VOGONS


First post, by NightShadowPT

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Hi,

I've been looking (and failing miserably) for an upscaler to use with my 486DX2 that would get the VGA output into an HDMI connection to my 4:3 LCD.

I am specifically looking for an upscaler that can deal with CRT emulation features like Aperture grill emulation, pixel bloom, scanlines, etc.

The only thing I can find at the moment is the Retrotink 4K, but that thing is massively overkill for this use case (not to mention expensive).

Any ideas?

Thanks

[Edited] corrected "scanlines"

Last edited by NightShadowPT on 2024-12-09, 16:29. Edited 1 time in total.

NightShadowPT
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Reply 1 of 4, by Tiido

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That only thing you found is the only thing there is that can do such stuff. The features you mention are far from being trivial to implement (apart from scanlines, those are easy) and require significant processing power to do, especially in realtime situations.

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Reply 2 of 4, by clb

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NightShadowPT wrote on 2024-12-08, 19:29:

I am specifically looking for an upscaler that can deal with CRT emulation features like Aperture grill emulation, pixel bloom, scantiness, etc.

These are sophisticated features that require understanding from multiple domains, e.g. electrical engineering manufacturing and design, signal processing, vintage hardware behavior and human visual perception. (scantiness = scanlines?)

NightShadowPT wrote on 2024-12-08, 19:29:

The only thing I can find at the moment is the Retrotink 4K, but that thing is massively overkill for this use case (not to mention expensive).

Retrotink 4K ($750) has a powerful Intel Cyclone V FPGA (around $300 per FPGA), and is a result of several years of dedicated R&D to deliver the abovementioned CRT emulation profiles in a real time video processing environment.

It is hard to think of competition in this area that could implement the same at lower price point with cheaper hardware. They are the only game in town with that feature set, and are on their fourth hardware iteration, since 2018 or so.

To compare against CRT Terminator Digital VGA Feature Card ISA DV1000 (220€ VAT0%): The project took more than four man-years to develop and unfortunately the FPGA is not nearly as powerful as the Cyclone in Retrotink.

I spent two months prototyping a CRT scanlines implementation for CRT Terminator, and with the limited processing power that it has, here are rough sketches of what it could have been at the limits of the computing power it provides:

720x400 without and with scanlines:

The attachment 720x400.png is no longer available
The attachment crt_scanlines_720x400.png is no longer available

320x200 without and with scanlines:

The attachment 320x200.png is no longer available
The attachment 320x200_crt_scanlines.png is no longer available

But turns out the feature took up way too large portion of the FPGA floorplan, and was not possible to fit. As for the visual quality, well, given you are aware of terms like aperture grill and pixel bloom, let's just leave it there.

However maybe that data point can give a ballpark of the multiple dimensions that these types of development move like. I would be highly surprised if some group managed to beat Retrotink 4K hardware with such "shader quality" CRT scanlines requirement at a more competitive price point than them. OSSC would be the only possible competition here, though given that OSSC Pro was released just last year, I doubt they'll be one-upping Retrotink 4K in a few years at least.

Reply 3 of 4, by elszgensa

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Here's an idea if the RT4K is too pricey for you: Head on over to the VGA capture thread, get a clean capture on your PC at, or close to the original resolution (this alone is more of a problem than you may think); upscale and add whatever filters you want and output through HDMI. Won't technically be cheaper than the RT (PCs do be expensive...) but you probably already own most of it so it won't seem like that to your wallet, at least.

I gotta ask - where did you manage to find a high res (I'm assuming 4- or at the very least 2K) 4:3 LCD? Because, as you - but maybe not everybody else stumbling into this thread - already know, most filters of the sort you're thinking of will not look good on a lower res one. e.g. if you try pixel bloom but don't have multiple physical pixels for each virtual one (so you have an "edge" to apply the effect to), all you end up doing is blur the entire image. Simulate grid lines onto too few pixels, now you're just slightly darkening some of them. etc

Reply 4 of 4, by rmay635703

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Or just do what everyone else does and just use a cheap Temu or Aliexpress box that gets vga to display on HDMI and don’t worry about that other stuff

Some of the devices will allow you to adapt any video signal to any other video signal type (svideo, composite, component, 15khz RGBS/SCART, vga, HDMI

elszgensa wrote on 2024-12-09, 09:15:

I gotta ask - where did you manage to find a high res (I'm assuming 4- or at the very least 2K) 4:3 LCD? Because, as you - but maybe not everybody else stumbling into this thread - already know, most filters of the sort you're thinking of will not look good on a lower res one. e.g. if you try pixel bloom but don't have multiple physical pixels for each virtual one (so you have an "edge" to apply the effect to), all you end up doing is blur the entire image. Simulate grid lines onto too few pixels, now you're just slightly darkening some of them. etc

Yeah I was wondering that as well there is only one model of 24&25” 4:3LCD and they look abysmal at any modern resolution.

There are high resolution (2048x1536) 4:3 screens but they are all 8” or smaller or 21” Medical scanning screens.

http://www.widecorp.com/?act=shop.goods_view&GS=77&GC=GD0800

The 20” & 21” 4:3 LCDs all max out at 1600x1200 and the pillar boxed 19:10 that scale 4:3 are also 1600x1200 in 4:3 mode.

https://www.amazon.com/Unico-inch-Arcade-Moni … s/dp/B0C4NXDRNM

There is a single 23” 4:3 Samsung lcd panel but I don’t know of anyone with it.