In the Fire Emblem community, people have figured out how to import tilesets from one game to the other, and magically their method also ports over all the metadata for the individual tiles, such as what graphics comprise what tile, what avoid/defense increases each tile may offer, the movement costs per tile, what background and palette to use, and other similar data.
But no one understands how this data is being ported over, or how to locate and edit this individual data. I suggest corruption, as most people in the Fire Emblem hacking community aren't familiar with or bothered enough to use an understanding of ASM to figure it out--but no one seemed to understand how helpful, and somewhat easy, corruption is for figuring out data.
If you're really open to the idea, I can link you over to help out some peeps. This would probably be more concentrated efforts than merely corrupting ROMs at-large to figure out where some data may or may not be.
I make no promises but post your links. What games and platforms are we talking about? What is currently known about this data? How are the porting it between games without understanding where the data is (with a tool that no one has the source code for, I assume)?
I find that having a good guess about the format of the data is key.
Having a good guess is essential with my method. I don't do it randomly. I usually pick a known value, like defense for a piece of armor, and then I find and replace every instance of that value in the ROM (or the save state) until I find that value.
That's what ROM/save-state corruption is. But there are so many opportunities to save time and effort. What I like to do is go halfway through the ROM/save-state, and then replace all down. If it loads and it doesn't change the value, then I've eliminated half the ROM/save-state as the possible data location in about a minute. Then I go halfway towards the beginning of the ROM/save-state and do it again, until I either find the value or it stops loading.
Not only is it fast and easy, it usually works. You often find other goodies too, literally random things. I found some addresses that effect available battlefields in Ogre Batte - TMOTBQ while searching for lycanthrope data that way (which was only half successful, since I only found half the lycanthrope data).
I really wish I had a hex editor developed specifically for ROM corruption.
Thank you creep.
What is the idea behind corruption?
I don't mind things being time consuming. I already expect that doing things the hard way will be needed if i hope to figure things out in the ROM. But at least I wanna eliminate things that were figured out already, or futile attempts from approaching something from the wrong angle.
Any advice on analyzing the CT SNES ROM? Or maybe good tools for the job?
I explained the idea behind ROM/save-state corruption above. With an SNES game your better off corrupting the ROM instead of save states. I don't know if a more accurate emulator is better for this task or not, so use whatever emulator you like (you want an editor that tolerates lots of bugs, because you'll make them as you corrupt swaths of the ROM).
If you wanted to find the item data for Chrono Trigger, then you have to make some educated guesses about how that data is stored based on available information. That info was found years ago, but for the sake of this example lets say that you only have the game itself to go on. Go to GameFAQs and download a guide that lists all the stats for equipment. Then download a hex editor (I recommend XVI32) and make a backup of your ROM. Then play the ROM until you reach a point where you can quickly open the menu and not be bothered. Make a save-state. Open your backup ROM with xvi32 and then use "count" to count the number of instances of the visible stats for each armor, until you find one that has the fewest occurrences.
This is important because fewer occurrences means less data for you to sort through.
Let's say that the armor with the most common value is "Iron Helm", which has a defense of 26. Convert 26 from decimal to hexadecimal and you get 0x1A.
Now you have some options. You can go about halfway through the ROM and replace down all occurrences of 0x1A with something else (let's say 0x2A). If this doesn't break the ROM and actually loads, then you can eliminate half the ROM as the location of that data if it doesn't change the defense of Iron Helm.
If it doesn't load, then you can go partway between where you began your search and the end of the ROM and try again until you pinpoint the place where the game breaks. Sometimes I do this and then I alter the address that breaks the game to something that doesn't break it, so I can continue to replace all down. In this case you could try changing that 0x1A to 0x19 or 0x1B.
But usually I give up on that, go to the beginning of the ROM, and start changing stuff there, one occurrence at a time. It helps if you keep very good notes in something like notepad or leafpad or your favorite plain text editor.
I wish that there was a hex editor that let your replace all occurrences of a value between any two addresses. I think Gemini's hex editor did that, but he said that you have to highlight the values to do that and that's a pain in the ass. I don't want to sit there for 10 minutes and highlight half the damn ROM, I want a text box where I can enter these values myself.
Searching for an occurrence, replacing it, loading the ROM/save-state, checking if it worked, writing it down, correcting the replaced occurrence and then repeating shouldn't take more than 90 seconds. It should not take more than 90 seconds because you WILL do this thousands of times before you are done. I went through 1,880 occurrences to find the item data in SaGa Frontier, and about 600 occurrences to find part of the Brave Up (or was it Regenerator?) reaction routine (though nobody ever expanded on what I did and eventually some ASM hackers duplicated - and completed - my efforts independently).
Ideally, any ROM hacking community should have a few ROM corrupters or data divers handy. They can find the easy stuff, and give the ASM hackers a good place to start looking for more difficult to find things.
Corruption is little more than replacing random parts of the data with junk.
I don't know if you'll be able to help, but I have what I think is probably a simplistic request.
In the English, European version of Tales of Eternia for PSP, there's a super annoying always on battery gauge that isn't present in the Japanese version of the game. It's ALWAYS present, even during loading sequences and cutscenes.
Could you see if you could find where it is, and disable it?
I've got a thread on the topic:
You could probably find that using Tile Molester. I don't want to go through the hassle of finding a PSP ROM and then finding a PSP emulator that works on my crappy computer. Open the ROM of that game with Tile Molester and fool around with the viewing settings until you get something that works. Since it's a PS1 game ported to the PSP, I'm guessing 2-dimensional; 4bpp, linear, reverse-order; and maybe 8 x 16.
I don't know what to do once you find it, but there are people here who could help you make it transparent, if you ask nicely. I imagine it would require you to replace the actual image of the battery with all zeros in the ROM, which should be easy once you find where it is.
This is a really basic question. At least half of ROM hacking is knowing what tool to use. I'm surprised no one recommended it for you.
Is there a sticky somewhere that tells what tools to look for for certain tasks?
Are there any programs to open up the ISO into its files and folders? You may be able to find the UI textures and blank out that battery icon specifically. That seems like the easiest method for what you want.
Are PSP disc images compressed?