Home Page Forums Other Emulator Message Boards Nestopia A few corrections

Database mistakes:
- Galactic Crusader (Bunch Games)
- Penguin & Seal (Sachen)
- Dudes with Attitude (AVE)
- Trolls on Treasure Island (AVE)

all have their mirroring wrong. It might also be a good idea to inform the user via a dialog box whenever the header settings of a ROM being loaded have been corrected from the database.

YUV palette:
The scale (0-255) is kind of nonsensical. Hue (chroma phase shift) should be in degrees from -45 (or so) to +45, like in the "Advanced" dialog. Also, the current "128" (center) setting is actually hue "-15", not "0". You might argue that "-15" looks "better" with a standard decoder, but that doesn't change the fact that the unmodified NES output is the "0" setting, not -15.

Saturation (chroma gain) should go from 0.0 to 2.0, with 1.0 being the "unchanged" setting (or maybe in percent instead, if you prefer that).

Brightness (RGB offset) should have 0 as the default (unchanged) setting, going from something like -1.0 to +1.0.

Contrast (RGB gain) should be moved out of the NTSC dialog into the YUV color dialog, having 1.0 as the default (unchanged) setting, going from 0.0 to 2.0, like saturation.

Advanced decoder settings:
The "canonical" G-Y angle is 227�?, not 236�?, at least per Sony service manual.

Thanks, I'll have them fixed.

The logfile will provide that info for now. It's disabled by default but can be enabled by the user in the 'Preferences' dialog.

Maybe for the HUE slider, but I don't see the point in changing the others. Having a mixed bag with different offsets and ranges will just look confusing and overcomplicated.

The idea was to have centered marks represent the default setting for the application which is not necessarily the same for a naked NES. The HUE slider is currently the only setting in which I've given this internal adjustment.

I put the contrast and sharpness sliders in the NTSC dialog to make it clear to the user that they're only applicable to the NTSC filter (unlike the others). I suppose I could move them somewhere else and grey them out when the NTSC filter is not in use, but why fix it if it ain't broken?

The "canonical" preset was something I calculated in order to make it produce the standard NTSC matrix and those values gave the closest match. There's currently a small error in it though, the G-Y gain should be set to '0.351' instead of '0.349'.

No problem, just make the "Default" button move the slider to "-15". But you should definitely indicate that this is not the "naked" NES output, for the purpose of having any "nonstandard" decoder values is precisely to make the picture look good without deviating from the zero hue.

I disagree; I think the values presented should have a practical meaning. Just going from 0 to 255 obfuscates what these controls actually do; you might as well remove the display of the values completely and go with "blind" sliders.
Instead, I believe that anyone with a minimal understanding of mathematics will find scales that have an *actual meaning* with regards to the result to be LESS confusing than just some arbitrary values from 0 to 255. Which is more confusing to you: "saturation is 50 percent", or "saturation is 64" ("64 what? sausages?", as my math teacher would say )?

"Contrast" adjustment (RGB gain, which means you just multiply RGB values with a factor) can be done whenever you're dealing with RGB values, not just with the NTSC filter. You're right about the sharpness control, which is why I have not mentioned that one.

Well, you got a point there. Percentage sliders are easier to deal with and will better reflect the math that goes behind, just as you say. I guess I was caught up thinking too much in base 16. It sorta becomes a habbit when you're messing with bits and bytes all day long.
In any case, here's what i did:

- Changed saturation, brightness and contrast into percentage sliders. 50 meaning no change.
- Moved the contrast slider out of the NTSC dialog and enabled it for use with plain palettes.
- Changed hue into a -45/+45�? slider. Default is 0�?.
- Changed the angles of the 'canonical' setting to reflect a standard matrix rotated by 15 degrees. This is for the better I think since it won't require the user to change the regular hue slider 15 marks back and forth whenever he/she wishes to change the predefined setting.

Unfortunately I don't have a point, because obviously I didn't express myself intelligibly enough.

A variable called "gain" (as in "RGB gain" --- colloquially called "contrast", or "chroma gain" --- colloquially called "saturation") is a factor in a product. Mathematically, for a product not to change an input variable's value, the factor must be 1.00 (100%), not 0.5 (50%).

On the other hand, a variable called "bias" or "offset" (as in "RGB offset" --- colloquially called "brightness") is an addend in a sum. Mathematically, for a sum not to change an input variable's value, the addend must be 0.00, not "50%" (percentages have no place in sums).

That's why Saturation and Contrast should be in percent, with 100% meaning "no change", and Brightness should be a plus/minus value, with 0 (zero) meaning "no change", all with regards to the mathematical explanation above.

That's even worse. "Canonical" means as defined by the standard. The standard defines R-Y/B-Y at 90�?/0�?, not 105�?/15�?.

I also don't understand why the user "has to" move the hue slider; it's not like the "-15" setting has a special meaning. The 0�? setting looks more greenish on the default decoder than on the consumer decoder; that should not be hidden from the user.

Fine, I'll change it.

So what do you suggest then? Which decoder and what hue should be set when the user starts the application for the first time or hits the "Default" button in the video dialog?

If you want it to *look* like the current release, "default" would be the canonical decoder (0/90) with Hue at -15�?, saturation/contrast at 100% (no change) and brightness at +/- 0.0 (no change), all being printed as such. The hue slider will be a little to the left (because 0�? would be the center), while all others, being at "no change", are centered.
Remember that all we've discussed so far is the way the settings are *printed* in the dialog box, not what kind of colors make good "defaults".
Just so there's no misunderstanding, here's the your "default" setting (hue=-15, standard decoder):

And here's how it would look at (hue=0):


Another suggestion: when in PAL mode, the hue should be "locked" to minus 15 degrees and the decoder shuold be "locked" to the canonical one. Because the PAL NES' output is actually shifted by 15 degrees from the NTSC NES, and PAL TVs all follow the decoder spec rigorously and don't allow the hue to be altered by the user.

Thanks for bearing with me.

If I put myself in the shoes of an average user, I want controls like a TV has. That means sliders (which some TVs display graphically on-screen) where the middle is normal. Personally I prefer the middle being zero and the extremes being -1.0 and 1.0 (or -10 or -100 and +10 or +100, if floating-point is too technical). I don't want to deal with the details of how they're implemented. Maybe some users desire a raw interface and would be accommodated by an expert interface.

It doesn't help that the interface to nes_ntsc is designed as I described above, making it a bit hard to specify raw values. I realize now that I could have taken a similar approach and provided a simplified and raw interface to the library. Though I think Nestopia uses its own palette generation code when not using the NTSC filter, so it's not all in my hands.

I'll have to read carefully over this thread to be sure I get the raw interface absolutely correct, since casual reading leaves me cross-eyed.

*If I put myself in the shoes of an average user, I want controls like a TV has.*


I second that.

Which the current method provides.