California
Posts: 2,691
I came up with a method that made substantial improvements. Here is a link to the thread where I developed the technique:

repair bad deinterlacing

Post #15 is where I came up with my first, crude script.

Here is the post that contains the "final" code I created:

https://forum.doom9.org/showthread.p...09#post1686309

This shows some "before/after" shots:

https://forum.doom9.org/showthread.p...43#post1686243

The code was "hard-wired" for the particular video and would have to be modified for the height of the combing artifacts in your video. I never spent the extra time to generalize the function.

As always, many thanks to StainlessS for his help.

Last edited by johnmeyer; 1st February 2022 at 17:28.
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