Ogg media container file: Python parsing library

Ogg is a popular media container format, which provides basic streaming / buffering mechanisms and is content-agnostic. Most popular codecs that are used within Ogg streams are Vorbis (thus making Ogg/Vorbis streams) and Theora (Ogg/Theora).

Ogg stream is a sequence Ogg pages. They can be read sequentially, or one can jump into arbitrary stream location and scan for "OggS" sync code to find the beginning of a new Ogg page and continue decoding the stream contents from that one.

File extension

["ogg", "ogv", "oga", "spx", "ogx"]

KS implementation details

License: CC0-1.0

References

This page hosts a formal specification of Ogg media container file 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 = Ogg.from_file("path/to/local/file.["ogg", "ogv", "oga", "spx", "ogx"]")

Or parse structure from a bytes:

from kaitaistruct import KaitaiStream, BytesIO

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

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

data.pages # => get pages

Python source code to parse Ogg media container file

ogg.py

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

from pkg_resources import parse_version
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO


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

class Ogg(KaitaiStruct):
    """Ogg is a popular media container format, which provides basic
    streaming / buffering mechanisms and is content-agnostic. Most
    popular codecs that are used within Ogg streams are Vorbis (thus
    making Ogg/Vorbis streams) and Theora (Ogg/Theora).
    
    Ogg stream is a sequence Ogg pages. They can be read sequentially,
    or one can jump into arbitrary stream location and scan for "OggS"
    sync code to find the beginning of a new Ogg page and continue
    decoding the stream contents from that one.
    """
    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.pages = []
        i = 0
        while not self._io.is_eof():
            self.pages.append(Ogg.Page(self._io, self, self._root))
            i += 1


    class Page(KaitaiStruct):
        """Ogg page is a basic unit of data in an Ogg bitstream, usually
        it's around 4-8 KB, with a maximum size of 65307 bytes.
        """
        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.sync_code = self._io.read_bytes(4)
            if not self.sync_code == b"\x4F\x67\x67\x53":
                raise kaitaistruct.ValidationNotEqualError(b"\x4F\x67\x67\x53", self.sync_code, self._io, u"/types/page/seq/0")
            self.version = self._io.read_bytes(1)
            if not self.version == b"\x00":
                raise kaitaistruct.ValidationNotEqualError(b"\x00", self.version, self._io, u"/types/page/seq/1")
            self.reserved1 = self._io.read_bits_int_be(5)
            self.is_end_of_stream = self._io.read_bits_int_be(1) != 0
            self.is_beginning_of_stream = self._io.read_bits_int_be(1) != 0
            self.is_continuation = self._io.read_bits_int_be(1) != 0
            self._io.align_to_byte()
            self.granule_pos = self._io.read_u8le()
            self.bitstream_serial = self._io.read_u4le()
            self.page_seq_num = self._io.read_u4le()
            self.crc32 = self._io.read_u4le()
            self.num_segments = self._io.read_u1()
            self.len_segments = [None] * (self.num_segments)
            for i in range(self.num_segments):
                self.len_segments[i] = self._io.read_u1()

            self.segments = [None] * (self.num_segments)
            for i in range(self.num_segments):
                self.segments[i] = self._io.read_bytes(self.len_segments[i])