Subject: [stella] More on NTSC - PAL converting From: Eckhard_Stolberg@xxxxxxxxxxxxxxxxxxxxx (Eckhard Stolberg) Date: Thu, 20 Mar 1997 16:55:29 +0100 |
Hello there, a while back I have written a little NTSC - PAL guide. I have checked this subject a little further and I think it is a lot easyer than I thought. This post should have attatched a ZIP file with three little test programs in it. The first one, PALLINES.BIN, is for the loss of colour problem, some games have in PAL. I thought it was because of a wrong overall lines/Vblank lines ratio, but I was wrong. It seems that a program looses its colour signal only when it is doing an odd number of overall lines. It has no problem, if it does a even number of lines. To test this the PALLINES program allows you to change the number of overscan lines by moving the joystick up and down. It should display a blue background when the number of lines is even and loose the colour when the number is odd. The second one, TIME.BIN, is for the different refresh rates in PAL and NTSC which would cause the game to run at different speeds. The TIME program uses 262 lines, like a NTSC game and displays a clock. The seconds get increased every 60th frame. You can reset the timer by pressing the joystick button. I ran it on my PAL VCS and is seems, that the clock almost runs acurately. So to have your NTSC game display and play correctly on a PAL system it should: produce 262 or any even number of lines, make 3 of theese lines Vsync lines, and turn Vblank on in the overscan lines, because they would be still visible on the screen on PAL TVs. The only problem is the different colours. I asked you the last time to correct my description of the PAL colours, but got no response. Therefore I wrote this little colour test program, COLOUR.BIN. It displays the current colour and its hexvalue in white and in black on the top of the screen. On the bottom of the screen it displays the current hue in all 8 luminances on the left and the current luminance in all 16 hues on the right. By moving the stick up and down you can change the hue, by moving it left and right you can change the luminance. When the button is pressed all 128 colours are displayed on the screen with the current colour in the background. Can EVERYONE with a PAL system PLEASE run this program and send me discriptive names for all of the 16 hues, so I can see if mine were correct? BTW all programs use only 262 lines, so they can also be used on NTSC systems, but I don't think they are very usefull there. Thanks, Eckhard Stolberg
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PALTEST.ZIP
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