interlaced artifacts

[turrican3]

Hi Tony,
There is some interlaced screen that still interlaced and blinking with all interlaced line mode.
team 17 logo, some demos (jesus was a demomaker), etc.. you have the screen blinking when the screen is interlaced

But it's possible to remove those blinks -> set the refresh to 1 frame out of 2, then no more blinks. could it be possible to add this option for interlaced screens ?? I think they use this possibility with pcsx2

like this it will display all frames but will cut it to 1 frame out of two when special interlaced mode is used because if i set it to 1 frame out of 2 frames then all the game is one frame out of two.

[Toni Wilen]

Not specific enough titles to find the exact program without wasting time. But I think at least some Team 17 logos are not using actual interlace, they just flicker by design.

[turrican3]

I'll try to make a list where i used 1/2 frame to stop blinking.
And i'll give you a fast way to test it.
Perhaps not today.
edited : jesus was a demomaker is just here : https://www.pouet.net/prod.php?which=4716
The picture which blink is attached. it's displayed after 2 minutes. the picture is hires single mode.
If you need more exemples i'll give you the full list.. I think there is even 1 or 2 full games

[Foebane]

Originally Posted by turrican3

The picture which blink is attached. it's displayed after 2 minutes. the picture is hires single mode.
If you need more exemples i'll give you the full list.. I think there is even 1 or 2 full games

I just ran this demo to test the image, and yes, there is flicker occurring that is unusual in that the even/odd lines of the image replace each other as opposed to being actually laced between each other, as they would on a CRT TV.

What do you mean by "single" mode, BTW?

In any case, I've seen this strong interlace effect before, in this prod here: https://www.pouet.net/prod.php?which=2341 - The slideshow consisting of raytraced objects and (sorry) exhibits this interlace issue, and I remember how it looked on my A1200 from the 1990s, and I was surprised how interlace could occur on a 320x256 screen (I think it was). I think the Jesus picture would look the same on real hardware, and as far as I can see, the flicker is purely by design.

[Toni Wilen]

Originally Posted by turrican3

I'll try to make a list where i used 1/2 frame to stop blinking.
And i'll give you a fast way to test it.
Perhaps not today.
edited : jesus was a demomaker is just here : https://www.pouet.net/prod.php?which=4716
The picture which blink is attached. it's displayed after 2 minutes. the picture is hires single mode.
If you need more exemples i'll give you the full list.. I think there is even 1 or 2 full games

Do not use KS 3.1. Use KS 3.0 or older.

KS 3.1 and program that takes over the display and tries to show interlaced mode without taking over the system: system fights back and switches back to non-laced, result is interlace mode that only shows even fields.

This is not the only program with this problem.

[DamienD]

Yup, more than a few times I've had that issue with numerous games and had to swap to KS 3.0

[turrican3]

thank you Toni,
i will get to sleep less stupid tonight.
Thanks

[Foebane]

Originally Posted by DamienD

Yup, more than a few times I've had that issue with numerous games and had to swap to KS 3.0

That might be fine if you're running the demo from WB, but what about running the demo from floppy disks, as in the example I cited? How do you choose the right WB then?

[DamienD]

Originally Posted by Foebane

That might be fine if you're running the demo from WB, but what about running the demo from floppy disks, as in the example I cited? How do you choose the right WB then?

Ke???

Changing KS ROMS when emulating is simple... what does it matter if running from floppy disk or hard drive when we are talking about A1200 3.0 / 3.1 KS ROMs???

...ok, if your on a real Amiga then it's a totally different story but that's not what you've asked.

[Foebane]

Originally Posted by DamienD

Ke???

Changing KS ROMS when emulating is simple... what does it matter if running from floppy disk or hard drive when we are talking about A1200 3.0 / 3.1 KS ROMs???

...ok, if your on a real Amiga then it's a totally different story but that's not what you've asked.

Sorry, wasn't thinking. As it is, it's late and I'm really tired, so I'll have a look tomorrow. Then again, having checked my available ROMs, there isn't a 3.0 one for A1200, so I guess I should use the A4000 one instead...?

[DamienD]

Originally Posted by Foebane

Then again, having checked my available ROMs, there isn't a 3.0 one for A1200, so I guess I should use the A4000 one instead...?

Of course there is a "A1200 - 3.0 KS ROM" in existence... what do you think came out before the 3.1 KS ROM on an A1200?

