Flickering when interlaced and non-interlaced highres screens "meet"

[Maren]

Here's how to reproduce it:

1. Set your Workbench 3.1's resolution to highres laced.
2. Set WinUAE's resolution to 640x512
3. Open DCTelnet 1.5
4. Click on the menu and drag the screen halfway down so you can see the Workbench behind.

The screen should now start flickering mad.

What to expect from a real Amiga? no clue, never tried this before on my A1200, but I can't help but wonder if this behavior can be improved in WinUAE.

Thanks.

[Coagulus]

I seem to remember this happening on my A500 too, if I dragged the workbench window down to start to reveal an interlaced screen the non interlaced workbench screen used to start vibrating too.

[Maren]

Hmm. It totally makes sense for a real amiga because anything interlaced would have to flicker, specially if PAL, and I suppose what's happenning here is that Workbench is displaying the progressive DCTelnet screen interlacedly so to make it suitable for it's screenmode, but nevermind, the whole screen stops flickering as you untick the "remove interlace artifacts" option, though the artifacts will be back on the Workbench, which was originally interlaced.

Hadn't seen WinUAE screen flicker in centuries, though


Edit: I tried changing DCTelnet's screenmode to highres-laced so the two screens would match, possibly avoiding a conflict, but turns out the flickering will still occur. Unticking the "remove interlace artifacts" option kills the flickering as efficiently as in the first example, but also introduces combing in DCTelnet, so now the whole screen gets combing.

[MagerValp]

While the Amiga is capable of switching video modes on each scanline, interlace applies to the whole frame, as interlace is accomplished by starting the whole frame half a scan line later, half of the time. If one visible screen has interlace enabled, all visible screens will flicker.

[Maren]

Can something be tweaked in WinUAE so to allow both screens to be displayed at the same time without flickering and without combing?

[Toni Wilen]

I don't know, I don't care until there is very quick test (like a statefile).

I am not going to install any extra software, adjust any settings if feature is something I don't really care. The usual

[Maren]

Well, if you have a functional WB3.1 installation (damn you if you don't ) all you need is DCTelnet (which comes with a handy installer) and that's about it, but if you simply don't find this to be interesting enough...

[Toni Wilen]

Originally Posted by Maren

Well, if you have a functional WB3.1 installation (damn you if you don't ) all you need is DCTelnet (which comes with a handy installer) and that's about it, but if you simply don't find this to be interesting enough...

No. Also there is no guarantee I have same settings.

[Maren]

This one should be much easier to reproduce. All you need is the CD32 kickstart roms.

1. What you see in the image above is what I always get when booting CD32 with "remove interlace artifacts" on. Lasts for a fraction of a second and the rest of the config doesn't seem to matter.

2. The combination of "remove interlace artifacts" and "vertical centering" is what actually creates the flickering, though only for certain host resolutions (e.g 640x512 but not 724x566) I know it is pointless to run something that uses an overscan high-res laced screen mode under 640x512, it obviously isn't enough, but this is necessary in order to reproduce the flickering which might be related to that previously mentioned (I accidentally overrode my hd image so I can't test any of the DCTelnet stuff right now)

3. A glitchy line at the bottom of the screen will also appear when combining "remove interlace artifacts" and "vertical centering" under certain host resolutions (e.g 724x566 but not 640x512) but this one I cannot record, it just doesn't show up in the screenshots/videos like the other glitch.

4. The state file doesn't work. A static CD32 screen is displayed for a few seconds then it goes black and nothing else happens, but I guess that's because there's nothing to save in there)

The attached config should trigger both the glitch from the image and the flickering. The log files will hopefully corroborate this

[Toni Wilen]

Originally Posted by Maren

4. The state file doesn't work. A static CD32 screen is displayed for a few seconds then it goes black and nothing else happens, but I guess that's because there's nothing to save in there)

This will be fixed in next beta.

Unfortunately I have to answr "not supported" to other problems. I really need standard WB split screen to confirm and test the problem.

[Maren]

Originally Posted by Toni Wilen

This will be fixed in next beta.

Unfortunately I have to answr "not supported" to other problems. I really need standard WB split screen to confirm and test the problem.

The CD32 problem I reported might as well be completely unrelated to the WB split screen one, and unlike the former, you don't even need to install or run anything in order to test it, just start WinUAE with the CD32 kickstart roms and mess with the settings as suggested in my previous post to see if the glitch can be successfully reproduced

[Toni Wilen]

Originally Posted by Maren

The CD32 problem I reported might as well be completely unrelated to the WB split screen one, and unlike the former, you don't even need to install or run anything in order to test it, just start WinUAE with the CD32 kickstart roms and mess with the settings as suggested in my previous post to see if the glitch can be successfully reproduced

Yeah but it is something that does not need to be supported by "interlace artifact" removal. More important cases first.

[Maren]

Originally Posted by Toni Wilen

Yeah but it is something that does not need to be supported by "interlace artifact" removal. More important cases first.

Ok, let's just forget about the interlace artifacts for a sec; can you at least confirm what I reported in paragraph number 2? that's some nasty flickering right there, not really an interlace artifact.

I was also thinking, if you really want to try the WB split screen flickering thing (which might not even be related to the CD32 one) would it be too complicated or unreliable to just install DCTelnet on a preinstalled Amiga Forever hd?