hires flickering... sometimes

[Tony Landais]

I am sure the problem has been mentioned already but i can't find any thread...
Is it possible to avoid flickering in winuae when a game like Slamtilt swap to hires?

[Ironclaw]

Hmm, don't have the game right here now so can't test it, but I can't remember any flickering when slamtilt changed screenmode thingy (multiball I think).... tried playing in 640x512 or higher?....

[Tony Landais]

yes during the multiball the balls flick
I have to use opengl filtering for a normal speed and my resolution is higher than 640 512

[Toni Wilen]

Line doubling is enabled?

[Tony Landais]

it s doubled yes
hires works fine with Lionheart for exemple
...maybe because it s static
I have those lines
I tried with Vsync and without, several resolutions... but no success

[Tony Landais]

and I wanted to mention in full screen each time I press F12 for the configuration panel UAE switch to minimise and the panel disapear "only with slamtilt"... Works one time every 5 or 6 try.

[Toni Wilen]

Originally Posted by Tony Landais

I have those lines

Thats the usual effect when displaying interlaced video on progressive scan display device without (complex) image processing.

PC media players have same problem but they do have different algorithms that try to hide the problem. Maybe some can be made to work with UAE.. (with possible slowdown as usual..)

[whiteb]

I was gonna say before i saw Toni's last post, that it looks like its Interlaced.

[NoX1911]

But why is it field-based on an emulator? When you move the mouse you can see the interlace shift between lines on interlace resolutions. Doesn't the amiga work progressive internally (video buffer/memory)?

[Toni Wilen]

Originally Posted by NoX1911

Doesn't the amiga work progressive internally (video buffer/memory)?

Internal bitplane format does not really matter because copper can do its magic to separate it to odd and even fields easily.

ADDED: I think I misunderstood your question..

It may be possible to render the display progressively in interlaced modes but only if the screen is "static" (scrolling shouldn't matter but copper tricks in middle of screen will make it quite tricky..)

[NoX1911]

Originally Posted by Toni Wilen

Internal bitplane format does not really matter because copper can do its magic to separate it to odd and even fields easily.

But when does the picture get separated into fields? I mean, i don't really know how the blitter works but i think the picture, sprites and bobs (blitter objects) always remain progressive in memory. Those (interlace) fields are just a result of the method used to transfer the progressive picture to the display (that has to be fed with interlaced, so called field-based data) and may be avoidable with emulators.

It should be very similar to todays tv-out hardware of PCs. The 'primary surface' and the 'backbuffer' always remain progressive. Only the tv-out chip scans the odd and even lines (with a time difference of 1/50th second) of the (idependent) video buffer resulting in an interlaced output.

Maybe Agnus takes the part of those tv-chip function mentioned above (sending video data to monitor/display). From emulation point-of-view its correct but should be avoided to be emulated.

Maybe its possible to hack this and catch the video data directly.

Edit: On the other hand. If the blitter takes care about interlace output (and Agnus can create interlace based copper effects) at process time sending data directly to the display without any intermediate video memory a progressive picture would never be somewhere completely in memory. Then it would be impossible to grab/hack a progressive picture.

just a theory... i hope its understandable halfway.

[Toni Wilen]

I don't know how to explain it clearly but it does not work that way and it can't work that way.

You have to render the display line-by-line (or dma cycle by dma cycle) and you can't get 50 complete frames (including both odd and even frame) per second without complex tricks.

You can't compare Amiga to PC TV card or something similar. Copper, blitter, sprites etc.. makes it much more complex.

What you see in memory is usually not what you see in screen.. (except maybe when static game title screen is shown or application on WB screen)