Class: FilesHunter::Decoders::EBML

Inherits:
BeginPatternDecoder show all
Defined in:
lib/fileshunter/Decoders/EBML.rb

Constant Summary collapse

BEGIN_PATTERN_MKV = 
"\x1A\x45\xDF\xA3".force_encoding(Encoding::ASCII_8BIT)
DOCTYPE_ID_INT = 
642
SEGMENT_MATROSKA_ID = 
"\x18\x53\x80\x67".force_encoding(Encoding::ASCII_8BIT)
ACCEPTABLE_DOCTYPES = 
{
  'matroska' => :mkv,
  'webm' => :webm
}
VALID_ELEMENT_IDS =

List of possible elements, sorted by size. Taken from matroska.svn.sourceforge.net/viewvc/matroska/trunk/foundation_src/spectool/specdata.xml?view=markup

{
  1 => [
    "\x80".force_encoding(Encoding::ASCII_8BIT),
    "\x83".force_encoding(Encoding::ASCII_8BIT),
    "\x85".force_encoding(Encoding::ASCII_8BIT),
    "\x86".force_encoding(Encoding::ASCII_8BIT),
    "\x88".force_encoding(Encoding::ASCII_8BIT),
    "\x89".force_encoding(Encoding::ASCII_8BIT),
    "\x8e".force_encoding(Encoding::ASCII_8BIT),
    "\x8f".force_encoding(Encoding::ASCII_8BIT),
    "\x91".force_encoding(Encoding::ASCII_8BIT),
    "\x92".force_encoding(Encoding::ASCII_8BIT),
    "\x96".force_encoding(Encoding::ASCII_8BIT),
    "\x97".force_encoding(Encoding::ASCII_8BIT),
    "\x98".force_encoding(Encoding::ASCII_8BIT),
    "\x9a".force_encoding(Encoding::ASCII_8BIT),
    "\x9b".force_encoding(Encoding::ASCII_8BIT),
    "\x9c".force_encoding(Encoding::ASCII_8BIT),
    "\x9f".force_encoding(Encoding::ASCII_8BIT),
    "\xa0".force_encoding(Encoding::ASCII_8BIT),
    "\xa1".force_encoding(Encoding::ASCII_8BIT),
    "\xa2".force_encoding(Encoding::ASCII_8BIT),
    "\xa3".force_encoding(Encoding::ASCII_8BIT),
    "\xa4".force_encoding(Encoding::ASCII_8BIT),
    "\xa5".force_encoding(Encoding::ASCII_8BIT),
    "\xa6".force_encoding(Encoding::ASCII_8BIT),
    "\xa7".force_encoding(Encoding::ASCII_8BIT),
    "\xaa".force_encoding(Encoding::ASCII_8BIT),
    "\xab".force_encoding(Encoding::ASCII_8BIT),
    "\xae".force_encoding(Encoding::ASCII_8BIT),
    "\xaf".force_encoding(Encoding::ASCII_8BIT),
    "\xb0".force_encoding(Encoding::ASCII_8BIT),
    "\xb2".force_encoding(Encoding::ASCII_8BIT),
    "\xb3".force_encoding(Encoding::ASCII_8BIT),
    "\xb5".force_encoding(Encoding::ASCII_8BIT),
    "\xb6".force_encoding(Encoding::ASCII_8BIT),
    "\xb7".force_encoding(Encoding::ASCII_8BIT),
    "\xb9".force_encoding(Encoding::ASCII_8BIT),
    "\xba".force_encoding(Encoding::ASCII_8BIT),
    "\xbb".force_encoding(Encoding::ASCII_8BIT),
    "\xbf".force_encoding(Encoding::ASCII_8BIT),
    "\xc0".force_encoding(Encoding::ASCII_8BIT),
    "\xc1".force_encoding(Encoding::ASCII_8BIT),
    "\xc4".force_encoding(Encoding::ASCII_8BIT),
    "\xc6".force_encoding(Encoding::ASCII_8BIT),
    "\xc7".force_encoding(Encoding::ASCII_8BIT),
    "\xc8".force_encoding(Encoding::ASCII_8BIT),
    "\xc9".force_encoding(Encoding::ASCII_8BIT),
    "\xca".force_encoding(Encoding::ASCII_8BIT),
    "\xcb".force_encoding(Encoding::ASCII_8BIT),
    "\xcc".force_encoding(Encoding::ASCII_8BIT),
    "\xcd".force_encoding(Encoding::ASCII_8BIT),
