Adobe Flash (AKA Shockwave Flash, Macromedia Flash): Python parsing library

SWF files are used by Adobe Flash (AKA Shockwave Flash, Macromedia Flash) to encode rich interactive multimedia content and are, essentially, a container for special bytecode instructions to play back that content. In early 2000s, it was dominant rich multimedia web format (.swf files were integrated into web pages and played back with a browser plugin), but its usage largely declined in 2010s, as HTML5 and performant browser-native solutions (i.e. JavaScript engines and graphical approaches, such as WebGL) emerged.

There are a lot of versions of SWF (~36), format is somewhat documented by Adobe.

File extension

swf

KS implementation details

License: CC0-1.0

References

This page hosts a formal specification of Adobe Flash (AKA Shockwave Flash, Macromedia Flash) using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.

The Python runtime library can be installed from PyPI:

python3 -m pip install kaitaistruct

Code

Parse a local file and get structure in memory:

data = Swf.from_file("path/to/local/file.swf")

Or parse structure from a bytes:

from kaitaistruct import KaitaiStream, BytesIO

raw = b"\x00\x01\x02..."
data = Swf(KaitaiStream(BytesIO(raw)))

After that, one can get various attributes from the structure by invoking getter methods like:

data.compression # => get compression

Python source code to parse Adobe Flash (AKA Shockwave Flash, Macromedia Flash)

swf.py

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import Enum
import zlib


if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 9):
    raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))

class Swf(KaitaiStruct):
    """SWF files are used by Adobe Flash (AKA Shockwave Flash, Macromedia
    Flash) to encode rich interactive multimedia content and are,
    essentially, a container for special bytecode instructions to play
    back that content. In early 2000s, it was dominant rich multimedia
    web format (.swf files were integrated into web pages and played
    back with a browser plugin), but its usage largely declined in
    2010s, as HTML5 and performant browser-native solutions
    (i.e. JavaScript engines and graphical approaches, such as WebGL)
    emerged.
    
    There are a lot of versions of SWF (~36), format is somewhat
    documented by Adobe.
    
    .. seealso::
       Source - https://open-flash.github.io/mirrors/swf-spec-19.pdf
    """

    class Compressions(Enum):
        zlib = 67
        none = 70
        lzma = 90

    class TagType(Enum):
        end_of_file = 0
        place_object = 4
        remove_object = 5
        set_background_color = 9
        define_sound = 14
        place_object2 = 26
        remove_object2 = 28
        frame_label = 43
        export_assets = 56
        script_limits = 65
        file_attributes = 69
        place_object3 = 70
        symbol_class = 76
        metadata = 77
        define_scaling_grid = 78
        do_abc = 82
        define_scene_and_frame_label_data = 86
    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.compression = KaitaiStream.resolve_enum(Swf.Compressions, self._io.read_u1())
        self.signature = self._io.read_bytes(2)
        if not self.signature == b"\x57\x53":
            raise kaitaistruct.ValidationNotEqualError(b"\x57\x53", self.signature, self._io, u"/seq/1")
        self.version = self._io.read_u1()
        self.len_file = self._io.read_u4le()
        if self.compression == Swf.Compressions.none:
            self._raw_plain_body = self._io.read_bytes_full()
            _io__raw_plain_body = KaitaiStream(BytesIO(self._raw_plain_body))
            self.plain_body = Swf.SwfBody(_io__raw_plain_body, self, self._root)

        if self.compression == Swf.Compressions.zlib:
            self._raw__raw_zlib_body = self._io.read_bytes_full()
            self._raw_zlib_body = zlib.decompress(self._raw__raw_zlib_body)
            _io__raw_zlib_body = KaitaiStream(BytesIO(self._raw_zlib_body))
            self.zlib_body = Swf.SwfBody(_io__raw_zlib_body, self, self._root)


    class Rgb(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.r = self._io.read_u1()
            self.g = self._io.read_u1()
            self.b = self._io.read_u1()


    class DoAbcBody(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.flags = self._io.read_u4le()
            self.name = (self._io.read_bytes_term(0, False, True, True)).decode(u"ASCII")
            self.abcdata = self._io.read_bytes_full()


    class SwfBody(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.rect = Swf.Rect(self._io, self, self._root)
            self.frame_rate = self._io.read_u2le()
            self.frame_count = self._io.read_u2le()
            if self._root.version >= 8:
                self.file_attributes_tag = Swf.Tag(self._io, self, self._root)

            self.tags = []
            i = 0
            while not self._io.is_eof():
                self.tags.append(Swf.Tag(self._io, self, self._root))
                i += 1



    class Rect(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.b1 = self._io.read_u1()
            self.skip = self._io.read_bytes(self.num_bytes)

        @property
        def num_bits(self):
            if hasattr(self, '_m_num_bits'):
                return self._m_num_bits

            self._m_num_bits = (self.b1 >> 3)
            return getattr(self, '_m_num_bits', None)