Here's what I have in WinUAE (which is more than I actually need / use); "A1200 - 3.0 KS ROM" highlighted in bold / red text:

CD32 extended ROM rev 40.60 (512k).rom
CD32 Full Motion Video Cartridge ROM rev 40.22 (256k).rom
CD32 Full Motion Video Cartridge ROM rev 40.30 (256k).rom
CD32 KS ROM v3.1 rev 40.60 (512k).rom
CD32 ROM (KS + extended) rev 40.60 (1024k).rom
CDTV extended ROM v1.00 (256k).rom
CDTV extended ROM v2.07 (256k).rom
CDTV-A570 extended ROM v2.30 (256k).rom
CDTV-CR extended ROM v3.32 (256k).rom
KS ROM v1.0 (A1000)(NTSC) (256k).rom
KS ROM v1.1 (A1000)(NTSC) rev 31.34 (256k).rom
KS ROM v1.1 (A1000)(PAL) rev 31.34 (256k).rom
KS ROM v1.2 (A1000) rev 33.166 (256k).rom
KS ROM v1.2 (A500,A1000,A2000) rev 33.180 (256k).rom
KS ROM v1.3 (A3000)(SK) rev 34.5 (256k).rom
KS ROM v1.3 (A500,A1000,A2000) rev 34.5 (256k).rom
KS ROM v1.4 (A3000) rev 36.16 (512k).rom
KS ROM v2.04 (A3000) rev 37.175 (512k).rom
KS ROM v2.04 (A500+) rev 37.175 (512k).rom
KS ROM v2.05 (A600) rev 37.299 (512k).rom
KS ROM v2.05 (A600HD) rev 37.300 (512k).rom
KS ROM v2.05 (A600HD) rev 37.350 (512k).rom
KS ROM v3.0 (A1200) rev 39.106 (512k).rom
KS ROM v3.0 (A4000) rev 39.106 (512k).rom
KS ROM v3.1 (A1200) rev 40.68 (512k).rom
KS ROM v3.1 (A3000) rev 40.68 (512k).rom
KS ROM v3.1 (A4000) rev 40.68 (512k).rom
KS ROM v3.1 (A4000) rev 40.70 (512k).rom
KS ROM v3.1 (A4000)(Cloanto) rev 40.68 (512k)
KS ROM v3.1 (A4000T) rev 40.70 (512k).rom
KS ROM v3.1 (A500,A600,A2000) rev 40.63 (512k).rom
KS ROM v3.X (A4000)(Cloanto) rev 45.57 (512k).rom

[Foebane]

Here's my collection of ROMs (from Amiga Forever 2012), somewhat different, and only one 3.0 ROM in all, for A4000 only it seems from when I tried it.

    amiga-boot-a1000.rom
    amiga-boot-a4091.rom
    amiga-boot-a590.rom
    amiga-crt-310-cd32-fmv.rom
    amiga-os-070.rom
    amiga-os-100.rom
    amiga-os-110.rom
    amiga-os-120.rom
    amiga-os-130-cdtv-ext.rom
    amiga-os-130.rom
    amiga-os-140-a3000.rom
    amiga-os-204.rom
    amiga-os-205.rom
    amiga-os-300.rom
    amiga-os-310-a1200.rom
    amiga-os-310-a3000.rom
    amiga-os-310-a4000.rom
    amiga-os-310-a500.rom
    amiga-os-310-cd32-ext.rom
    amiga-os-310-cd32.rom
    amiga-os-320-walker.rom
    amiga-os-3x0-a4000.rom
    aros-20110822-ext.rom
    aros-20110822.rom
    logica-dialoga-200.rom
    rom.key

I tried the 3.0 ROM on my A4000 config, running this prod: https://www.pouet.net/prod.php?which=4870

This is a slideshow that, on 3.1, always exhibited a nasty interlace flicker in most of the pictures. However, the flicker completely disappears under 3.0, and looks all the better for it!

My ROMs may be out of date, but this is a nice little tidbit of information to know. Thanks once again, Toni, and DamienD!

[Tomislav]

Here is list of known ROMs: https://cloanto.com/amiga/roms/
Some 3.1 and 3.X ROMs for which says 68000 and A600 actually can also go on A500, A500+, a1500 and A2000.

[mark_k]

At least for Jesus Was a Demomaker & Kickstart 3.1, a workaround which worked for me was to do Lacer 1 before running the demo. (Tested with WinUAE only, not real hardware.)

Does anyone feel like testing that with other non-track-loading demos which have similar interlace issues?

Edit to add: Same trick fixes the Corruption loading/title screen.

Not sure whether it's worth doing, but adding an option to have the WinUAE boot ROM code do the equivalent of Lacer 1 could be an easy way to "fix" games/demos where you can't easily run that command before booting. [For real-Amiga use, an option to do that could in theory be added to a program like Degrader.]

[mark_k]

Comment from graphics.library source relating to why the LOF bit may be written in the vertical blank interrupt routine:

* If the display mode just changed from Lace to non-laced, then the
* mode may be stuck in the ShortFrame mode. So make sure it's Long.
* However, don't do this if the system_beamcon0 LACE bit is set.

(Note typo: system_beamcon0 should be system_bplcon0)

The Lacer 1 command sets the LACE bit in system_bplcon0, hence avoiding the problem.