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Basics

There are various, standard compression types used across PDI games, most often using their own headers with a magic starting with FF F7. PS2ZIP is the most common.

Magic Name Compression Algorithm Games
FF F7 EE C5 PS2ZIP Inflate GT3 -> GT7
FF F7 F3 2F PDIZIP Inflate/ZLib GT Sport -> GT7
FF F7 ED 85 ZSTD ZIP (Tiny) ZSTD GT7
FF F7 97 2F ZSTD ZIP ZSTD GT7
FF F7 F3 2E ZSTD ZIP Chunk ZSTD GT7
FE FE 65 FA ? Oodle? GT7 (PS5)
FE FD DB 45 ? Oodle? GT7 (PS5)
FE FD B3 45 ? Oodle? GT7 (PS5)
FE F2 E5 FA ? Oodle? GT7 (PS5)

Warning

If you are using C#, do NOT use DeflateStream to create compression streams, it's been proven to have a few issues with games unable to read through them. You can use it to decompress, though.

Prefer using ICSharpCode.SharpZipLib for creating compressed streams.

PS2ZIP (FF F7 EE C5)

Applies to: GT3 and above

Field Offset Type Description
FF F7 EE C5 0x00 UInt Magic
Size Complement 0x04 Int Decompressed size (negated!)
Start of compressed data 0x08 Int Inflated data

PDIZIP (FF F7 F3 2F)

Applies to: GT Sport and above

Field Offset Type Description
FF F7 F3 2F 0x00 UInt Magic
expand_size 0x04 UInt Total decompressed size (negated!)
compressed_size 0x08 UInt Total compressed size (negated!)
fragment_size 0x0C UInt Size of one fragment
Fragments 0x10 Fragment[] Compressed fragments.

Fragment

Field Offset Type Description
fragment_expand_size 0x00 UInt Total decompressed size (negated!)
fragment_compressed_size 0x04 UInt Total compressed size (negated!)
Unknown 0x08 UInt ?
Start of compressed fragment data 0x10 byte[] Size of one fragment

ZSTD Zip Tiny (FF F7 ED 85)

Applies to: GT7

This format is normally not chunked.

Non-Chunked

Field Offset Type Description
FF F7 ED 85 0x00 UInt Magic
uncompressed_size 0x04 UInt Total decompressed size (negated!)
Start of compressed data 0x08 byte[] ZSTD compressed data

ZSTD Zip (FF F7 ED 85)

Applies to: GT7

Field Offset Type Description
FF F7 97 2F 0x00 UInt Magic
uncompressed_size_lo 0x04 UInt Total decompressed size (lower 32 bits)
uncompressed_size_hi 0x08 short Total decompressed size (upper 16 bits)
compressed_size_lo 0x0A UInt Total decompressed size (lower 32 bits)
compressed_size_hi 0x0E short Total decompressed size (upper 16 bits)
Unknown 0x10 byte[0x0C] N/A
Flags 0x1C UInt 0x01 = Fragmented

Tip

If fragmented, chunks may follow after. There is no chunk count, so check the magic accordingly.

ZSTD Chunk

These will all appear one after the other (including magic).

Field Offset Type Description
FF F7 F3 2E 0x00 UInt Magic
chunk_uncompressed_size 0x04 UInt Decompressed size of the chunk
chunk_compressed_size 0x08 UInt Compressed size of the chunk
crc_checksum 0x0C UInt CRC Checksum of the chunk

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