Antiphona no Seikahime (PSP) .dat/.odi file compression

[Cargodin]

Hi there. I've got a quick question/I'd like some assistance and am throwing out a hangup I have on a game that I've been trying to peek into just for the hell of it. While I have luck getting into other games on PSP for the sake of perusing viscera, I can't even get through the first brick wall after using UMDGen, and this is the game I was hoping to do a mere text dump of, despite being the middle of a couple translation projects already so the priority is like... non-existent.



The odi is 397 kb and the .DAT is 620MB, and it's basically the melting pot for all of the game files. Opened it up in a Hex Editor already so it's not like the text was haphazardly thrown in (which I know better than to expect, but never hurts to try?).

Does anyone perhaps have any experience with this particular game?  I understand that odds are it's a custom format or it's compressed in some silly fashion. (the .odi seems to refer to other documents I can only assume are inside of the .dat)

Is this something that apparently sky's extractor could cover? On that particular side note, I've never been able to find a working download, but that's a different rant for a different day.

Thanks for your time to those who have read. Again, if anyone has any approaches for me to consider, I'd really appreciate the nods.

[Scio]

What's the header on both files? .odi is coming up as a XML + Graphics format here (OpenOffice).

[RetroHelix]

My first approach would be to open the odi file in a hexeditor and look for a filetable.

[henke37]

Yeah, this smells like a split archive, data in the big file and sub file positions in the smaller file.

[Cargodin]

Thanks you  guys for all of your responses! I really appreciate it. Here's the very top and very bottom of VOL1.odi, which shows off what I said earlier about the .odi being the head honcho of everything that goes down in the .DAT file orgy, and in comparison to other games, seems like a more simplified approach, but I could be incorrect on that. I don't really feel like the game was heavily compressed though.

Thoughts?

[Scio]

Looks like a simple list of .pmf (Playstation Movie Format.) files followed by their addresses.

EDIT: I've looked around Xentax and GBAtemp, and it seems there are already OpenBMS scripts (and a specific tool) to scan big files (your .DAT) for media files.
This guy made the specific tool: http://gbatemp.net/threads/final-fantasy-type-0-romhacking.340183/

[Cargodin]

Looks like a simple list of .pmf (Playstation Movie Format.) files followed by their addresses.

EDIT: I've looked around Xentax and GBAtemp, and it seems there are already OpenBMS scripts (and a specific tool) to scan big files (your .DAT) for media files.
This guy made the specific tool: http://gbatemp.net/threads/final-fantasy-type-0-romhacking.340183/

Do you mean the DJMAx tool? If so, I'm picking that up right now and will try it out. That will be a fun start for what it's worth, but I have already translated 7 out of the 9 songs on my own time as well, so I'm really just wanting to see the story/menu-related files, wherever in there they may be.