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Old 15th July 2020, 23:27   #1  |  Link
orion44
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Why should deinterlacing be done after cropping?

http://www.mplayerhq.hu/DOCS/HTML/en...-telecine.html

The above article states:

Quote:
Also, deinterlacing should be done after cropping and before scaling.
Why should deinterlacing be done after cropping?

I always deinterlace first, and then crop and resize.

Will I mess up my encodes if I deinterlace before cropping?
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Old 16th July 2020, 06:51   #2  |  Link
manono
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The guy says, "For interlaced (not telecined) video, you must always crop vertically by multiples of four...". If you don't, you'll royally screw up the video. Me, I'd rather deinterlace first. If deinterlacing is even called for.

He also claims, "Telecined video was originally filmed at 24000/1001, but was telecined before it was written to the DVD." so I'm not sure I'd believe all that he says.
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Old 24th July 2020, 23:30   #3  |  Link
orion44
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Quote:
Originally Posted by manono View Post
The guy says, "For interlaced (not telecined) video, you must always crop vertically by multiples of four...". If you don't, you'll royally screw up the video. Me, I'd rather deinterlace first. If deinterlacing is even called for.
Why does interlaced video need to be cropped vertically by multiples of four?

After the video is deinterlaced, is it ok to crop vertically by multiples of two?
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Old 25th July 2020, 06:44   #4  |  Link
manono
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Quote:
Originally Posted by orion44 View Post
Why does interlaced video need to be cropped vertically by multiples of four?
You can figure out the answer yourself by just reading on AviSynth's Crop page.
Quote:
After the video is deinterlaced, is it ok to crop vertically by multiples of two?
Same answer as before.
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Old 1st August 2020, 11:24   #5  |  Link
foxyshadis
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Quote:
Originally Posted by orion44 View Post
http://www.mplayerhq.hu/DOCS/HTML/en...-telecine.html

The above article states:

Also, deinterlacing should be done after cropping and before scaling.

Why should deinterlacing be done after cropping?

I always deinterlace first, and then crop and resize.

Will I mess up my encodes if I deinterlace before cropping?
Honestly, that line was written 20 years ago, when CPU power limits meant that deinterlacing unneeded pixels might mean the difference between 2 fps and 4 fps. (And if you go all-in on QTGMC, it can STILL be that way.) Documentation is the last thing to get worked over, so a lot of advice from the 90's and 00's is still floating around.
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Last edited by foxyshadis; 1st August 2020 at 11:27.
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