497 lines
17 KiB
Python
497 lines
17 KiB
Python
""" MP4 Parser based on:
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http://download.macromedia.com/f4v/video_file_format_spec_v10_1.pdf
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@author: Alastair McCormack
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@license: MIT License
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"""
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import bitstring
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from datetime import datetime
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from collections import namedtuple
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import logging
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import six
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log = logging.getLogger(__name__)
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#log.addHandler(logging.NullHandler())
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log.setLevel(logging.WARN)
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class MixinDictRepr(object):
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def __repr__(self, *args, **kwargs):
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return "{class_name} : {content!r} ".format(class_name=self.__class__.__name__,
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content=self.__dict__)
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class MixinMinimalRepr(object):
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""" A minimal representaion when the payload could be large """
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def __repr__(self, *args, **kwargs):
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return "{class_name} : {content!r} ".format(class_name=self.__class__.__name__,
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content=self.__dict__.keys())
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class FragmentRunTableBox(MixinDictRepr):
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pass
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class UnImplementedBox(MixinDictRepr):
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type = "na"
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pass
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class MovieFragmentBox(MixinDictRepr):
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type = "moof"
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class MovieBox(MixinDictRepr):
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type = "moov"
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class BootStrapInfoBox(MixinDictRepr):
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type = "abst"
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@property
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def current_media_time(self):
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return self._current_media_time
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@current_media_time.setter
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def current_media_time(self, epoch_timestamp):
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""" Takes a timestamp arg and saves it as datetime """
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self._current_media_time = datetime.utcfromtimestamp(epoch_timestamp/float(self.time_scale))
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class FragmentRandomAccessBox(MixinDictRepr):
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""" aka afra """
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type = "afra"
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FragmentRandomAccessBoxEntry = namedtuple("FragmentRandomAccessBoxEntry", ["time", "offset"])
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FragmentRandomAccessBoxGlobalEntry = namedtuple("FragmentRandomAccessBoxGlobalEntry", ["time", "segment_number", "fragment_number", "afra_offset", "sample_offset"])
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pass
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class SegmentRunTable(MixinDictRepr):
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type = "asrt"
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SegmentRunTableEntry = namedtuple('SegmentRunTableEntry', ["first_segment", "fragments_per_segment"])
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pass
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class FragmentRunTable(MixinDictRepr):
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type = "afrt"
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class FragmentRunTableEntry( namedtuple('FragmentRunTableEntry',
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["first_fragment",
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"first_fragment_timestamp",
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"fragment_duration",
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"discontinuity_indicator"]) ):
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DI_END_OF_PRESENTATION = 0
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DI_NUMBERING = 1
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DI_TIMESTAMP = 2
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DI_TIMESTAMP_AND_NUMBER = 3
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def __eq__(self, other):
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if self.first_fragment == other.first_fragment and \
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self.first_fragment_timestamp == other.first_fragment_timestamp and \
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self.fragment_duration == other.fragment_duration and \
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self.discontinuity_indicator == other.discontinuity_indicator:
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return True
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def __repr__(self, *args, **kwargs):
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return str(self.__dict__)
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class MediaDataBox(MixinMinimalRepr):
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""" aka mdat """
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type = "mdat"
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class MovieFragmentHeader(MixinDictRepr):
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type = "mfhd"
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class ProtectionSystemSpecificHeader(MixinDictRepr):
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type = "pssh"
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BoxHeader = namedtuple( "BoxHeader", ["box_size", "box_type", "header_size"] )
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class F4VParser(object):
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@classmethod
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def parse(cls, filename=None, bytes_input=None, file_input=None, offset_bytes=0, headers_only=False):
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"""
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Parse an MP4 file or bytes into boxes
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:param filename: filename of mp4 file.
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:type filename: str.
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:param bytes_input: bytes of mp4 file.
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:type bytes_input: bytes / Python 2.x str.
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:param offset_bytes: start parsing at offset.
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:type offset_bytes: int.
