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#!/usr/bin/env python3
# Python 3 code that will read, decompress, and then recompress the UE4 game
# save file that Astroneer uses.
#
# Though I wrote this for tinkering with Astroneer games saves, it's probably
# generic to the Unreal Engine 4 compressed saved game format.
import zlib
import sys
print()
filename = sys.argv[1]
with open(filename, 'rb') as compressed:
header1 = compressed.read(16)
print("Header: "+''.join('{:02X} '.format(x) for x in header1))
data_compressed1 = compressed.read()
data_decompressed1 = zlib.decompress(data_compressed1)
sz_in = len(data_compressed1)
sz_out = len(data_decompressed1)
with open(filename + '-raw', 'wb') as inflated:
inflated.write(data_decompressed1)
print("Inflated from {:d} (0x{:0x}) to {:d} (0x{:0x}) bytes".format(sz_in, sz_in, sz_out, sz_out))
with open(filename + '-z', 'wb') as deflated:
data_compressed2 = bytearray()
compress = zlib.compressobj(
6, # Compression level
zlib.DEFLATED, # default
(4+8), # Window size
zlib.DEF_MEM_LEVEL, # default
0 # Z_DEFAULT_STRATEGY
)
#compress = zlib.compressobj()
data_compressed2 += compress.compress(data_decompressed1)
data_compressed2 += compress.flush()
deflated.write(header1)
deflated.write(data_compressed2)
sz_in = len(data_decompressed1)
sz_out = len(data_compressed2)
print("Deflated from {:d} (0x{:0x}) to {:d} (0x{:0x}) bytes".format(sz_in,sz_in,sz_out,sz_out))
with open(filename + '-z', 'rb') as compressed:
header2 = compressed.read(16)
data_decompressed2 = zlib.decompress(compressed.read())
print()
if data_compressed1 == data_compressed2:
print("Compressed data matches!")
else:
print("Compressed data differs (but that may be ok)")
if data_decompressed1 == data_decompressed2:
print("Decompressed data matches!")
else:
print("Decompressed data differs (NOT GOOD)")
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