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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: CDE_MusiX on April 03, 2006, 09:53:49 AM

Title: A1200, interlaced screen, the screen "vibrate"
Post by: CDE_MusiX on April 03, 2006, 09:53:49 AM

Hello AMIGA fans, i've finally installed the HDD on the Amiga, and now i want to set the screen to the "interlaced high res. mode" (640x512x6). The operation succeeds, but the screen "vibrates", is "tremolante" when is in interlaced mode. Why happens? I have an AMIGA with a basic strutture (68020 processor, 3.0 ROM, 39.106 Kickstart, no Fast-RAM)

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: motorollin on April 03, 2006, 09:56:00 AM

What screen are you connecting it to? You will get this behaviour if the screen doesn't support interlaced screenmodes.

--
moto

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: CDE_MusiX on April 03, 2006, 09:58:54 AM

Is a Commodore 1074S (but i've to look better at home...)
It visualizes good the image of the interlaced mode, but it vibrate.

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: motorollin on April 03, 2006, 10:01:33 AM

Do non-interlaced screenmodes do the same thing?

--
moto

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: CDE_MusiX on April 03, 2006, 10:05:55 AM

no, cause for this problem, i'm using 640x256x6 non-interlaced res. mode

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: Piru on April 03, 2006, 10:16:44 AM

@CDE_MusiX

This is perfectly normal. It's interlace after all.

See http://en.wikipedia.org/wiki/Interlace

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: srg86 on April 03, 2006, 10:23:05 AM

hmm As far as I can see, with interlaced mode, as it takes 2 passes to fill the screen, it effectivley halves your refresh rate. Hence the flickering.

Graphics on a normal TV  boardcasts also has this horizontal shimmering as it is interlaced.

I love interlaced modes because of the picture quality, and even the DBLPAL/NTSC aren't quite as good. Trouble is that I hate the flickering :-(

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: bigdan on April 05, 2006, 08:08:28 AM

@CDE_MusiX : you could also try the MagicTV (http://www.aminet.net/search.php?query=magictv)  command available in aminet/util/wb to reduce the vibrates in interlaced modes... It's just a hack ;-P

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: mihcael on April 05, 2006, 08:14:34 AM

Lowering your brightness a tad will decrease the flickering (used to do this!)

changeing screen colors will aslo help, black and white are bad for this!

Use a program to change screen graphics so the windows have double thickness lines in them instead of single! (cant remember what program!)
 

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: amigakit on April 05, 2006, 09:21:41 AM

Another option is a flicker fixer (http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=414) which will eliminate the interlace flicker and also allow you to connect to a standard SVGA monitor.

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: spirantho on April 05, 2006, 09:31:39 AM

Some TFT monitors will display an interlaced composite signal too, without flicker. I know mine does. You can just use your A1200's composite out then - but of course you can't display DBLPAL/DBLNTSC modes without using the RGB->VGA connector as you can't do 31KHz over composite.

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: mihcael on April 05, 2006, 09:33:35 AM

Quote

Amigakit wrote:
Another option is a flicker fixer which will eliminate the interlace flicker and also allow you to connect to a standard SVGA monitor.

Allow or require?

I was always one for doing things for the least cost possible!

Title: Re: A1200, interlaced screen, the screen "vibrate"
Post by: SamuraiCrow on April 05, 2006, 05:44:50 PM

Getting rid of the interlace will require you to use a monitor with a higher sync and scan rate than what a 1084s monitor can do.  The 1084s uses television scan rates.