[FR] Why was GSM 240p mode removed? [GSM]

[westonlast]

GSM .23 supports "NTSC-NI to Field-I" (240p) mode. Why is it no longer present?

This would be much better than hex editing ISOs to hard code 240p.

[rickgaiser]

Isn't this the "NTSC Non Interlaced" option?

[westonlast]

No. GSM has that one as a separate option. In both new and .23, that option displays only half of the screen.

[sp193]

The list of possible video modes here, were based on the ones from the last official, standalone version of GSM. You'll need to figure out why it was removed. And what's the difference between this and the actual non-interlaced NTSC/PAL (which seems to be 240P...) option.

[westonlast]

https://www.ps2-home.com/forum/viewtopic.php?t=7083

[westonlast]

https://www.ps2-home.com/forum/viewtopic.php?p=769#p771 (scroll up a bit from that post)

"Can both NTSC and PAL video modes be 'non- interlaced' (NTSC-NI and PAL-NI respectively)?"

There is a common homebrew technique to eliminate interlace flicker, and therefore called 'non-interlaced', even though that is technically untrue. The VSync period still has a non-integral number of HSync periods, so technically speaking the display is still interlaced, which is why TV sets display the mode description "480i" or "576i" in the popup that could appear at each incoming video mode change. But the appearance of the screen shows reduced flicker because odd and even frames repeat exactly the same 224 or 256 lines content, as opposed to normal interlace usage where the odd and even frames content differ so as to use a total of 448 or 512 lines together.

That "common homebrew technique" video mode "Non-Interlaced" is not equal to 240p.

The reason why this was removed was probably from confusion by people who don't use CRTs, thinking the two modes were the same. Unfortunate misinterpretation of documentation.

[sp193]

Thanks, but I think the question was referring to something else. I am not referring to any hackery, but the non-interlace setting that is implemented by the hardware. I.e. when set, you will see 240P video.

The answer references a "common homebrew technique", but that eludes me. Unless it is referring to switching the interlace option from FIELD (draw every other line) to FRAME (draw every line). The latter can half the vertical resolution, which sounds like what was described

[westonlast]

"Common homebrew technique" != "hackery." "Common homebrew technique" means a way to display 240 lines without scanlines and with reduced flickering because each pair of two 480 lines are the same.

If "common homebrew technique" is a "hack," then 240p mode in general is also a "hack." By that logic, all pre-PS2 era games were a "hack."

Hopefully now we're past that confusion of vocabulary,

What you have to understand is that the (non-"hack") hardware mode that you describe in isolation doesn't produce 240p. There are two parts to producing 240p:

1. The hardware mode needs to be correct.
2. The software framebuffer usage must be configured to correspond to that hardware mode.

The hardware mode is being set in a way that incorrectly corresponds to the framebuffer, so 240p doesn't work/isn't available/isn't supported by current GSM.

Take a look at the version .23 source code if this is unclear.

[LVNeptune]

'By that logic, all pre-PS2 era games were a "hack."'

This is accurate. http://junkerhq.net/xrgb/index.php?title=240p_video

[floppyD]

Any updates on this? Some games look much better at 240p, like Metal Slug Anthology. The current solution involves using GSM 0.23, setting it to "NTSC-NI to Field-I" then booting the game/homebrew you want, but it doesn't work with OPL at all since it just breaks on startup.

[oscarloria]

I have the same question, I play Ps2 on a CRT and there are many games (my favorite MvC2) that look incredible in 240p (NTSC-NI to Field-I), will it be possible to add this option in the next version of OPL? Thanks.