Merged revisions 296992 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.8

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  r296992 | tilghman | 2010-12-01 11:01:56 -0600 (Wed, 01 Dec 2010) | 19 lines
  
  Merged revisions 296991 via svnmerge from 
  https://origsvn.digium.com/svn/asterisk/branches/1.6.2
  
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    r296991 | tilghman | 2010-12-01 11:01:00 -0600 (Wed, 01 Dec 2010) | 12 lines
    
    Merged revisions 296990 via svnmerge from 
    https://origsvn.digium.com/svn/asterisk/branches/1.4
    
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      r296990 | tilghman | 2010-12-01 10:59:26 -0600 (Wed, 01 Dec 2010) | 5 lines
      
      Clarify documentation on how we store codec preference lists.
      
      (closes issue #18397)
       Reported by: birgita
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@296993 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/frame.h

@@ -714,7 +714,15 @@ int ast_parse_allow_disallow(struct ast_codec_pref *pref, format_t *mask, const
 /*! \brief Dump audio codec preference list into a string */
 int ast_codec_pref_string(struct ast_codec_pref *pref, char *buf, size_t size);
 
-/*! \brief Shift an audio codec preference list up or down 65 bytes so that it becomes an ASCII string */
+/*! \brief Shift an audio codec preference list up or down 65 bytes so that it becomes an ASCII string
+ * \note Due to a misunderstanding in how codec preferences are stored, this
+ * list starts at 'B', not 'A'.  For backwards compatibility reasons, this
+ * cannot change.
+ * \param pref A codec preference list structure
+ * \param buf A string denoting codec preference, appropriate for use in line transmission
+ * \param size Size of \a buf
+ * \param right Boolean:  if 0, convert from \a buf to \a pref; if 1, convert from \a pref to \a buf.
+ */
 void ast_codec_pref_convert(struct ast_codec_pref *pref, char *buf, size_t size, int right);
 
 /*! \brief Returns the number of samples contained in the frame */