Safe areas for screen display

sack · 09 December 2011, 15:32

I'm not sure if this 100% qualifies as a coding question, but seeing as it's related to what I'm coding...

I have a standard 320x256 screen setup and using winUAE I knocked up a quick screen layout with a logo at the top, framebuffer flipping in the middle (not decided what to do with it yet), and a 16 line-high scrolltext at the bottom. in winUAE it looks okay - everything is where I'd expect it to be.

I just tried it on the A1200 I have here (connected to an old 14" TV through composite) and I'm seeing none of the scrolltext whatsoever. I can pull the wait out of my copperlist and pull the scroller up the screen and it's definitely there, I think it's just getting lost in the overscan.

Problem is I only have this one TV to try things out on really, but I want a screen layout where everything is reliably visible on a PAL Amiga.

So what are the safe areas that are reliably visible for a 320x256 screen?

KevG · 11 December 2011, 23:11

The eleventh commandment....

' Thou shalt not develope stuff in an emulator. Use a real Amiga. '

Bless you.

sack · 12 December 2011, 20:12

Well I was waiting for my 4GB CF and mouse to turn up. I've also found out that my startup/shutdown code needs some work.

Oh well... back to trawling the tutorial forums I go

Toni Wilen · 12 December 2011, 20:27

Use of real Amiga won't help in this problem if you use LCD TV or a scandoubler.

Old CRT TVs can have really bad overscan today because adjustments have drifted, capacitors dried etc. (Not that it wasn't much better originally..)

sack · 12 December 2011, 23:19

Nailed it now - the copper wait for the end of the NTSC area was wrong, but still allowed in winUAE. D'oh!

dc.w $ffdf,$fffe is the value I should've had. Looks like there's a broken tutorial out there someplace, but I can't remember which one I used now...

Now I can just pull things up a few lines until it seems to sit right on the screen

absence · 18 December 2011, 15:43

The safe areas of television are defined in the PAL and NTSC standards. I don't have the numbers in my head, but they're probably available online somewhere. Vertically you just count lines, but horizontally you have to calculate safe left and right using the pixel clock.

09 December 2011, 15:32	#1
sack Registered User Join Date: May 2010 Location: Rijswijk, the Netherlands Posts: 21	Safe areas for screen display I'm not sure if this 100% qualifies as a coding question, but seeing as it's related to what I'm coding... I have a standard 320x256 screen setup and using winUAE I knocked up a quick screen layout with a logo at the top, framebuffer flipping in the middle (not decided what to do with it yet), and a 16 line-high scrolltext at the bottom. in winUAE it looks okay - everything is where I'd expect it to be. I just tried it on the A1200 I have here (connected to an old 14" TV through composite) and I'm seeing none of the scrolltext whatsoever. I can pull the wait out of my copperlist and pull the scroller up the screen and it's definitely there, I think it's just getting lost in the overscan. Problem is I only have this one TV to try things out on really, but I want a screen layout where everything is reliably visible on a PAL Amiga. So what are the safe areas that are reliably visible for a 320x256 screen?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
On screen display like FPGAs machines	Leandro Jardim	request.UAE Wishlist	3	05 April 2013 20:35
native in screen display problem	turrican3	support.WinUAE	1	29 September 2012 05:22
Move on screen display	Leandro Jardim	request.UAE Wishlist	0	13 November 2011 02:49
Option to reposition 'Native on-screen display'	NoX1911	request.UAE Wishlist	2	27 February 2011 17:07
Problem with screen display.	KidCanary	support.WinUAE	3	02 December 2002 01:53

11 December 2011, 23:11	#2
KevG Banned Join Date: Jan 2009 Location: U.K. Posts: 93	The eleventh commandment.... ' Thou shalt not develope stuff in an emulator. Use a real Amiga. ' Bless you.

12 December 2011, 20:12	#3
sack Registered User Join Date: May 2010 Location: Rijswijk, the Netherlands Posts: 21	Well I was waiting for my 4GB CF and mouse to turn up. I've also found out that my startup/shutdown code needs some work. Oh well... back to trawling the tutorial forums I go

12 December 2011, 20:27	#4
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,570	Use of real Amiga won't help in this problem if you use LCD TV or a scandoubler. Old CRT TVs can have really bad overscan today because adjustments have drifted, capacitors dried etc. (Not that it wasn't much better originally..)

12 December 2011, 23:19	#5
sack Registered User Join Date: May 2010 Location: Rijswijk, the Netherlands Posts: 21	Nailed it now - the copper wait for the end of the NTSC area was wrong, but still allowed in winUAE. D'oh! dc.w $ffdf,$fffe is the value I should've had. Looks like there's a broken tutorial out there someplace, but I can't remember which one I used now... Now I can just pull things up a few lines until it seems to sit right on the screen

18 December 2011, 15:43	#6
absence Registered User Join Date: Mar 2009 Location: moon Posts: 373	The safe areas of television are defined in the PAL and NTSC standards. I don't have the numbers in my head, but they're probably available online somewhere. Vertically you just count lines, but horizontally you have to calculate safe left and right using the pixel clock.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)