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 Post subject: best upscaling algorithm in VirtualDub for retro games
PostPosted: Sun Mar 19, 2017 11:05 pm 


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Joined: 08 Mar 2015
Posts: 1379
Here is the list I got in VirtualDub 1.10.4, which one is the best for upscaling 240p graphics?

Nearest neighbor
Bilinear (interpolation only)
Bicubic (interpolation only)
Precise bilinear
Precise bicubic (A=0.75)
Precise bicubic (A=0.60)
Precise bicubic (A=1.00)
Lanczos3

I know I could render 1 of each and take snapshots and compare, but that would take a good while and if somebody already has the answer to this and don't mind sharing, it would save me a lot of time and efforts.

Thanks!


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 Post subject: Re: best upscaling algorithm in VirtualDub for retro games
PostPosted: Sun Mar 19, 2017 11:31 pm 


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Joined: 06 Mar 2006
Posts: 10270
Location: Germany
You do a next neighbour upscale to about 2x your target size (and keep it integer) and then a precise bilinear downscale to your target resolution.


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 Post subject: Re: best upscaling algorithm in VirtualDub for retro games
PostPosted: Sun Mar 19, 2017 11:51 pm 


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Joined: 08 Mar 2015
Posts: 1379
Thanks! Woah I've got a ton of questions now.
Wait : so I need to upscale and then downscale? are you messing with me lol

What is target resolution exactly? the final size I'll be uploading to Youtube? For me that would be 720p (1280x720)
Also, I capture at 720x240p, but linedouble in Amarec. So the file I import in VirtualDub is 720x480

So I should next neighbor upscale 3X integer (2160x1440) and then precise bilinear downscale to 1280x720?
Can I put both these filter in the same rendering process? or should I do them separately


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 Post subject: Re: best upscaling algorithm in VirtualDub for retro games
PostPosted: Mon Mar 20, 2017 8:12 am 


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Joined: 06 Mar 2006
Posts: 10270
Location: Germany
When you're capturing at 720x240 your horizontal sampling isn't perfect anyway, so the result won't be perfect, unless you downscale to the physical resolution first. To do so you're cropping away the overscan first and then do a NN downscale to the physical resolution of your source (e.g. 256 pixels for SNES). Then you upscale using NN and downscale using Prec.BL.

If you're using a codec with reduced color sampling (e.g. 4:2:2) I would do the same for the vertical scaling. If done right you can usually achieve "emu-like" results. The point of using the BL downscale is to give you the best possible result without shimmering that would otherwise occur due to the NN scaling.

You can create the whole processing chain at once. Cropping -> horizontal NN downscale to the exact sample rate -> integer upscale -> Prec.BL downscale.

If you don't mind the vertical underscan and whish to leave it, you can keep the vertical scaling integer all the way.


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 Post subject: Re: best upscaling algorithm in VirtualDub for retro games
PostPosted: Mon Mar 20, 2017 6:31 pm 


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Joined: 08 Mar 2015
Posts: 1379
ok thanks


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