    "\xce".force_encoding(Encoding::ASCII_8BIT),
    "\xcf".force_encoding(Encoding::ASCII_8BIT),
    "\xd7".force_encoding(Encoding::ASCII_8BIT),
    "\xdb".force_encoding(Encoding::ASCII_8BIT),
    "\xe0".force_encoding(Encoding::ASCII_8BIT),
    "\xe1".force_encoding(Encoding::ASCII_8BIT),
    "\xe2".force_encoding(Encoding::ASCII_8BIT),
    "\xe3".force_encoding(Encoding::ASCII_8BIT),
    "\xe4".force_encoding(Encoding::ASCII_8BIT),
    "\xe5".force_encoding(Encoding::ASCII_8BIT),
    "\xe6".force_encoding(Encoding::ASCII_8BIT),
    "\xe7".force_encoding(Encoding::ASCII_8BIT),
    "\xe8".force_encoding(Encoding::ASCII_8BIT),
    "\xe9".force_encoding(Encoding::ASCII_8BIT),
    "\xea".force_encoding(Encoding::ASCII_8BIT),
    "\xeb".force_encoding(Encoding::ASCII_8BIT),
    "\xec".force_encoding(Encoding::ASCII_8BIT),
    "\xed".force_encoding(Encoding::ASCII_8BIT),
    "\xee".force_encoding(Encoding::ASCII_8BIT),
    "\xf0".force_encoding(Encoding::ASCII_8BIT),
    "\xf1".force_encoding(Encoding::ASCII_8BIT),
    "\xf7".force_encoding(Encoding::ASCII_8BIT),
    "\xfa".force_encoding(Encoding::ASCII_8BIT),
    "\xfb".force_encoding(Encoding::ASCII_8BIT),
    "\xfd".force_encoding(Encoding::ASCII_8BIT)
  ],
  2 => [
    "\x42\x54".force_encoding(Encoding::ASCII_8BIT),
    "\x42\x55".force_encoding(Encoding::ASCII_8BIT),
    "\x42\x82".force_encoding(Encoding::ASCII_8BIT),
    "\x42\x85".force_encoding(Encoding::ASCII_8BIT),
    "\x42\x86".force_encoding(Encoding::ASCII_8BIT),
    "\x42\x87".force_encoding(Encoding::ASCII_8BIT),
    "\x42\xf2".force_encoding(Encoding::ASCII_8BIT),
    "\x42\xf3".force_encoding(Encoding::ASCII_8BIT),
    "\x42\xf7".force_encoding(Encoding::ASCII_8BIT),
    "\x43\x7c".force_encoding(Encoding::ASCII_8BIT),
    "\x43\x7e".force_encoding(Encoding::ASCII_8BIT),
    "\x44\x44".force_encoding(Encoding::ASCII_8BIT),
    "\x44\x61".force_encoding(Encoding::ASCII_8BIT),
    "\x44\x7a".force_encoding(Encoding::ASCII_8BIT),
    "\x44\x84".force_encoding(Encoding::ASCII_8BIT),
    "\x44\x85".force_encoding(Encoding::ASCII_8BIT),
    "\x44\x87".force_encoding(Encoding::ASCII_8BIT),
    "\x44\x89".force_encoding(Encoding::ASCII_8BIT),
    "\x45\x0d".force_encoding(Encoding::ASCII_8BIT),
    "\x45\x98".force_encoding(Encoding::ASCII_8BIT),
    "\x45\xa3".force_encoding(Encoding::ASCII_8BIT),
    "\x45\xb9".force_encoding(Encoding::ASCII_8BIT),
    "\x45\xbc".force_encoding(Encoding::ASCII_8BIT),
    "\x45\xbd".force_encoding(Encoding::ASCII_8BIT),
    "\x45\xdb".force_encoding(Encoding::ASCII_8BIT),
    "\x45\xdd".force_encoding(Encoding::ASCII_8BIT),
    "\x46\x5c".force_encoding(Encoding::ASCII_8BIT),
    "\x46\x60".force_encoding(Encoding::ASCII_8BIT),
    "\x46\x61".force_encoding(Encoding::ASCII_8BIT),
    "\x46\x62".force_encoding(Encoding::ASCII_8BIT),
    "\x46\x6e".force_encoding(Encoding::ASCII_8BIT),
    "\x46\x75".force_encoding(Encoding::ASCII_8BIT),
    "\x46\x7e".force_encoding(Encoding::ASCII_8BIT),