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:param headers_only: Ignore data and return just headers. Useful when data is cut short
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:type: headers_only: boolean
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:return: BMFF Boxes or Headers
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"""
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box_lookup = {
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BootStrapInfoBox.type: cls._parse_abst,
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FragmentRandomAccessBox.type: cls._parse_afra,
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MediaDataBox.type: cls._parse_mdat,
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MovieFragmentBox.type: cls._parse_moof,
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MovieBox.type: cls._parse_moov,
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MovieFragmentHeader.type: cls._parse_mfhd,
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ProtectionSystemSpecificHeader.type: cls._parse_pssh
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}
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if filename:
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bs = bitstring.ConstBitStream(filename=filename, offset=offset_bytes * 8)
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elif bytes_input:
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bs = bitstring.ConstBitStream(bytes=bytes_input, offset=offset_bytes * 8)
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else:
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bs = bitstring.ConstBitStream(auto=file_input, offset=offset_bytes * 8)
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log.debug("Starting parse")
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log.debug("Size is %d bits", bs.len)
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while bs.pos < bs.len:
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log.debug("Byte pos before header: %d relative to (%d)", bs.bytepos, offset_bytes)
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log.debug("Reading header")
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try:
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header = cls._read_box_header(bs)
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except bitstring.ReadError as e:
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log.error("Premature end of data while reading box header")
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raise
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log.debug("Header type: %s", header.box_type)
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log.debug("Byte pos after header: %d relative to (%d)", bs.bytepos, offset_bytes)
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if headers_only:
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yield header
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# move pointer to next header if possible
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try:
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bs.bytepos += header.box_size
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except ValueError:
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log.warning("Premature end of data")
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raise
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else:
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# Get parser method for header type
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parse_function = box_lookup.get(header.box_type, cls._parse_unimplemented)
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try:
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yield parse_function(bs, header)
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except ValueError as e:
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log.error("Premature end of data")
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raise
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@classmethod
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def _is_mp4(cls, parser):
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try:
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for box in parser:
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return True
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except ValueError:
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return False
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@classmethod
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def is_mp4_s(cls, bytes_input):
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""" Is bytes_input the contents of an MP4 file
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:param bytes_input: str/bytes to check.
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:type bytes_input: str/bytes.
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:return:
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"""
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parser = cls.parse(bytes_input=bytes_input, headers_only=True)
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return cls._is_mp4(parser)
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@classmethod
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def is_mp4(cls, file_input):
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""" Checks input if it's an MP4 file
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:param input: Filename or file object
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:type input: str, file
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:param state: Current state to be in.
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:type state: bool.
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:returns: bool.
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:raises: AttributeError, KeyError
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"""
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if hasattr(file_input, "read"):
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parser = cls.parse(file_input=file_input, headers_only=True)
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else:
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parser = cls.parse(filename=file_input, headers_only=True)
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return cls._is_mp4(parser)
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@staticmethod
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def _read_string(bs):
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""" read UTF8 null terminated string """
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result = bs.readto('0x00', bytealigned=True).bytes.decode("utf-8")[:-1]
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return result if result else None
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@classmethod
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def _read_count_and_string_table(cls, bs):
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""" Read a count then return the strings in a list """
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result = []
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entry_count = bs.read("uint:8")
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for _ in six.range(0, entry_count):
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result.append( cls._read_string(bs) )
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return result
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@staticmethod
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def _read_box_header(bs):
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header_start_pos = bs.bytepos
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size, box_type = bs.readlist("uint:32, bytes:4")
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# box_type should be an ASCII string. Decode as UTF-8 in case
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try:
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box_type = box_type.decode('utf-8')
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except UnicodeDecodeError:
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# we'll leave as bytes instead
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pass
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# if size == 1, then this is an extended size type.
