Class: Ogg::Page

Inherits:
Object
  • Object
show all
Defined in:
lib/ogginfo-rb.rb

Constant Summary collapse

CAPTURE = 
'OggS'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file) ⇒ Page

Returns a new instance of Page.



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# File 'lib/ogginfo-rb.rb', line 78

def initialize file
  @file = file

  # Header
  capture = file.read(CAPTURE.size)
  puts "Capture is not #{CAPTURE.inspect}" unless capture == CAPTURE

  version = file.read(1).unpack('C').first
  @page_type = file.read(1).unpack('C').first
  @granule_position = file.read(8).unpack('Q').first
  bitstream_serial_number = file.read(4).unpack('L').first
  page_sequence_number = file.read(4).unpack('L').first
  checksum = file.read(4).unpack('L').first
  page_segments = file.read(1).unpack('C').first
  @segment_table = file.read(page_segments).unpack('C*')

  # Content
  @data = StringIO.new '', 'w+'
  @segment_table.each do |n|
    @data.write file.read(n)
  end
  @data.close_write
  @data.rewind
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/ogginfo-rb.rb', line 75

def data
  @data
end

#granule_position ⇒ Object (readonly)

Returns the value of attribute granule_position.



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# File 'lib/ogginfo-rb.rb', line 76

def granule_position
  @granule_position
end

#page_type ⇒ Object (readonly)

Returns the value of attribute page_type.



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# File 'lib/ogginfo-rb.rb', line 76

def page_type
  @page_type
end

#segment_table ⇒ Object (readonly)

Returns the value of attribute segment_table.



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# File 'lib/ogginfo-rb.rb', line 76

def segment_table
  @segment_table
end

Class Method Details

.find_last_page(file) ⇒ Object 



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# File 'lib/ogginfo-rb.rb', line 121

def self.find_last_page file
			buffer_size = 1024
			pos = file.stat.size - buffer_size
			while pos > 0
file.seek pos, IO::SEEK_SET
sio = StringIO.new file.read(buffer_size)

# Find last page in buffer
    pg = page = Page.find_page(sio)
    while pg
      page = pg
      pg = pg.next_page
    end
return page if page
    
pos -= buffer_size * 2 - (CAPTURE.size - 1)
			end
			
			# This means that the Ogg file is not valid
			return nil
end

.find_page(file) ⇒ Object 



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# File 'lib/ogginfo-rb.rb', line 111

def self.find_page file
  buffer = file.read(CAPTURE.size)
  while buffer != CAPTURE
    return if file.eof?
    buffer = buffer[1..-1] << file.read(1)
  end
  file.pos -= CAPTURE.size
  return Page.new(file)
end

Instance Method Details

#continues? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ogginfo-rb.rb', line 103

def continues?
  return @segment_table.last == 255
end

#next_page ⇒ Object 



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# File 'lib/ogginfo-rb.rb', line 107

def next_page
  return Page.find_page(@file)
end