Overview
The PAK format appears to be encoded in little-endian format. A PAK archive consists of one or more archive files: a primary file, e.g. Main.pak, and perhaps a number of secondary files, e.g. Main_1.pak.
Manifest
The manifest only appears in the primary archive file. It consists of a header and a file table.
Header
The header is 0x15 (21) bytes long.
| Offset | Type | Size (bytes) | Field |
|---|---|---|---|
| 0x00 | uint32 | 4 | Format version number? Appears to be always 7. |
| 0x04 | uint32 | 4 | Offset of the start of the data section in bytes. This should be a multiple of 0x8000 (32 KiB). |
| 0x08 | uint32 | 4 | Number of archive files, including the primary. |
| 0x0C | uint32 | 4 | Length of the file table in bytes. This does not include the length of the header. |
| 0x10 | bool? | 1 | Unknown. Perhaps an "affects checksum" flag. |
| 0x11 | uint32 | 4 | Number of files in the archive. |
File table
Following the header is the file table as a sequence of file records. Each file record is 0x110 (272) bytes long.
| Offset | Type | Size (bytes) | Field |
|---|---|---|---|
| 0x000 | char* | 256 | Relative file path. |
| 0x100 | uint32 | 4 | Offset of the file within the archive file in bytes, not including the archive header if the file is in the primary archive file. This should be a multiple of 0x8000 (32 KiB). |
| 0x104 | uint32? | 4? | File size in bytes. |
| 0x108 | uint32? | 4? | Unknown. |
| 0x10C | uint32 | 4 | Index of the archive file the file is located in. 0 is the primary archive file. |
The remaining length between the end of the manifest and the start of the data section is padded with 0xAD bytes.
Data section
In the primary archive file, the data section follows the header. In the secondary archive files, the data section is the entire archive file. Files are laid out in the data section according to their record in the file table. Any space between the end of a file and the start of the next file is padded with 0xAD bytes.