ISO creation and Rom enlargement (Alundra)

Post a topic about yourself to let others know your skills, hobbies, etc.
Post Reply
User avatar
Märchenwald
What is PSXDEV?
What is PSXDEV?
Posts: 1
Joined: Feb 20, 2021

ISO creation and Rom enlargement (Alundra)

Post by Märchenwald » February 20th, 2021, 3:14 am

Hi there!

First things first, let me introduce myself (since it's my first post here), I'm Märchenwald and I'm developing a lil level editor for a 1998 PSX game, The Adventures of Alundra (SLUS_00553/SLES_01198).

My soft deals with palettes edition, tilesets, dynamic objects, maps, sound, in bref, everything you need to edit levels in that game. For now, it's pretty far to be perfect and it's mostly a level "viewer" due to issues I encounter, but as you can see, it's a good beginning :
DREAMTRAVELER.png
My main problem is compression. Many many datas are compressed. My soft can extract raw datas, edit and eventualy recompress them, but the final size is pretty random.
Conclusion : I need to find a way to enlarge the ISO size (which seems to be a pain).

To exact files from the ISO, I use CDMage which works like a charm. You can use it to replace files in an original ISO, but they can't exceed original size, otherwise your edited file will be truncated..
I then tried to use mkpsxiso, but I'm pretty new to that and everything isn't clear to me.

When I tried to rebuild an ISO of the game from scratch with mkpsxiso then opened it with CDMage, I noticed all LBA changed (which is normal, I didn't precised the order of the files in my ISO, but I'm not sure how to do it)

So, I have some questions! 8-)

Q1 : Would mkisoxml help me to arrange files in my ISO the exact same way they are in the original?

Q2 : Is it easier/safer to edit the xml myself?

Q3 : Do I need to know something else to make that work?

Another thing, I found pretty all pointers that lead to datas in the game files. Most of them are in the main data header file, but some of them are located in the loader application used by the PS1 (LOADER.EXE). It contains all the pointers needed to access SEQ and VAB datas for the sound. Pretty logical since the music doesn't depend on the level in which you are. I tried to add a music I composed in SEQ and VAB in the sound file and added a pointer to the list in LOADER.EXE
When I did this, my files where truncated (normal since I did this with CDMage). I tested this with ePSXe and the ISO WORKED! But when I attached a debugger to the game and tried to search for my pointers list, the one I added wasn't here... I then assumed they were MORE pointers in the executable itself to access certain zones of data.
(Oh, yes, I didn't precised there were datas too in the LOADER.EXE, basicly some uncompressed graphics used when you launch the game, AND as it happens, my audio pointers)

So Q4 : Is it doable to edit a PSX application without corrupting it? Where am I the most likely to find pointers in my LOADER.EXE? I searched for them but found nothing, I supposed the format was different.
I found some 8bytes numbers starting with 0x80 that could be pointers. Do you think it's what I'm looking for? There are many of them but none seems to match with what I'm looking for...

Well.. Thanks in advance for your help! :D

EDIT : I tried to change the LBA of an enlarged file with TOC Changer.
Spoilers : The file is too big (nice)
Then, I tried to remove the dummy file which is know is NULL.NUL in the DATA folder.
I changed its size to 0 with TOC Changer, managed to replace it with an empty file with a same name, but CDMage won't save the new ISO file! >.<
That ISO creation is like a black box to me. I just can't figure out what's going on and fully understand how it works.
Very frustrating.. :roll:
You do not have the required permissions to view the files attached to this post.
Don't even consider calling me WoodTale

alundra
What is PSXDEV?
What is PSXDEV?
Posts: 1
Joined: Mar 06, 2021

Post by alundra » March 6th, 2021, 8:44 pm

I'm working on alundra to translate. can you help me to extract and reinsert 2 graphic text

Post Reply

Who is online

Users browsing this forum: No registered users and 5 guests