Sonic Mania music swap script

music_hax.py

from struct import pack, unpack
from binascii import hexlify, unhexlify
from os.path import exists
from os import mkdir

mode = 1
filename = b"b15bad41162c48c8d5d3dbc533b0e1c8.ogg"
hashname = filename.split(".")[0]

if mode == 0: #extract
    if not exists("music"):
        mkdir("music")

    with open("Data.rsdk", "rb") as f:
        assert f.read(4) == b"RSDK"
        assert f.read(2) == b"v5"
        count = unpack("<H", f.read(2))[0]
        datas = []
        for i in range(count):
            datas.append(unpack("<16sII", f.read(24)))
        for data in datas:
            f.seek(data[1])
            size = data[2] & 0x7FFFFFFF
            if f.read(4) == b"OggS":
                with open("music/%s.ogg" % hexlify(data[0]), "wb") as o:
                    o.write(b"OggS" + f.read(size - 4)) #-4 = magic
                print("%s %08X %08X" % (hexlify(data[0]), data[1], data[2]))

elif mode == 1: #rebuild
    with open("Data.rsdk", "rb") as f:
        assert f.read(4) == b"RSDK"
        assert f.read(2) == b"v5"
        count = unpack("<H", f.read(2))[0]
        datas = []
        for i in range(count):
            datas.append(unpack("<16sII", f.read(24)))
        datas2 = []
        shift = 0
        keep = []
        for data in datas:
            if hexlify(data[0]) == hashname:
                keep = data
                oldsize = data[2] & 0x7FFFFFFF
                with open("music/%s.ogg" % hexlify(data[0]), "rb") as o:
                    o.seek(0, 2)
                    newsize = o.tell()
                shift = newsize - oldsize
                datas2.append([data[0], data[1], newsize])
            else:
                datas2.append([data[0], data[1] + shift, data[2]])
        with open("Data1.rsdk", "wb") as o:
            f.seek(0, 0)
            o.write(f.read(8))
            for data in datas2:
                o.write(data[0] + pack("<II", data[1], data[2]))
            f.seek(8 + (24 * len(datas2))) #9D40, not hardcoded, futureproof
            size = keep[1] - f.tell()
            o.write(f.read(size))
            with open("music/%s.ogg" % hexlify(keep[0]), "rb") as q:
                o.write(q.read())
            f.seek(keep[1] + (keep[2] & 0x7FFFFFFF))
            o.write(f.read())