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# Therefore read the next 64 bits as size
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if size == 1:
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size = bs.read("uint:64")
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header_end_pos = bs.bytepos
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header_size = header_end_pos - header_start_pos
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return BoxHeader(box_size=size-header_size, box_type=box_type, header_size=header_size)
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@staticmethod
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def _parse_unimplemented(bs, header):
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ui = UnImplementedBox()
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ui.header = header
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bs.bytepos += header.box_size
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return ui
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@classmethod
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def _parse_afra(cls, bs, header):
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afra = FragmentRandomAccessBox()
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afra.header = header
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# read the entire box in case there's padding
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afra_bs = bs.read(header.box_size * 8)
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# skip Version and Flags
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afra_bs.pos += 8 + 24
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long_ids, long_offsets, global_entries, afra.time_scale, local_entry_count = \
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afra_bs.readlist("bool, bool, bool, pad:5, uint:32, uint:32")
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if long_ids:
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id_bs_type = "uint:32"
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else:
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id_bs_type = "uint:16"
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if long_offsets:
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offset_bs_type = "uint:64"
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else:
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offset_bs_type = "uint:32"
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log.debug("local_access_entries entry count: %s", local_entry_count)
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afra.local_access_entries = []
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for _ in six.range(0, local_entry_count):
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time = cls._parse_time_field(afra_bs, afra.time_scale)
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offset = afra_bs.read(offset_bs_type)
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afra_entry = \
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FragmentRandomAccessBox.FragmentRandomAccessBoxEntry(time=time,
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offset=offset)
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afra.local_access_entries.append(afra_entry)
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afra.global_access_entries = []
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if global_entries:
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global_entry_count = afra_bs.read("uint:32")
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log.debug("global_access_entries entry count: %s", global_entry_count)
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for _ in six.range(0, global_entry_count):
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time = cls._parse_time_field(afra_bs, afra.time_scale)
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segment_number = afra_bs.read(id_bs_type)
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fragment_number = afra_bs.read(id_bs_type)
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afra_offset = afra_bs.read(offset_bs_type)
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sample_offset = afra_bs.read(offset_bs_type)
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afra_global_entry = \
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FragmentRandomAccessBox.FragmentRandomAccessBoxGlobalEntry(
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time=time,
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segment_number=segment_number,
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fragment_number=fragment_number,
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afra_offset=afra_offset,
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sample_offset=sample_offset)
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afra.global_access_entries.append(afra_global_entry)
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return afra
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@classmethod
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def _parse_moof(cls, bootstrap_bs, header):
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moof = MovieFragmentBox()
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moof.header = header
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box_bs = bootstrap_bs.read(moof.header.box_size * 8)
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for child_box in cls.parse(bytes_input=box_bs.bytes):
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setattr(moof, child_box.type, child_box)
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return moof
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@classmethod
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def _parse_moov(cls, bootstrap_bs, header):
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moov = MovieBox()
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moov.header = header
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psshs = []
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box_bs = bootstrap_bs.read(moov.header.box_size * 8)
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for child_box in cls.parse(bytes_input=box_bs.bytes):
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if(child_box.type == "pssh"):
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psshs.append(child_box)
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else:
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setattr(moov, child_box.type, child_box)
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setattr(moov, "pssh", psshs)
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return moov
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@classmethod
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def _parse_mfhd(cls, bootstrap_bs, header):
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mfhd = MovieFragmentHeader()
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mfhd.header = header
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box_bs = bootstrap_bs.read(mfhd.header.box_size * 8)
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return mfhd
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@staticmethod
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def _parse_pssh(bootstrap_bs, header):
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pssh = ProtectionSystemSpecificHeader()
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pssh.header = header
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box_bs = bootstrap_bs.read(pssh.header.box_size*8)
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# Payload appears to be 8 bytes in.
