So now I'm wondering how many more TASes are out there like this. How many LOOK right but in fact rely on emulator bugs?
I'm also unsure about that anyone will come here and post a published TAS that probably relies on an emulator bug which would require the knowledge of the game and platform itself (cause I guess you are looking for known cases, not potential ones).
If the conditions are different, improving them and improving the run might fix the verification. If conditions used in that run are outright impossible, then it's pretty sad. Start from this post: http://tasvideos.org/forum/viewtopic.php?p=223361#223361
Impossible due hardware: - Famicom 2P controller has no start button, but the console accepts it. Example: [2840] NES Atlantis no Nazo by exposure in 02:20.12
So.... [2285] GBA Densetsu no Stafy "demo glitch" by jlun2 in 03:28.68 Ok, so the glitch is that if you restart when opening the menu, the temp save messes up, and you end up loading wierd things. Reset must be done on a lag frame, which means it's a hard reset, so the BIOS will play back every time the glitch is used. This movie isn't technically "impossible", but IF you do this on console, the last boss makes zero sense to restart over and over due to the BIOS playing back over and over. The glitch REQUIRES a hard reset since it occurs during a lag frame, so if this run were to be done on mGBA, it must beat the last boss "legit" simply due to the BIOS taking too long. tl;dr An updated TAS of it will be forced to be slower due to BIOS if reset; last boss cannot be glitched without significant slowdown. Also the run resets like 3 times to reach the boss, so the BIOS will be forced to playback more than once anyways. If it's any help, I can try remaking it in BizHawk and submitting it. I hope it doesn't cause too much issues. Edit: This same scenario also occurs for Dementium the Ward TAS, but for 1 single situation during the mouth room boss, where skipping the cutscene causes crashes after the chapter and forces a reset. The BIOS on a console would make this slower than simply viewing the cutscene.
EDIT: Another interesting case is [2821] A2600 River Raid by Lord_Tom in 1:22:47.90 The version of BizHawk used in this case has an error in the timer. The error is slight, but over an hour, it adds up to several seconds.
... I'm not sure if it's because the reset timing is different, or if it will work if subframe reset is implemented, but I'm not sure how to trigger the boss in the first room like the current run. I have no idea if it's truely impossible due to my lack of (assembly) knowledge, but I hope not. ... How much difference gameplay wise is that? Does it affect the RNG (or syncing)?
c346972718 A:00 X:1F Y:04 S:FD P:nvUBdIZC $D89B:A9 06 LDA #$06
c346972720 A:06 X:1F Y:04 S:FD P:nvUBdIzC $D89D:8D 06 C0 STA $C006 = #$06
c346972731 A:06 X:1F Y:04 S:FA P:nvUBdIzC $D4A8:48 PHA (NMI)
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c346975662 A:05 X:05 Y:00 S:F7 P:nvUBdIzc $D571:9D 00 C0 STA $C000,X @ $C005 = #$05
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c346975697 A:06 X:1F Y:04 S:FA P:nvUBdIzc $D582:40 RTI
c346975703 A:06 X:1F Y:04 S:FD P:nvUbdIzC $D8A0:85 42 STA $0042 = #$05D898: F0 BEQ $D89B A:00 X:1F Y:04 P:37 SP:FD Cy:346940446 nvTBdIZC
====NMI====
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D582: 40 RTI A:00 X:1F Y:04 P:26 SP:FA Cy:346943422 nvTbdIZc
D89B: A9 LDA #$06 A:00 X:1F Y:04 P:27 SP:FD Cy:346943428 nvTbdIZC
D89D: 8D STA $C006 A:06 X:1F Y:04 P:25 SP:FD Cy:346943430 nvTbdIzC
D8A0: 85 STA $42 A:06 X:1F Y:04 P:25 SP:FD Cy:346943434 nvTbdIzCExtreme botting was used to trigger this event. I remember millions of rerecords in the original submission. I disagree that having the bot hit an event 2 instructions too late is just an emulator glitch in principle. The event is right there, align objects differently and it will hit on a more accurate emulator.
The same applies to Half-Life TASes because of the way they are required to create and play.
EDIT: Another interesting case is [2821] A2600 River Raid by Lord_Tom in 1:22:47.90 The version of BizHawk used in this case has an error in the timer. The error is slight, but over an hour, it adds up to several seconds.
A commented disassembly by Thomas Jentzsch was helpful in figuring out how to manipulate enemy movements. Not sure why, but the memory addresses in the source don't match what's used in the emulator.
But, I think this discussion is better continued elsewhere (like the BunnymodXT thread).
http://tasvideos.org/userfiles/info/44858263236234342 I managed to trigger the warp on the mGBA core on the latest version of BizHawk, so at least the run's core route works on a more accurate emulator. Unfortunately, the glitch isn't quite the same; I'm forced to use the 2nd room instead, and for some reason visually, it appears different; on the vba run, I appear on the 2nd stage, but the game treats it as last. On BizHawk, the NPCs for the 2nd stage appear, but the background and all is still from the final stage. I'm not sure if it's because the reset timing is different, or if it will work if subframe reset is implemented, but I'm not sure how to trigger the boss in the first room like the current run. I have no idea if it's truely impossible due to my lack of (assembly) knowledge, but I hope not.
