Class: WahWah::Riff::Chunk

Inherits:
Object
  • Object
show all
Includes:
LazyRead
Defined in:
lib/wahwah/riff/chunk.rb

Overview

4 bytes: an ASCII identifier for this particular RIFF or LIST chunk (for RIFF in the typical case, these 4 bytes describe the content of the entire file, such as “AVI ” or “WAVE”). rest of data: subchunks.

Constant Summary collapse

HEADER_SIZE = 
8
HEADER_FORMAT = 
"A4V"
HEADER_TYPE_SIZE = 
4

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from LazyRead

#data, prepended, #skip

Constructor Details

#initialize ⇒ Chunk

Returns a new instance of Chunk.



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# File 'lib/wahwah/riff/chunk.rb', line 27

def initialize
  @id, @size = @file_io.read(HEADER_SIZE)&.unpack(HEADER_FORMAT)
  return unless valid?

  @type = @file_io.read(HEADER_TYPE_SIZE).unpack1("A4") if have_type?
end

Instance Attribute Details

#id ⇒ Object (readonly)

Returns the value of attribute id.



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# File 'lib/wahwah/riff/chunk.rb', line 25

def id
  @id
end

#type ⇒ Object (readonly)

Returns the value of attribute type.



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# File 'lib/wahwah/riff/chunk.rb', line 25

def type
  @type
end

Instance Method Details

#size ⇒ Object 



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# File 'lib/wahwah/riff/chunk.rb', line 34

def size
  @size += 1 if @size.odd?
  have_type? ? @size - HEADER_TYPE_SIZE : @size
end

#valid? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/wahwah/riff/chunk.rb', line 39

def valid?
  !@id.empty? && !@size.nil? && @size > 0
end