MAMEWorld Forums - EmuChat - Re: Sony CXA2025AS US

I'm out of town until tomorrow evening and I don't know if I'll have time then.

But it's easy-peasey to write a shader that can (gamma correctly) encode/decode YIQ with whatever matrix you want and provides tint/color controls as well. I could have it let you chose between pre-defined decode matrices and/or let you provide your own.

I can post a modified version of the hlsl.json along with the the new bgfx shaders/effect json files/source here if you want. I can also provide a simpler shader chain that applies only the color corrections without all the other stuff from the hlsl chain.

Are there other matrices besides the standard matrix and the Sony IC that are worth pre-defining? I'll take a look around the interwebs and see.

Of course, I'm not a MAMEDEV (or any dev) so don't expect MAME to adopt it.

> > What are these highly popular TV models with these blue skys? When was the
> CXA2025AS
> > first integrated into TVs? Why is this decoder so special, as opposed to other ICs?
> > Is it because the matrix is different? Every decoder will have a different matrix.
> > It's why NTSC stands for 'Never the Same Color' but you are supposed to use the
> tint
> > and phase control to get the correct colors (that's why they are there), and I've
> > never seen a TV that couldn't be corrected. The only objective criterion I have
> seen
> > for how an NTSC television is supposed to look is the NTSC standard itself. To
> > support this standard I can name dozens of consumer-grade television sets that can
> be
> > tuned (by the consumer) to look pretty damn close to the standard.
> >
> > MAME already let's you adjust the colors, so if you want shitty colors you can do
> > that now, and keep the save file for personal use, or put it up on your GitHub if
> you
> > want to help others achieve shitty colors, too, but I don't think it should be an
> > official option since it doesn't seem to be founded on any reality, but is rather a
> > 'this looks kind of like how I remember it so it must be correct' conjecture.
> >
> > The alternative is to emulate every NTSC IC in MAME, along with the options to
> > control the service parameters like a real TV. This would probably be better served
> > as a separate television emulator.
>
> Yikes...Wow...Didn't intend for this to get so twisted or bent out of shape. As
> linked earlier, with the proper calculated formula applied for that Sony matrix,
> objectively, the setting without tint manipulation, provides a blue sky in SMB1.
>
> It is not a matter of "this looks kind of like how I remember it so it must be
> correct", but rather what is technical correct and sound when utilizing the 'Sony
> CXA2025AS US' decode matrix.
>
> Which again, was brought up as perhaps being a possible -option- under MAME for
> consoles and computers. It is not claiming anything else is inaccurate or incorrect,
> or the Sony_CXA2025AS US is the only right choice for NTSC US users, while everything
> else is wrong.
>
> Good grief...dropping this branch now. Beating a dead horse here while spinning my
> wheels...lol.