Well I've seen many doubts about this, specially in this GAF thread:
http://www.neogaf.com/forum/showthread.php?t=743872&page=5
I usually don't talk about stuff I'm not 100% I'll release, but it's ok if anyone wants to answer there too.
We are focusing on the following settings, that bring the highest compatibility and accuracy when playing the game:
-Merged ISO for PSP with CFW PRO @ 30fps.
Why PSP @ 30fps? Because the game is meant to be played on a PSP at that frame rate.
Why the Merged ISO? Because translating one ISO is way, but WAAAYYYY simpler than translating 2, in terms of romhacking.
Why PRO CFW? Because it's the only one that can play ISO's bigger than 2 GB with absolutely no problem.
There are many other possible settings, involving:
-Platform: it can be either PSP, PsVita, PS3, PC, or Android (guess IOS should work alright too, basically every platform where PPSSPP can be present).
-ISO Mode: Merged or separated.
-Native Frame rate: 60, 30 or 15 (7.5 fps is also possible but come on lol xD).
However, the patch we are working on, only aims at the settings initially stated. Any other combination is also possible but I simply don't have the hardware (or the time) to make sure everything works an intended. If I manage to get them, be sure I'll support as many combinations as I can.
Now, note that not all combinations make for a good gameplay, just imagine the game on a PSP @ 60 fps: I haven't even tried this, but the PSP lags sometimes with this game @ 30fps, so 60 would be too much for it to handle, most likely. On the other hand, the PS3 (which upscales the game up to 1080p) might be able to play the game at 60fps (I can't try).
By the by, you might be wondering what's up with the frame rates... I indeed have full control over the native fps counter of the game, so I can change the frame count for full speed. This is how I achieved so good performance in Android months ago: making the game run at 15fps, my phone/tablet only have to render half of the frames than a PSP, so while most user experiment half speed, I can optimize that to get full speed.
Of course the hardcore PC game would complain about choppy image in a 15fps game, but trust me, this is something you stop noticing within the first 5 minutes of gameplay (and in fact, absolutely nobody noticed it on my videos xD). So summarizing,
yes, I implemented an ASM internal frameskipping algorithm so the game can run full speed at 15fps, as part of the optimizations hacks. This is regarless of the platform. Of course, it doesn't make any sense playing at 15fps on a vita, psp, or PC (30 for PSP/Vita, and 60 for PC are good numbers, unless you have a low performance PC, in that case 15fps might even sound right; sure, if you have a super-duper Android device, it's possible to give it a shot at 60fps, that might work alright... in some years...).
But there is yet another problem in the equation: The UMD size. Being over 2GB's, only, and
ONLY the PRO CFW will be able to play it. There is no simple workaround for this right now, but there are 2 possible solution:
-Implement support to correctly address more than 2GB -> while this is possible for PPSSPP, I don't see it happening for Vita/PS3. In PSP it already happened with the inferno UMD driver (see why the PRO CFW is required?)
-Split the game back to 2 UMD's -> This takes a lot of work, and would be the way to go, but since I can't support the rest of settings (dont have a cfw vita/ps3), it would be crazy to spend all that time splitting one disc in two.
*Fun fact -> the internal ASM framskipping hack work for all Square Enix PSP games xD
~Sky