PSX Mode2/2352 disc geometry Confirmed
How the raw bytes of a Legend of Legaia disc image are organised, before any game-specific format gets involved. The disc is a standard PlayStation Mode2/Form1 CD: it's divided into 2352-byte sectors, but only a 2048-byte slice of each sector is actual file content - the rest is addressing and error-correction overhead. Everything else on this site starts from that 2048-byte view.
Overview
A CD image (.bin) is a flat run of sectors, addressed by LBA (logical block address - the sector number, counting from the start of the disc). "Mode2/2352" names the sector flavour PlayStation discs use: mode 2 of the CD-ROM XA standard, stored as full 2352-byte raw sectors rather than pre-stripped 2048-byte ones. Reading a file therefore means knowing which LBA it starts at and peeling the 2048 user-data bytes out of each sector.
Implementation: crates/iso/src/raw.rs.
Sector layout
| Bytes | Meaning |
|---|---|
| 0..12 | Sync pattern 00 FF FF FF FF FF FF FF FF FF FF 00 |
| 12..16 | Header (M:S:F address + mode byte) |
| 16..24 | Subheader (file/channel/submode/coding) |
| 24..2072 | User data (2048 bytes) |
| 2072..2352 | EDC + ECC error correction |
The iso crate's RawDisc::read_sector(lba) returns just the 2048-byte user data slice. read_user_data(lba, count, buf) reads a contiguous run.
const SECTOR_SIZE: usize = 2352;
const USER_DATA_OFFSET: usize = 24;
const USER_DATA_SIZE: usize = 2048;ISO9660 walk
On top of the sector layer sits ISO9660, the standard CD filesystem - it's what turns "sector 16" into named files and directories. Implementation: crates/iso/src/iso9660.rs. The layout is textbook:
- Primary Volume Descriptor at LBA 16.
- Root directory record at PVD offset 156.
- Each directory record begins with a length byte; records pad to even lengths.
The walker is iterative (not recursive) and yields stable-sorted file paths. The Legend of Legaia (USA) disc produces 45 files:
CDNAME.TXT DMY.DAT PROT.DAT SCUS_942.54 SYSTEM.CNF
MOV/MV1.STR ... MV6.STR
XA/XA1.XA ... XA21.XAAlmost everything interesting lives in just a few of these. PROT.DAT is the main asset archive - nearly every texture, model, script, and sound bank in the game is one of its numbered entries; see PROT.DAT TOC. SCUS_942.54 is the game's main executable. CDNAME.TXT is a developer-left name map for the archive's entries. MOV/MV*.STR are PSX MDEC video streams (the movies; delegate to public decoders like jPSXdec). XA/XA*.XA are XA-ADPCM streaming audio; crates/xa decodes the format spec but the on-disc files use a non-standard interleave. Reverse-engineering instructions: tooling/ghidra.md.