Re: [stella] My demo...

Subject: Re: [stella] My demo...
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Tue, 29 May 2001 15:15:28 +0200
Thomas wrote:
> For the different VCS colors we could try to do get as many samples as
possible from different VCS. Just find some common games (like PacMan, Space
Invaders, Pitfall!, ...) which nearly everybody owns and capture some
screens which show many well known colours.
> Then it would be quite easy to define an "average" RGB-triple for each

I think the colours in z26 are pretty acurate. But if someone can
provide better RGB values from his TV capture card, we'll try to
use them for improving the emulator. Quite some time ago I wrote
a little program that showed all 128 colours on the screen when you
pressed the joystick button. I think it's still available from Nick's
website. Even though I used it back then to try out the PAL colours
in PCAE, it would still work fine on a NTSC VCS.

Gonzalo wrote:
> Good idea... I can do it with two PAL-N 2600 (well, one is broken as I
> before)
> I have a question: If I make a PAL game, it will work on an NTSC system
> with colors changed and faster speed? or just won't work? I have the PELE
> game (football, soccer) and I play it on my 2600 with a red background, so
> think it is an NTSC game... in emulators I see the background green
> (obviously the right color), what is the problem?

The speed comes from the number of scanlines that you do per frame. NTSC
games usually do 262 lines per frame, which results in a rate of 60
frames per second. Games for the European PAL VCSs usually do 312 lines
per frame, which gets you 50 frames per second. If you write a PAL game
that does 50 frames per second, it will play at the same speed on any
VCS, be it PAL, NTSC or SECAM. However you would probably have to adjust
your NTSC TV in order to have the game syncronize to it.

The colour palette is different on all three models of the VCS. So
if you want to write a game, where the colours do matter, you would
probably be better off writing special versions for each TV-standard.

I don't know about PAL-N, but some South Americcan TV-standards
only use the PAL colour encoding, but keep the resolution and frame
rate from NTSC. You might have to take care of that, if you want
to be able to play your game on your own VCS.

BTW, z26 tries to detect the nessessary palette by counting the
number of scanlines that a game does per frame. If a game does
close to 262 lines, z26 will use the NTSC palette, and if a game
does close to 312 lines, z26 will use the PAL palette. You need
to keep that in mind when you are chosing the colours for your
game on the emulator only.

Manuel wrote:
> I'm using Z26 colors too. They simply match with my TV colors.
> Besides, when I had some colors selected for Gunfight on Z26
> it looked so crappy on StellaX that I never started it
> there again :-)

But the colours you are using in Gunfight are from the NTSC palette.
You'd be surprised how crappy they'd look on your TV. ;-)

Ciao, Eckhard Stolberg

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