MAMEWorld Forums - EmuChat - Re: Sony CXA2025AS US

Hi again,

Sorry for the delay. Super busy at work. I'm attaching a zip file with a shader called "yiqcolor" that just encodes an RGB color as YIQ using the standard matrix, applies tint/saturation adjustment, and then takes it back to RGB.

It has presets for the wikipedia YIQ->RGB formula as well as coefficients for the FCC standard, the Sony US matrix you posted, a different Sony YUV matrix, and a custom one that you can define in the shader. Probably most formulas you could find online are just a phase shift away from the standard, but that's fine.

The ZIP file contains a "bgfx" folder that you can merge with the bgfx folder in MAME 0.172. Then you can try out the effect with either the included "hlsl_yiq_tweak" or "yiqcolor" bgfx shader chains.

NOTE: It will stop working with 0173 since MooglyGuy has made a lot of changes to bgfx since 0172.

The shader chain, "hlsl_yiq_tweak", is just the standard hlsl shader chain with the color effect replaced with this and different defaults.

The shader chain, "yiqcolor", is just the color effects and nothing else.

I also included the shader source, as simple as it is.

-greg

> Curious if anyone has insight regarding palette output, as processed through the Sony
> CXA2025AS US decoder matrix, whether it can be implemented as an option with all the
> various shader and video filter possibilities currently available for MAME (?)
>
> Vice...
> https://sourceforge.net/p/vice-emu/code/HEAD/tree/trunk/vice/src/video/render2x2ntsc.c
>
> ...and puNES...
> https://github.com/punesemu/puNES/blob/master/src/video/filters/ntsc.c
>
> ...as well as Nestopia (Undead)...
> https://github.com/rdanbrook/nestopia/blob/master/source/nes_ntsc/demo.c
> ...has an option for it.
>
> It is also applied to (forks of) the Gens/Genesis emulator as well as a part of the
> TwoMBit-Core featuring SMS emulation for OpenEmu.
>
> When selected as a palette option, the color hues are spectacular, nailing the way
> respective console and computer systems appear when displayed on many highly utilized
> and popular computer monitors and televisions.
>
> For those interested, the conversion formula (RGB --> YIQ) for this particular
> decoder matrix is as follows:
> R = Y + 1,630 * I + 0,317 * Q
> G = Y - 0,378 * I - 0,466 * Q
> B = Y - 1,089 * I + 1,677 * Q
> Spec sheet/details are attached.

Edited by SoltanGris42 (04/19/16 09:08 AM)