.big files are an archive format that was used in many game titles created by EA Studios.
The header has a fixed size of 16 bytes, following the table below:
| Offset | Bytes | Type | Name | Endianness |
|---|---|---|---|---|
| 0 | 4 | CHAR[] | FourCC | - |
| 4 | 4 | UINT32 | Size | LE |
| 8 | 4 | UINT32 | NumEntries | BE |
| 12 | 4 | UINT32 | OffsetFirst | BE |
- FourCC: Identifies the string as valid big archive. The string may either be "BIG4" or "BIGF", depending on the version.
- Size: The entire size of a big archive. Size of a single archive can not be greater than 2^32 bytes
- NumEntries: Number of files that were packed into this archive
- OffsetFirst: The offset inside the file to the first entry
After the header the follows a list with NumEntries elements, each entry looks the following:
| Offset | Bytes | Type | Name | Endianness |
|---|---|---|---|---|
| 0 | 4 | UINT32 | EntryOffset | BE |
| 4 | 4 | UINT32 | EntrySize | BE |
| 8 | 4 | CSTRING | EntryName | - |
- EntryOffset: specified the start of this entry inside the file (in bytes)
- EntrySize: the size of the specified entry
- EntryName: the name of this entry, read as a nullterminated string. The maximum length is limited ny the Windows MAX_PATH (which is 260).