Class: Ogg::Codecs::Vorbis

Inherits:
Object
  • Object
show all
Extended by:
VorbisComments
Defined in:
lib/ogg/codecs/vorbis.rb

Class Method Summary collapse

Methods included from VorbisComments

binary_size, pack_comments, unpack_comments

Class Method Details

.decode_headers(reader) ⇒ Object

consume header and tag pages, return array of two hashes, info and tags



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# File 'lib/ogg/codecs/vorbis.rb', line 11

def decode_headers(reader)
  init_pkt, tag_pkt, _ = reader.read_packets(3) # init_pkt, tag_pkt, setup_pkt
  info = extract_info(init_pkt)
  info[:tag], info[:tag_vendor] = unpack_comments(tag_pkt, "\003vorbis")
  info
end

.extract_info(packet) ⇒ Object 



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# 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

.match?(header_packet) ⇒ Boolean

return true/false based on whether the header packet belongs to us

Returns:

  • (Boolean) 


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# File 'lib/ogg/codecs/vorbis.rb', line 6

def match?(header_packet)
  header_packet.start_with?("\001vorbis")
end

.replace_tags(reader, writer, new_tags, vendor) ⇒ Object

consume pages with old tags/setup packets and rewrite newtags,setup packets return the number of pages written



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# File 'lib/ogg/codecs/vorbis.rb', line 20

def replace_tags(reader, writer, new_tags, vendor)
  _, setup_pkt = reader.read_packets(2) # tag_pkt, setup_pkt
  writer.write_packets(0, pack_comments(new_tags, vendor, "\003vorbis"), setup_pkt)
end