MiSTer FPGA Forum

Hi,

I have just noticed that the Arkanoid core has been updated to support custom aspect ratios. This is great as it is one of my favourite arcade games of all time! Many thanks to the developer!

Could someone please advise on the 'correct' aspect ratio for this game? Is it 4:3 the right one? I am asking that as I have already a 4:3 (1600x1200 ) monitor and I would have thought that 4:3 would be the perfect match for it.

Thanks a lot and my apologies if this is an obvious question

It's 200:171

@ flynnsbit,

That's great, many thanks for that. Much appreciated!

The core will be updated in the next few days to make 200:171 the default aspect ratio so you don't have to set a custom ratio anymore.

Ace wrote: ↑Fri Nov 20, 2020 3:57 am The core will be updated in the next few days to make 200:171 the default aspect ratio so you don't have to set a custom ratio anymore.

@Ace,
That's fantastic, many thanks for that!

Guys,
Just out of curiosity, could you please explain how this 200:171 has been calculated? As I am very keen to learn more I have been browsing a little bit and I stumbled across this web source:

http://pineight.com/mw/index.php?title=Dot_clock_rates

According to this web site Arkanoid has got a pixel aspect ratio of 45:44 which equates to 1.023 as opposed to 200:171 which equates to 1.169.

I would really appreciate if someone could shed some light and my apologies if I am missing the obvious!

Thanks a lot.

Alkadian wrote: ↑Sat Nov 21, 2020 11:10 am Guys,
Just out of curiosity, could you please explain how this 200:171 has been calculated? As I am very keen to learn more I have been browsing a little bit and I stumbled across this web source:

http://pineight.com/mw/index.php?title=Dot_clock_rates

According to this web site Arkanoid has got a pixel aspect ratio of 45:44 which equates to 1.023 as opposed to 200:171 which equates to 1.169.

I would really appreciate if someone could shed some light and my apologies if I am missing the obvious!

Thanks a lot.

That site references the PAR un-rotated. Here's how the math works:

45 * 256 = 11,520
44 * 224 = 9,856

However, we need to put it in TA-TAY mode (TATE) and then divide to get the display aspect ratio:

9,856 / 11, 520 = 0.855555555555

So in TATE mode, the display aspect ratio is 0.8555555555 to 1. Now lets upscale that to a usable MiSTer divider:

85.56 * 2 = 171.12
100 * 2 = 200

So the closest we can get is 200/171.

Update: I'm told the MiSTer divider has been expanded, so a new exact divider would be 90:77. However, I'm also told the core has to render 225 lines instead of 224. This means the new flawless divider is as follows:

64 tall by 55 wide. That's spot-on.

@Firebrandx,

That's great, many thanks for your so clear explanations! This is exactly what I was looking for. Thanks again!

No sweat. Although I'm embarrassed in that I forgot to reduce 900:770 to just simply 90:77. However, as Ace pointed out, there's a mid-scanline shift that forces the MiSTer to render 225 lines instead of 224, so here's the math breakdown for that:

45 * 256 = 11,520
44 * 225 = 9,900

9,900 / 11520 = 0.859375 to 1

Converting 0.859375 to a fraction the MiSTer can use = 64:55 (I use an online calculator to be lazy: https://www.calculatorsoup.com/calculat ... ulator.php )

Great,
Thanks again!