Module: WahWah::Ogg::VorbisComment

Included in:
FlacTag, FlacTag, OpusTag, VorbisTag
Defined in:
lib/wahwah/ogg/vorbis_comment.rb

Overview

Vorbis comment structure:

1) [vendor_length] = read an unsigned integer of 32 bits 2) [vendor_string] = read a UTF-8 vector as [vendor_length] octets 3) [user_comment_list_length] = read an unsigned integer of 32 bits 4) iterate [user_comment_list_length] times {

  5) [length] = read an unsigned integer of 32 bits
  6) this iteration’s user comment = read a UTF-8 vector as [length] octets
}

7) [framing_bit] = read a single bit as boolean 8) if ( [framing_bit] unset or end-of-packet ) then ERROR 9) done.

Constant Summary collapse

COMMET_FIELD_MAPPING = 
{
  'TITLE' => :title,
  'ALBUM' => :album,
  'ALBUMARTIST' => :albumartist,
  'TRACKNUMBER' => :track,
  'ARTIST' => :artist,
  'DATE' => :year,
  'GENRE' => :genre,
  'DISCNUMBER' => :disc,
  'COMPOSER' => :composer
}

Instance Method Summary collapse

Instance Method Details

#parse_vorbis_comment(comment_content) ⇒ Object 



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# File 'lib/wahwah/ogg/vorbis_comment.rb', line 30

def parse_vorbis_comment(comment_content)
  comment_content = StringIO.new(comment_content)

  vendor_length = comment_content.read(4).unpack('V').first
  comment_content.seek(vendor_length, IO::SEEK_CUR) # Skip vendor_string

  comment_list_length = comment_content.read(4).unpack('V').first

  comment_list_length.times do
    comment_length = comment_content.read(4).unpack('V').first
    comment = Helper.encode_to_utf8(comment_content.read(comment_length))
    field_name, field_value = comment.split('=', 2)
    attr_name = COMMET_FIELD_MAPPING[field_name&.upcase]

    field_value = field_value.to_i if %i(track disc).include? attr_name

    instance_variable_set("@#{attr_name}", field_value) unless attr_name.nil?
  end
end