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,
  "LYRICS" => :lyrics
}

Instance Method Summary collapse

Instance Method Details

#parse_vorbis_comment(comment_content) ⇒ Object 



31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
 
# File 'lib/wahwah/ogg/vorbis_comment.rb', line 31

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

  vendor_length = comment_content.read(4).unpack1("V")
  comment_content.seek(vendor_length, IO::SEEK_CUR) # Skip vendor_string

  comment_list_length = comment_content.read(4).unpack1("V")

  comment_list_length.times do
    comment_length = comment_content.read(4).unpack1("V")
    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