gistfile1.py

import sys
from struct import unpack

class Replay:

    def __init__(self, filename):
        self.file = open(filename, "rb")

        self.versionbytes = 4
        self.headerbytes = 4


    def __IntFromBytes(self, bytes):
        """ Converts some bytes to an 32bit signed int """
        int = unpack("<L", bytes)[0]
        return int


    def Version(self):
        self.file.seek(0,0)
        self.raw_version = self.file.read(self.versionbytes)
        self.version = self.__IntFromBytes(self.raw_version)

        return self.version


    def HeaderLength(self):
        self.file.seek(self.versionbytes, 0)
        self.raw_headerlength = self.file.read(self.headerbytes)
        self.headerlength = self.__IntFromBytes(self.raw_headerlength)

        return self.headerlength


    def JSONHeader(self):
        self.file.seek((self.versionbytes + self.headerbytes), 0)
        self.jsonheader = self.file.read(self.HeaderLength())

        return self.jsonheader


filename = sys.argv[1]
replay = Replay(filename)

print replay.Version()
print replay.HeaderLength()
print replay.JSONHeader()