bytes of the bos page contain
   magic data that uniquely identifies the required codec.  It is the
   responsibility of anyone fielding a new codec to make sure it is
   possible to reliably distinguish his/her codec from all other codecs
   in use.  There is no fixed way to detect the end of the codec-
   identifying marker.  The format of the bos page is dependent on the
   codec and therefore MUST be given in the encapsulation specification
   of that logical bitstream type.  Ogg also allows but does not require
   secondary header packets after the bos page for logical bitstreams
   and these must also precede any data packets in any logical
   bitstream.  These subsequent header packets are framed into an
   integral number of pages, which will not contain any data packets.
   So, a physical bitstream begins with the bos pages of all logical
   bitstreams containing one initial header packet per page, followed by
   the subsidiary header packets of all streams, followed by pages
   containing data packets.

   The encapsulation specification for one or more logical bitstreams is
   called a "media mapping".  An example for a media mapping is "Ogg
   Vorbis", which uses the Ogg framework to encapsulate Vorbis-encoded
   audio data for stream-based storage (such as files) and transport
   (such as TCP streams or pipes).  Ogg Vorbis provides the name and
   revision of the Vorbis codec, the audio rate and the audio quality on
   the Ogg Vorbis bos page.  It also uses two additional header pages
   per logical bitstream.  The Ogg Vorbis bos page starts with the byte
   0x01, followed by "vorbis" (a total of 7 bytes of identifier).




Pfeiffer                     Informational                      [Page 4]