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data = box_bs.hex[8:]
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pssh.system_id = data[:32]
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pssh.payload = data[40:]
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return pssh
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@classmethod
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def _parse_abst(cls, bootstrap_bs, header):
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abst = BootStrapInfoBox()
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abst.header = header
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box_bs = bootstrap_bs.read(abst.header.box_size * 8)
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abst.version, abst.profile_raw, abst.live, abst.update, \
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abst.time_scale, abst.current_media_time, abst.smpte_timecode_offset = \
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box_bs.readlist("""pad:8, pad:24, uint:32, uint:2, bool, bool,
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pad:4,
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uint:32, uint:64, uint:64""")
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abst.movie_identifier = cls._read_string(box_bs)
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abst.server_entry_table = cls._read_count_and_string_table(box_bs)
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abst.quality_entry_table = cls._read_count_and_string_table(box_bs)
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abst.drm_data = cls._read_string(box_bs)
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abst.meta_data = cls._read_string(box_bs)
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abst.segment_run_tables = []
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segment_count = box_bs.read("uint:8")
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log.debug("segment_count: %d" % segment_count)
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for _ in six.range(0, segment_count):
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abst.segment_run_tables.append( cls._parse_asrt(box_bs) )
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abst.fragment_tables = []
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fragment_count = box_bs.read("uint:8")
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log.debug("fragment_count: %d" % fragment_count)
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for _ in xrange(0, fragment_count):
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abst.fragment_tables.append( cls._parse_afrt(box_bs) )
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log.debug("Finished parsing abst")
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return abst
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@classmethod
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def _parse_asrt(cls, box_bs):
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""" Parse asrt / Segment Run Table Box """
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asrt = SegmentRunTable()
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asrt.header = cls._read_box_header(box_bs)
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# read the entire box in case there's padding
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asrt_bs_box = box_bs.read(asrt.header.box_size * 8)
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asrt_bs_box.pos += 8
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update_flag = asrt_bs_box.read("uint:24")
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asrt.update = True if update_flag == 1 else False
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asrt.quality_segment_url_modifiers = cls._read_count_and_string_table(asrt_bs_box)
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asrt.segment_run_table_entries = []
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segment_count = asrt_bs_box.read("uint:32")
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for _ in six.range(0, segment_count):
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first_segment = asrt_bs_box.read("uint:32")
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fragments_per_segment = asrt_bs_box.read("uint:32")
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asrt.segment_run_table_entries.append(
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SegmentRunTable.SegmentRunTableEntry(first_segment=first_segment,
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fragments_per_segment=fragments_per_segment) )
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return asrt
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@classmethod
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def _parse_afrt(cls, box_bs):
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""" Parse afrt / Fragment Run Table Box """
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afrt = FragmentRunTable()
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afrt.header = cls._read_box_header(box_bs)
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# read the entire box in case there's padding
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afrt_bs_box = box_bs.read(afrt.header.box_size * 8)
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afrt_bs_box.pos += 8
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update_flag = afrt_bs_box.read("uint:24")
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afrt.update = True if update_flag == 1 else False
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afrt.time_scale = afrt_bs_box.read("uint:32")
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afrt.quality_fragment_url_modifiers = cls._read_count_and_string_table(afrt_bs_box)
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fragment_count = afrt_bs_box.read("uint:32")
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afrt.fragments = []
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for _ in six.range(0, fragment_count):
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first_fragment = afrt_bs_box.read("uint:32")
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first_fragment_timestamp_raw = afrt_bs_box.read("uint:64")
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try:
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first_fragment_timestamp = datetime.utcfromtimestamp(first_fragment_timestamp_raw/float(afrt.time_scale))
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except ValueError:
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# Elemental sometimes create odd timestamps
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first_fragment_timestamp = None
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fragment_duration = afrt_bs_box.read("uint:32")
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if fragment_duration == 0:
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discontinuity_indicator = afrt_bs_box.read("uint:8")
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else:
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discontinuity_indicator = None
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frte = FragmentRunTable.FragmentRunTableEntry(first_fragment=first_fragment,
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first_fragment_timestamp=first_fragment_timestamp,
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fragment_duration=fragment_duration,
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discontinuity_indicator=discontinuity_indicator)
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afrt.fragments.append(frte)
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return afrt
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@staticmethod
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def _parse_mdat(box_bs, header):
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""" Parse afrt / Fragment Run Table Box """
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mdat = MediaDataBox()
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mdat.header = header
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mdat.payload = box_bs.read(mdat.header.box_size * 8).bytes
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return mdat
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@staticmethod
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def _parse_time_field(bs, scale):
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timestamp = bs.read("uint:64")
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return datetime.utcfromtimestamp(timestamp / float(scale) ) |