    "\x46\xae".force_encoding(Encoding::ASCII_8BIT),
    "\x47\xe1".force_encoding(Encoding::ASCII_8BIT),
    "\x47\xe2".force_encoding(Encoding::ASCII_8BIT),
    "\x47\xe3".force_encoding(Encoding::ASCII_8BIT),
    "\x47\xe4".force_encoding(Encoding::ASCII_8BIT),
    "\x47\xe5".force_encoding(Encoding::ASCII_8BIT),
    "\x47\xe6".force_encoding(Encoding::ASCII_8BIT),
    "\x4d\x80".force_encoding(Encoding::ASCII_8BIT),
    "\x4d\xbb".force_encoding(Encoding::ASCII_8BIT),
    "\x50\x31".force_encoding(Encoding::ASCII_8BIT),
    "\x50\x32".force_encoding(Encoding::ASCII_8BIT),
    "\x50\x33".force_encoding(Encoding::ASCII_8BIT),
    "\x50\x34".force_encoding(Encoding::ASCII_8BIT),
    "\x50\x35".force_encoding(Encoding::ASCII_8BIT),
    "\x53\x5f".force_encoding(Encoding::ASCII_8BIT),
    "\x53\x6e".force_encoding(Encoding::ASCII_8BIT),
    "\x53\x78".force_encoding(Encoding::ASCII_8BIT),
    "\x53\x7f".force_encoding(Encoding::ASCII_8BIT),
    "\x53\xab".force_encoding(Encoding::ASCII_8BIT),
    "\x53\xac".force_encoding(Encoding::ASCII_8BIT),
    "\x53\xb8".force_encoding(Encoding::ASCII_8BIT),
    "\x53\xb9".force_encoding(Encoding::ASCII_8BIT),
    "\x54\xaa".force_encoding(Encoding::ASCII_8BIT),
    "\x54\xb0".force_encoding(Encoding::ASCII_8BIT),
    "\x54\xb2".force_encoding(Encoding::ASCII_8BIT),
    "\x54\xb3".force_encoding(Encoding::ASCII_8BIT),
    "\x54\xba".force_encoding(Encoding::ASCII_8BIT),
    "\x54\xbb".force_encoding(Encoding::ASCII_8BIT),
    "\x54\xcc".force_encoding(Encoding::ASCII_8BIT),
    "\x54\xdd".force_encoding(Encoding::ASCII_8BIT),
    "\x55\xaa".force_encoding(Encoding::ASCII_8BIT),
    "\x55\xee".force_encoding(Encoding::ASCII_8BIT),
    "\x56\x54".force_encoding(Encoding::ASCII_8BIT),
    "\x57\x41".force_encoding(Encoding::ASCII_8BIT),
    "\x58\x54".force_encoding(Encoding::ASCII_8BIT),
    "\x58\xd7".force_encoding(Encoding::ASCII_8BIT),
    "\x61\xa7".force_encoding(Encoding::ASCII_8BIT),
    "\x62\x40".force_encoding(Encoding::ASCII_8BIT),
    "\x62\x64".force_encoding(Encoding::ASCII_8BIT),
    "\x63\xa2".force_encoding(Encoding::ASCII_8BIT),
    "\x63\xc0".force_encoding(Encoding::ASCII_8BIT),
    "\x63\xc3".force_encoding(Encoding::ASCII_8BIT),
    "\x63\xc4".force_encoding(Encoding::ASCII_8BIT),
    "\x63\xc5".force_encoding(Encoding::ASCII_8BIT),
    "\x63\xc6".force_encoding(Encoding::ASCII_8BIT),
    "\x63\xc9".force_encoding(Encoding::ASCII_8BIT),
    "\x63\xca".force_encoding(Encoding::ASCII_8BIT),
    "\x65\x32".force_encoding(Encoding::ASCII_8BIT),
    "\x66\x24".force_encoding(Encoding::ASCII_8BIT),
    "\x66\xa5".force_encoding(Encoding::ASCII_8BIT),
    "\x66\xbf".force_encoding(Encoding::ASCII_8BIT),
    "\x66\xfc".force_encoding(Encoding::ASCII_8BIT),
    "\x67\xc8".force_encoding(Encoding::ASCII_8BIT),
    "\x68\xca".force_encoding(Encoding::ASCII_8BIT),
    "\x69\x11".force_encoding(Encoding::ASCII_8BIT),
    "\x69\x22".force_encoding(Encoding::ASCII_8BIT),
    "\x69\x24".force_encoding(Encoding::ASCII_8BIT),
