# File lib/ogg/codecs/vorbis.rb, line 25
      def extract_info(packet)
        vorbis_string,
        vorbis_version,
        channels,
        samplerate,
        upper_bitrate,
        nominal_bitrate,
        lower_bitrate = packet.unpack("a7VCV4")
        
        if nominal_bitrate == 0
          if (upper_bitrate == 2**32 - 1) || (lower_bitrate == 2**32 - 1)
            nominal_bitrate = 0
          else
            nominal_bitrate = ( upper_bitrate + lower_bitrate) / 2
          end
        end
        
        return { :channels => channels, :samplerate => samplerate, :nominal_bitrate => nominal_bitrate }
      end