PoC decoder working \o/

This commit is contained in:
dreamer 2020-09-23 21:06:00 +02:00
parent 1863c5b243
commit 58ed95a305
5 changed files with 182 additions and 3 deletions

3
.gitmodules vendored Normal file
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[submodule "splimport/apetag"]
path = splimport/apetag
url = https://github.com/robertmuth/apetag.git

1
splimport/apetag Submodule

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Subproject commit 55f3d7a51946787df401573fc92698ed88a2cdee

67
splimport/apev2.ksy Normal file
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meta:
id: apev2
file-extension: apetag
endian: le
seq:
- id: tag
type: tag
types:
tag:
seq:
- id: header
type: header
size: 32
- id: frames
type: frame
repeat: expr
repeat-expr: header.item_count
- id: footer
type: footer
size: 32
header:
seq:
- id: preamble
contents: 'APETAGEX'
- id: version_number
type: u4
- id: tag_size
type: u4
- id: item_count
type: u4
- id: tag_flags
type: b32
- id: reserved
contents: [0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0]
size: 8
frame:
seq:
- id: item_size
type: u4
- id: item_flags
type: b32
- id: item_key
type: str
terminator: 0
encoding: UTF-8
- id: item_value
size: item_size
footer:
seq:
- id: preamble
contents: 'APETAGEX'
- id: version_number
type: u4
- id: tag_size
type: u4
- id: item_count
type: u4
- id: tag_flags
type: b32
- id: reserved
contents: [0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0]
size: 8

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splimport/apev2.py Normal file
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# This is a generated section! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
from pkg_resources import parse_version
from kaitaistruct import __version__ as ks_version, KaitaiStruct, KaitaiStream, BytesIO
if parse_version(ks_version) < parse_version('0.7'):
raise Exception("Incompatible Kaitai Struct Python API: 0.7 or later is required, but you have %s" % (ks_version))
class Apev2(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.tag = self._root.Tag(self._io, self, self._root)
class Tag(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self._raw_header = self._io.read_bytes(32)
io = KaitaiStream(BytesIO(self._raw_header))
self.header = self._root.Header(io, self, self._root)
self.frames = [None] * (self.header.item_count)
for i in range(self.header.item_count):
self.frames[i] = self._root.Frame(self._io, self, self._root)
self._raw_footer = self._io.read_bytes(32)
io = KaitaiStream(BytesIO(self._raw_footer))
self.footer = self._root.Footer(io, self, self._root)
class Header(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.preamble = self._io.ensure_fixed_contents(b"\x41\x50\x45\x54\x41\x47\x45\x58")
self.version_number = self._io.read_u4le()
self.tag_size = self._io.read_u4le()
self.item_count = self._io.read_u4le()
self.tag_flags = self._io.read_bits_int(32)
self._io.align_to_byte()
self.reserved = self._io.ensure_fixed_contents(b"\x00\x00\x00\x00\x00\x00\x00\x00")
class Frame(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.item_size = self._io.read_u4le()
self.item_flags = self._io.read_bits_int(32)
self._io.align_to_byte()
self.item_key = (self._io.read_bytes_term(0, False, True, True)).decode(u"UTF-8")
self.item_value = self._io.read_bytes(self.item_size)
class Footer(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.preamble = self._io.ensure_fixed_contents(b"\x41\x50\x45\x54\x41\x47\x45\x58")
self.version_number = self._io.read_u4le()
self.tag_size = self._io.read_u4le()
self.item_count = self._io.read_u4le()
self.tag_flags = self._io.read_bits_int(32)
self._io.align_to_byte()
self.reserved = self._io.ensure_fixed_contents(b"\x00\x00\x00\x00\x00\x00\x00\x00")

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import struct
from apev2 import Apev2
# apev2 spec: https://wiki.hydrogenaud.io/index.php?title=APEv2_specification
# parse dates from XLastPlayed and XLastScheduled from SPL. by brainsmoke:
# d=swap32(0x14a63351)
# Y,M,D,h,m,s = 1980+(d>>25), (d>>21)&0xf, (d>>16)&0x1f, (d>>11)&0x1f, (d>>5)&0x3f, (d<<1)&0x3f
# print(Y,M,D,h,m,s)
# for swapping endianness of a binary package
def swap32(i):
return struct.unpack("<I", struct.pack(">I", i))[0]
d=swap32(0x14a63351)
Y,M,D,h,m,s = 1980+(d>>25), (d>>21)&0xf, (d>>16)&0x1f, (d>>11)&0x1f, (d>>5)&0x3f, (d<<1)&0x3f
ape = Apev2.from_file('OMYG.apetag')
print(Y,M,D,h,m,s)
for item in ape.tag.frames:
key = item.item_key
value = item.item_value
# print(key, value)
if key == 'XLastPlayed':
hex = value.hex()
for i in range(0, len(hex), 8):
hex_chunk = "0x{}".format(hex[i: i+8])
d=swap32(int(hex_chunk, 16))
Y,M,D,h,m,s = 1980+(d>>25), (d>>21)&0xf, (d>>16)&0x1f, (d>>11)&0x1f, (d>>5)&0x3f, (d<<1)&0x3f
print(Y,M,D,h,m,s)