    "\x69\x33".force_encoding(Encoding::ASCII_8BIT),
    "\x69\x44".force_encoding(Encoding::ASCII_8BIT),
    "\x69\x55".force_encoding(Encoding::ASCII_8BIT),
    "\x69\xa5".force_encoding(Encoding::ASCII_8BIT),
    "\x69\xbf".force_encoding(Encoding::ASCII_8BIT),
    "\x69\xfc".force_encoding(Encoding::ASCII_8BIT),
    "\x6d\x80".force_encoding(Encoding::ASCII_8BIT),
    "\x6d\xe7".force_encoding(Encoding::ASCII_8BIT),
    "\x6d\xf8".force_encoding(Encoding::ASCII_8BIT),
    "\x6e\x67".force_encoding(Encoding::ASCII_8BIT),
    "\x6e\xbc".force_encoding(Encoding::ASCII_8BIT),
    "\x6f\xab".force_encoding(Encoding::ASCII_8BIT),
    "\x73\x73".force_encoding(Encoding::ASCII_8BIT),
    "\x73\x84".force_encoding(Encoding::ASCII_8BIT),
    "\x73\xa4".force_encoding(Encoding::ASCII_8BIT),
    "\x73\xc4".force_encoding(Encoding::ASCII_8BIT),
    "\x73\xc5".force_encoding(Encoding::ASCII_8BIT),
    "\x74\x46".force_encoding(Encoding::ASCII_8BIT),
    "\x75\xa1".force_encoding(Encoding::ASCII_8BIT),
    "\x78\xb5".force_encoding(Encoding::ASCII_8BIT),
    "\x7b\xa9".force_encoding(Encoding::ASCII_8BIT),
    "\x7d\x7b".force_encoding(Encoding::ASCII_8BIT),
    "\x7e\x5b".force_encoding(Encoding::ASCII_8BIT),
    "\x7e\x7b".force_encoding(Encoding::ASCII_8BIT),
    "\x7e\x8a".force_encoding(Encoding::ASCII_8BIT),
    "\x7e\x9a".force_encoding(Encoding::ASCII_8BIT),
    "\x7e\xa5".force_encoding(Encoding::ASCII_8BIT),
    "\x7e\xb5".force_encoding(Encoding::ASCII_8BIT)
  ],
  3 => [
    "\x22\xb5\x9c".force_encoding(Encoding::ASCII_8BIT),
    "\x23\x31\x4f".force_encoding(Encoding::ASCII_8BIT),
    "\x23\x83\xe3".force_encoding(Encoding::ASCII_8BIT),
    "\x23\xe3\x83".force_encoding(Encoding::ASCII_8BIT),
    "\x25\x86\x88".force_encoding(Encoding::ASCII_8BIT),
    "\x26\xb2\x40".force_encoding(Encoding::ASCII_8BIT),
    "\x2a\xd7\xb1".force_encoding(Encoding::ASCII_8BIT),
    "\x2e\xb5\x24".force_encoding(Encoding::ASCII_8BIT),
    "\x2f\xb5\x23".force_encoding(Encoding::ASCII_8BIT),
    "\x3a\x96\x97".force_encoding(Encoding::ASCII_8BIT),
    "\x3b\x40\x40".force_encoding(Encoding::ASCII_8BIT),
    "\x3c\x83\xab".force_encoding(Encoding::ASCII_8BIT),
    "\x3c\xb9\x23".force_encoding(Encoding::ASCII_8BIT),
    "\x3e\x83\xbb".force_encoding(Encoding::ASCII_8BIT),
    "\x3e\xb9\x23".force_encoding(Encoding::ASCII_8BIT)
  ],
  4 => [
    "\x10\x43\xa7\x70".force_encoding(Encoding::ASCII_8BIT),
    "\x11\x4d\x9b\x74".force_encoding(Encoding::ASCII_8BIT),
    "\x12\x54\xc3\x67".force_encoding(Encoding::ASCII_8BIT),
    "\x15\x49\xa9\x66".force_encoding(Encoding::ASCII_8BIT),
    "\x16\x54\xae\x6b".force_encoding(Encoding::ASCII_8BIT),
    "\x18\x53\x80\x67".force_encoding(Encoding::ASCII_8BIT),
    "\x19\x41\xa4\x69".force_encoding(Encoding::ASCII_8BIT),
    "\x1a\x45\xdf\xa3".force_encoding(Encoding::ASCII_8BIT),
    "\x1b\x53\x86\x67".force_encoding(Encoding::ASCII_8BIT),
    "\x1c\x53\xbb\x6b".force_encoding(Encoding::ASCII_8BIT),
    "\x1f\x43\xb6\x75".force_encoding(Encoding::ASCII_8BIT)
  ]
}

