Homebrew Newbie Q: Should I apply AP fixes to properly emulate DS games?

weary_old_man

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Hi all,

Emulation newbie here. My old DSi XL recently died on me, so I've been toying with the idea of emulating some of the games I own. While falling down the rabbit hole that is NDS emulation, I came across the DS-Scene Rom Tool, which, for a few of my games, has options to apply AP (Anti-Piracy) fixes to the roms.

Are AP fixes something I should be applying to my roms for the purpose of emulation on something like DeSmuME? Or are those fixes primarily for the use in physical carts or with modified DS handhelds? I.e. do the emulators emulate accurately enough that the AP fixes aren't necessary? I suppose in theory, the AP fixed roms should also be able to emulated fine, but I'd like to avoid trying to fix something that isn't broken when possible.

Sorry if it sounds like I don't know what I'm talking about, because... well, I don't!

Thanks in advance for your input,
 

FAST6191

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If you stick with the vaguely current set of emulators then you should be fine. For the most part such tools are for weaker flash carts or flash carts that stopped getting updates before the games stopped coming.
It might also be possible for ROM hacks to trip the anti piracy but change the game so radically as to have the emulator's detection fail.

Some of the fixes might improve speed* or otherwise fix bugs and I am not sure all emulators will have those.

*the AP checks happened many times per second. Disabling them so they don't waste time with such things in turn saw several games be able to scroll menus faster and other such metrics over what a stock game would have seen. I have never seen any power usage contemplations for AP vs not (GBA has some things here https://www.dwedit.org/dwedit_board/viewtopic.php?id=480 ) but if you are on an emulator then it is likely a moot point.
 
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weary_old_man

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Hi FAST6191,

Thanks for the quick reply. That answers my question. Wow, I didn't know the AP tools checks occurred so frequently. I assumed if there was anything it would occur during startup or game related events (new games, story beats, etc).

You mentioned vaguely current emulators. Do you have a preference for DS emulation? It's not clear to me if DeSmuME is still being updated.

Thanks again!

Edit: Added question about preferred current emulators.
 
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FAST6191

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For most the big three are desmume (older but in many ways the high water mark*, not so much in the way of updates and forks** these days but also not like many new DS games come out and it was good when the DS was current), no$gba (has a nice debugger option for those doing hacks and cheats, quite good and updates still come but more on the DSi side of things) and melonDS is rising up (not sure it is quite there for me but actively updated and definitely something to watch out for). Afraid I don't really follow the multi emulator bundling projects like libretro/retroarch, though a little search just now says they don't really add anything and might be behind in some ways which is also what I think about most of the bundling projects in general.

*it gobbles a bit of resources on the PC, though anything vaguely current and even slightly with an eye towards gaming (so not one of those "64+200 gigs on the cloud" mini laptops) should be fine to get something playing on.

**it has some of the more interesting forks with https://github.com/TASVideos/desmume being something of the "officially" blessed fork and getting fixes at least (new features being a bit thin on the ground). Things like the high resolution emulation being among the more notable https://gbatemp.net/threads/hi-resolution-ds-emulation.364549/ from the game playing perspective (though there are other takes here, including it making it back into the official version), various hacker mods ( https://gbatemp.net/threads/unofficial-desmume-build-unused-memory-finder-tool.349332/ ) and some other things. It is not quite as radical as VBA saw back on the GBA, and unless you are taking up hacking and speedrunning there is little reason to go too far into them, but enough that I note it. Chances are if you are playing DS games on something that is not a Windows PC it will be desmume at its heart as well.

I should also note it was mostly later DS games with anti piracy that had all those checks. Most earlier efforts more or less were one and done during boot or soon thereafter with a simple block screen/failure to boot, a few more maybe made it a small demo, some did some subtle stuff (see Phantasy Star where it messed with drop rates) and later games then got hundreds of checks, maybe some more hidden checks (see the fun with COP the recruit I think it was), and some flash carts also upped their game as well (one of the major methods, see below 8000h reads, was sorted).
 

weary_old_man

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Thanks for the detailed reply, I appreciate it. I've been playing with desmume, and it looks like I managed to download the TASVideo fork (Zeromus) by working my way though the official desmume site. Not sure how I feel about high res fork! There's something charming about that DS pixel art, but maybe that's just nostalgia speaking.

I'll have to check out the other two emulators as well. I've heard of Melon but not No$Gba.

Thanks again for your assistance with these pretty basic questions.

Best,
 
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