        @property
        def num_bytes(self):
            if hasattr(self, '_m_num_bytes'):
                return self._m_num_bytes

            self._m_num_bytes = (((self.num_bits * 4) - 3) + 7) // 8
            return getattr(self, '_m_num_bytes', None)


    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.record_header = Swf.RecordHeader(self._io, self, self._root)
            _on = self.record_header.tag_type
            if _on == Swf.TagType.define_sound:
                self._raw_tag_body = self._io.read_bytes(self.record_header.len)
                _io__raw_tag_body = KaitaiStream(BytesIO(self._raw_tag_body))
                self.tag_body = Swf.DefineSoundBody(_io__raw_tag_body, self, self._root)
            elif _on == Swf.TagType.set_background_color:
                self._raw_tag_body = self._io.read_bytes(self.record_header.len)
                _io__raw_tag_body = KaitaiStream(BytesIO(self._raw_tag_body))
                self.tag_body = Swf.Rgb(_io__raw_tag_body, self, self._root)
            elif _on == Swf.TagType.script_limits:
                self._raw_tag_body = self._io.read_bytes(self.record_header.len)
                _io__raw_tag_body = KaitaiStream(BytesIO(self._raw_tag_body))
                self.tag_body = Swf.ScriptLimitsBody(_io__raw_tag_body, self, self._root)
            elif _on == Swf.TagType.do_abc:
                self._raw_tag_body = self._io.read_bytes(self.record_header.len)
                _io__raw_tag_body = KaitaiStream(BytesIO(self._raw_tag_body))
                self.tag_body = Swf.DoAbcBody(_io__raw_tag_body, self, self._root)
            elif _on == Swf.TagType.export_assets:
                self._raw_tag_body = self._io.read_bytes(self.record_header.len)
                _io__raw_tag_body = KaitaiStream(BytesIO(self._raw_tag_body))
                self.tag_body = Swf.SymbolClassBody(_io__raw_tag_body, self, self._root)
            elif _on == Swf.TagType.symbol_class:
                self._raw_tag_body = self._io.read_bytes(self.record_header.len)
                _io__raw_tag_body = KaitaiStream(BytesIO(self._raw_tag_body))
                self.tag_body = Swf.SymbolClassBody(_io__raw_tag_body, self, self._root)
            else:
                self.tag_body = self._io.read_bytes(self.record_header.len)


    class SymbolClassBody(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.num_symbols = self._io.read_u2le()
            self.symbols = []
            for i in range(self.num_symbols):
                self.symbols.append(Swf.SymbolClassBody.Symbol(self._io, self, self._root))


        class Symbol(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._io.read_u2le()
                self.name = (self._io.read_bytes_term(0, False, True, True)).decode(u"ASCII")



    class DefineSoundBody(KaitaiStruct):

        class SamplingRates(Enum):
            rate_5_5_khz = 0
            rate_11_khz = 1
            rate_22_khz = 2
            rate_44_khz = 3

        class Bps(Enum):
            sound_8_bit = 0
            sound_16_bit = 1

        class Channels(Enum):
            mono = 0
            stereo = 1
        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.id = self._io.read_u2le()
            self.format = self._io.read_bits_int_be(4)
            self.sampling_rate = KaitaiStream.resolve_enum(Swf.DefineSoundBody.SamplingRates, self._io.read_bits_int_be(2))
            self.bits_per_sample = KaitaiStream.resolve_enum(Swf.DefineSoundBody.Bps, self._io.read_bits_int_be(1))
            self.num_channels = KaitaiStream.resolve_enum(Swf.DefineSoundBody.Channels, self._io.read_bits_int_be(1))
            self._io.align_to_byte()
            self.num_samples = self._io.read_u4le()


    class RecordHeader(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_code_and_length = self._io.read_u2le()
            if self.small_len == 63:
                self.big_len = self._io.read_s4le()


        @property
        def tag_type(self):
            if hasattr(self, '_m_tag_type'):
                return self._m_tag_type

            self._m_tag_type = KaitaiStream.resolve_enum(Swf.TagType, (self.tag_code_and_length >> 6))
            return getattr(self, '_m_tag_type', None)

        @property
        def small_len(self):
            if hasattr(self, '_m_small_len'):
                return self._m_small_len

            self._m_small_len = (self.tag_code_and_length & 63)
            return getattr(self, '_m_small_len', None)

        @property
        def len(self):
            if hasattr(self, '_m_len'):
                return self._m_len

            self._m_len = (self.big_len if self.small_len == 63 else self.small_len)
            return getattr(self, '_m_len', None)


    class ScriptLimitsBody(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.max_recursion_depth = self._io.read_u2le()
            self.script_timeout_seconds = self._io.read_u2le()