Instance Method Summary collapse

Methods inherited from BeginPatternDecoder

#find_segments

Methods inherited from FilesHunter::Decoder

#segments_found, #setup

Instance Method Details

#decode(offset) ⇒ Object 



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# File 'lib/fileshunter/Decoders/EBML.rb', line 251

def decode(offset)
  ending_offset = nil

  cursor = offset
  # Read the variable int for the header size
  header_size, vint_size = decode_vint(@data[cursor+4..cursor+11])
  cursor += 4 + vint_size
  progress(cursor)
  # Here we have header_size bytes for the header data.
  # Get the DocType
  max_header_cursor = cursor + header_size
  doc_type = nil
  while ((cursor < max_header_cursor) and (doc_type == nil))
    log_debug "=== @#{cursor} - Inspecting #{@data[cursor..cursor+20].inspect}"
    # Read next EBML segment
    segment_id, vint_size = decode_vint(@data[cursor..cursor+7])
    log_debug "=== @#{cursor} - Found ID #{segment_id}"
    cursor += vint_size
    # Read its size
    segment_size, vint_size = decode_vint(@data[cursor..cursor+7])
    cursor += vint_size
    if (segment_id == DOCTYPE_ID_INT)
      doc_type = @data[cursor..cursor+segment_size-1]
      log_debug "=== @#{cursor} - Found DocType: #{doc_type.inspect}"
    end
    cursor += segment_size
    progress(cursor)
  end
  invalid_data("@#{offset} - Unable to get the DocType from the EBML file") if (doc_type == nil)
  extension = ACCEPTABLE_DOCTYPES[doc_type]
  invalid_data("@#{offset} - Unknown DocType: #{doc_type}") if (extension == nil)
  # Make sure we consumed the header completely
  cursor = max_header_cursor
  # Now read the segment
  invalid_data("@#{cursor} - Invalid Segment ID") if (@data[cursor..cursor+3] != SEGMENT_MATROSKA_ID)
  found_relevant_data(extension)
  # Read segment size
  segment_size, vint_size = decode_vint(@data[cursor+4..cursor+11])
  log_debug "=== @#{cursor} - Found segment of size #{segment_size}"
  cursor += 4 + vint_size
  if (segment_size == 127)
    # The size is unknown
    # We have to make a deep decoding
    while (ebml_id_size = decode_ebml_id(cursor))
      # Read segment size
      segment_size, vint_size = decode_vint(@data[cursor+ebml_id_size..cursor+ebml_id_size+7])
      log_debug "=== @#{cursor} - Found segment #{segment_id} (size #{ebml_id_size}) of size #{segment_size} (size #{vint_size})"
      cursor += ebml_id_size + vint_size
      if (segment_size != 127)
        cursor += segment_size
        break if (cursor == @end_offset)
      end
      progress(cursor)
    end
  else
    cursor += segment_size
  end
  progress(cursor)
  ending_offset = cursor

  return ending_offset
end

#get_begin_pattern ⇒ Object 



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# File 'lib/fileshunter/Decoders/EBML.rb', line 247

def get_begin_pattern
  return BEGIN_PATTERN_MKV, { :offset_inc => 4 }
end