Class: WahWah::Flac::Block

Inherits:
Object
  • Object
show all
Includes:
LazyRead
Defined in:
lib/wahwah/flac/block.rb

Constant Summary collapse

HEADER_SIZE = 
4
HEADER_FORMAT = 
"B*"
BLOCK_TYPE_INDEX = 
%w[STREAMINFO PADDING APPLICATION SEEKTABLE VORBIS_COMMENT CUESHEET PICTURE]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from LazyRead

#data, prepended, #skip

Constructor Details

#initialize ⇒ Block

Returns a new instance of Block.



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# File 'lib/wahwah/flac/block.rb', line 14

def initialize
  # Block header structure:
  #
  # Length(bit)  Meaning
  #
  # 1            Last-metadata-block flag:
  #              '1' if this block is the last metadata block before the audio blocks, '0' otherwise.
  #
  # 7            BLOCK_TYPE
  #              0 : STREAMINFO
  #              1 : PADDING
  #              2 : APPLICATION
  #              3 : SEEKTABLE
  #              4 : VORBIS_COMMENT
  #              5 : CUESHEET
  #              6 : PICTURE
  #              7-126 : reserved
  #              127 : invalid, to avoid confusion with a frame sync code
  #
  # 24           Length (in bytes) of metadata to follow
  #              (does not include the size of the METADATA_BLOCK_HEADER)
  header_bits = @file_io.read(HEADER_SIZE).unpack1(HEADER_FORMAT)

  @last_flag = header_bits[0]
  @type = BLOCK_TYPE_INDEX[header_bits[1..7].to_i(2)]
  @size = header_bits[8..].to_i(2)
end

Instance Attribute Details

#type ⇒ Object (readonly)

Returns the value of attribute type.



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# File 'lib/wahwah/flac/block.rb', line 12

def type
  @type
end

Instance Method Details

#is_last? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/wahwah/flac/block.rb', line 46

def is_last?
  @last_flag.to_i == 1
end

#valid? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/wahwah/flac/block.rb', line 42

def valid?
  @size > 0
end