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Package File Format

Mgamerz edited this page Jun 3, 2024 · 4 revisions

The following is the package file format for the games in the Mass Effect Legendary Edition collection.

Offset Data type / size Description
0x0 0x4 / int Package Magic Number - 0x9E2A83C1
0x4 0x2 / short Unreal version (684)
0x6 0x2 / short Licensee version (171)
0x8 0x4 / int Full package header size (also known as 'Summary')
0xC 0x4 / int Folder name string length - always 5 in ME games
0x10 0x5 / char[] Folder name 'None' (including null terminator)
0x15 0x4 / int (bitmask) Package flags
0x19 0x4 / int Name table entry count
0x1D 0x4 / int Offset to start of name table (when decompressed)
0x21 0x4 / int Export entry count
0x25 0x4 / int Export metadata table offset (when decompressed)
0x29 0x4 / int Import entry count
0x2D 0x4 / int Import metadata table offset (when decompressed)
0x31 0x4 / int (Not used in Mass Effect games) Dependency table offset
0x35 0x4 / int (Not used in Mass Effect games) ImportExport guids table offset
0x39 0x4 / int (Not used in Mass Effect games) Import guids table offset
0x3D 0x4 / int (Not used in Mass Effect games) Export guids table offset
0x41 0x4 / int (Not used in Mass Effect games) Thumbnail table offset
0x45 0x10 / guid Package GUID - Used in replication
0x55 0x4 / int Number of package generations - always 1 in ME games
0x59 0x4 / int Generation[0]: Number of exports that were in the package at compile time
0x5D 0x4 / int Generation[0]: Number of names that were in the package at compile time
0x61 0x4 / int Generation[0]: Number of objects in under in this package at compile time (pre-cooked)
0x65 0x4 / int Engine version
0x69 0x4 / int CookedContent version
0x6D 0x4 / int Unknown
0x71 0x4 / int Unknown
0x75 0x4 / int (compression type) Type of compression used in this package
0x79 0x4 / int Number of compressed chunks to follow - once decompressed, the value will be zero
0x83 variable List of compressed chunks. If none, skip directly to the next item
After compressed chunks (ACC) 0x4 / int Package source
ACC + 0x4 0x4 / int Number of additional packages to cook along with this one - only used in level master files
ACC + 0x8 list List of unreal-style strings of packages this package also should cook
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