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Atario
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Reged: 06/15/21
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Fairchild Channel F and HLSL
#391065 - 06/15/21 04:27 PM


Hi, all!

I've just started using HLSL to get that classic scan line look, and it works a treat — most of the time.

However, I'm trying to get my channelf games to quadruple their scan lines (like the original console did). Not having any luck, though. The prescale option seems to do nothing, even though it seems like exactly what I want.

Any clues?



ICEknight
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Re: Fairchild Channel F and HLSL new [Re: Atario]
#391073 - 06/16/21 10:12 PM


Prescale is used for making pixels look less blurry when no shaders are active (making the filtering less obvious when upscaling the emulated output to the full resolution of the used display), I don't think it will have much (any?) effect with HLSL, crt-geom, etc. Scanlines (or rather, the used mask) will always stay in their proper positions unless something goes wrong.

What do you mean that the Channel F "quadruples the scanlines"? Do you have any pictures of this effect on real hardware?



Atario
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Re: Fairchild Channel F and HLSL new [Re: ICEknight]
#391077 - 06/17/21 07:15 AM


You can see it pretty well if you fullscreen this:

https://www.youtube.com/watch?v=wBeokwN_5jg&t=4m13s

Each pixel occupies four visible scan lines on the CRT. (It would kinda have to, at this super low resolution!)

EDIT: You can see it even better a bit later: https://www.youtube.com/watch?v=wBeokwN_5jg&t=5m9s

Also, I probably should have included a screenshot so you can see what I'm getting: https://i.imgur.com/ACQBdb2.jpeg (The snapshot has somehow screwed up the aspect ratio, but you get the idea)

Edited by Atario (06/17/21 05:59 PM)



ICEknight
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Re: Fairchild Channel F and HLSL new [Re: Atario]
#391097 - 06/18/21 09:08 PM


Here's a direct comparison of real hardware versus current emulation:



Haze
Reged: 09/23/03
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Re: Fairchild Channel F and HLSL new [Re: ICEknight]
#391099 - 06/18/21 09:42 PM


> Here's a direct comparison of real hardware versus current emulation:

I guess the issue is that MAME treats the output resolution at 102x58

AFAIK No CRT is going to sync to a display of 58 lines, so the hardware doesn't output 58 lines.

It outputs the same line 4 times before switching to the next to give a much more reasonable 232



Pernod
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Re: Fairchild Channel F and HLSL new [Re: Haze]
#391104 - 06/19/21 03:27 AM


>
> It outputs the same line 4 times before switching to the next to give a much more
> reasonable 232

There's a recent write up of the video hardware over at https://forums.nesdev.com/viewtopic.php?f=23&t=20475 , so it seems PAL machines output the same line 5 times.

Looks like the driver could do with an update based on this new information.



Atario
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Re: Fairchild Channel F and HLSL new [Re: ICEknight]
#391108 - 06/19/21 10:11 AM


ICEknight, can I ask what your HLSL settings are? Those look nicer than mine…

Also, your snapshot came out with the aspect ratio okay, how'd you do that?



ICEknight
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Re: Fairchild Channel F and HLSL new [Re: Atario]
#391136 - 06/22/21 10:09 PM


I'm using crt-geom, instead of HLSL.



Robbbert
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Re: Fairchild Channel F and HLSL new [Re: Atario]
#391152 - 06/26/21 02:21 PM


> You can see it pretty well if you fullscreen this:

This has been fixed:
https://github.com/mamedev/mame/commit/c8192c898ce7f68c0c0b87e44199f0d3e710439b



Atario
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Re: Fairchild Channel F and HLSL new [Re: Robbbert]
#391154 - 06/27/21 01:55 AM


> This has been fixed:
> https://github.com/mamedev/mame/commit/c8192c898ce7f68c0c0b87e44199f0d3e710439b

Nice! Thanks, you guys are the best


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