It does not work with Gran Turismo 4 Online Test Version (JP)

[PEACH-PIT]

It does not work with Gran Turismo 4 Online Test Version (JP).
If I unpack gt4.vol and repack it without editing, it generates a non-functional gt4.vol.
There is no problem to generate iso with cdvd_iml2iso.
If I regenerate the iso without touching the gt4.vol at all, it boots without problems.

[smellord]

same issue here! Tried exactly the same as you did. How is people still managing to make mods?
I modified the code of this repo slightly to add a toc export function and Analysing the TOC i noticed that repacking with the GT4_ONLINE flag the Page Offset value change drastically to a negative number:

here is a snippet of the TOC of the untouched online US file

NodeID, FullPath, Name, EntryType, ParentNode, Size, PageOffset, ModifiedDate

0, car\lod\ac__0014, ac__0014, CompressedFile, 24, 511434, 114229, 2006-04-21T17:01:46.0000000
0, car\lod\ac__0014.pat, ac__0014.pat, CompressedFile, 24, 82976, 114318, 2005-11-19T02:49:50.0000000
0, car\lod\acra0001, acra0001, CompressedFile, 24, 494216, 114328, 2005-11-19T03:02:59.0000000
0, car\lod\acra0001.pat, acra0001.pat, CompressedFile, 24, 14552, 114409, 2005-11-19T04:23:11.0000000
0, car\lod\acra0002, acra0002, CompressedFile, 24, 492616, 114412, 2005-11-19T01:26:11.0000000
0, car\lod\acra0002.pat, acra0002.pat, CompressedFile, 24, 11216, 114509, 2005-11-19T02:49:33.0000000
0, car\lod\acra0003, acra0003, CompressedFile, 24, 467784, 114511, 2005-11-19T03:02:59.0000000
0, car\lod\acra0003.pat, acra0003.pat, CompressedFile, 24, 10676, 114587, 2005-11-19T01:26:09.0000000
0, car\lod\acra0004, acra0004, CompressedFile, 24, 467144, 114589, 2005-11-19T04:23:11.0000000
0, car\lod\acra0004.pat, acra0004.pat, CompressedFile, 24, 21248, 114665, 2005-11-19T02:25:52.0000000
0, car\lod\acra0008, acra0008, CompressedFile, 24, 455432, 114669, 2005-11-19T00:59:01.0000000
0, car\lod\acra0008.pat, acra0008.pat, CompressedFile, 24, 2392, 114737, 2005-11-19T01:26:09.0000000
0, car\lod\acra0009, acra0009, CompressedFile, 24, 496712, 114738, 2005-11-19T02:49:32.0000000
0, car\lod\acra0009.pat, acra0009.pat, CompressedFile, 24, 18560, 114822, 2005-11-19T04:48:43.0000000
0, car\lod\acra0012, acra0012, CompressedFile, 24, 467208, 114825, 2005-11-19T02:12:46.0000000

here is the same snippet from the same file after extract and repack:

NodeID, FullPath, Name, EntryType, ParentNode, Size, PageOffset, ModifiedDate

0, car\lod\ac__0014, ac__0014, CompressedFile, 24, 511434, -8690, 2006-04-21T17:01:46.0000000
0, car\lod\ac__0014.pat, ac__0014.pat, CompressedFile, 24, 82976, -8601, 2005-11-19T02:49:50.0000000
0, car\lod\acra0001, acra0001, CompressedFile, 24, 494216, -8591, 2005-11-19T03:02:59.0000000
0, car\lod\acra0001.pat, acra0001.pat, CompressedFile, 24, 14552, -8511, 2005-11-19T04:23:11.0000000
0, car\lod\acra0002, acra0002, CompressedFile, 24, 492616, -8508, 2005-11-19T01:26:11.0000000
0, car\lod\acra0002.pat, acra0002.pat, CompressedFile, 24, 11216, -8411, 2005-11-19T02:49:33.0000000
0, car\lod\acra0003, acra0003, CompressedFile, 24, 467784, -8409, 2005-11-19T03:02:59.0000000
0, car\lod\acra0003.pat, acra0003.pat, CompressedFile, 24, 10676, -8333, 2005-11-19T01:26:09.0000000
0, car\lod\acra0004, acra0004, CompressedFile, 24, 467144, -8331, 2005-11-19T04:23:11.0000000
0, car\lod\acra0004.pat, acra0004.pat, CompressedFile, 24, 21248, -8255, 2005-11-19T02:25:52.0000000
0, car\lod\acra0008, acra0008, CompressedFile, 24, 455432, -8251, 2005-11-19T00:59:01.0000000
0, car\lod\acra0008.pat, acra0008.pat, CompressedFile, 24, 2392, -8183, 2005-11-19T01:26:09.0000000
0, car\lod\acra0009, acra0009, CompressedFile, 24, 496712, -8182, 2005-11-19T02:49:32.0000000
0, car\lod\acra0009.pat, acra0009.pat, CompressedFile, 24, 18560, -8098, 2005-11-19T04:48:43.0000000
0, car\lod\acra0012, acra0012, CompressedFile, 24, 467208, -8095, 2005-11-19T02:12:46.0000000

i think the issue is strictly related to that value as is the only one that changes

also the file size change for no reason when repacking!!

original gt4 online file: 2.24 GB (2,409,961,472 bytes)
untouched, repacked file: 2.28 GB (2,452,746,240 bytes)

i'm quite confused to why