Class: Mp3file::ID3v2::Tag

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/mp3file/id3v2/tag.rb

Constant Summary collapse

FRAME_HEADER_NAME_REGEX = 
/[A-Z][A-Z0-9]{2,3}/

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io) ⇒ Tag

Returns a new instance of Tag.



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# File 'lib/mp3file/id3v2/tag.rb', line 14

def initialize(io)
  @header = Header.new(io)
  load_frames(io)
  used_bytes = @frames.inject(0) { |m, f| m += f.size }
  @unused_bytes = @header.tag_size - used_bytes
end

Instance Attribute Details

#frames ⇒ Object (readonly)

Returns the value of attribute frames.



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# File 'lib/mp3file/id3v2/tag.rb', line 10

def frames
  @frames
end

#header ⇒ Object (readonly)

Returns the value of attribute header.



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# File 'lib/mp3file/id3v2/tag.rb', line 10

def header
  @header
end

#unused_bytes ⇒ Object (readonly)

Returns the value of attribute unused_bytes.



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# File 'lib/mp3file/id3v2/tag.rb', line 10

def unused_bytes
  @unused_bytes
end

Instance Method Details

#get_next_frame_header(data, offset) ⇒ Object 



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# File 'lib/mp3file/id3v2/tag.rb', line 43

def get_next_frame_header(data, offset)
  md = data.match(FRAME_HEADER_NAME_REGEX, offset)

  while md
    frame_offset = md.begin(0)
    io = StringIO.new(data[frame_offset, 32])
    frame = FrameHeader.new(io, self)

    if frame.frame_id.to_s =~ FRAME_HEADER_NAME_REGEX
      return [ frame_offset, frame ]
    else
      frame_offset = md.end(0) + 1
      md = data.match(FRAME_HEADER_NAME_REGEX, frame_offset)
    end
  end

  [ nil, nil ]
end

#load_frames(io) ⇒ Object 



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# File 'lib/mp3file/id3v2/tag.rb', line 21

def load_frames(io)
  @frames = []

  data = io.read(@header.tag_size)
  data.force_encoding("ASCII-8BIT")
  offset = 0

  loop do
    frame_offset, frame = get_next_frame_header(data, offset)
    if frame
      @frames << frame
      offset = frame_offset + frame.size
    else
      break
    end
  end
end

#size ⇒ Object 



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# File 'lib/mp3file/id3v2/tag.rb', line 39

def size
  @header.tag_size + 10
end