</h3>
<dl>
<dt><i>datasource</i></dt>
<dd>Pointer to a data structure allocated by the calling application, containing any state needed by the callbacks provided.</dd>
<dt><i>vf</i></dt>
<dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile
functions. Once this has been called, the same <tt>OggVorbis_File</tt>
struct should be passed to all the libvorbisfile functions.</dd>
<dt><i>initial</i></dt>
<dd>Typically set to NULL.  This parameter is useful if some