Sophie: libgstreamer0.7-devel-0.7.4-2mdk i586

libgstreamer0.7-devel-0.7.4-2mdk.i586.rpm

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><H1
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><A
NAME="section-factories-gstreamer-types"
>20.3. GStreamer types</A
></H1
><P
> 
      GStreamer assigns a unique number to all registered MIME types.
      GStreamer also keeps a reference to
      a function that can be used to determine if a given buffer is of
      the given MIME type.
    </P
><P
>&#13;      There is also an association between a MIME type and a file extension,
      but the use of typefind functions (similar to file(1)) is preferred.
    </P
><P
> 
      The type information is maintained in a list of 
      <CODE
CLASS="classname"
>GstType</CODE
>. The definition of a 
      <CODE
CLASS="classname"
>GstType</CODE
> is like:
    </P
><P
>&#13;      <PRE
CLASS="programlisting"
>&#13;typedef GstCaps (*GstTypeFindFunc) (GstBuffer *buf,gpointer *priv);
 
typedef struct _GstType GstType;

struct _GstType {
  guint16 id;                   /* type id (assigned) */

  gchar *mime;                  /* MIME type */
  gchar *exts;                  /* space-delimited list of extensions */

  GstTypeFindFunc typefindfunc; /* typefind function */
};
      </PRE
>
    </P
><P
> 
      All operations on <CODE
CLASS="classname"
>GstType</CODE
> occur
      via their <CODE
CLASS="classname"
>guint16 id</CODE
> numbers, with
      the <CODE
CLASS="classname"
>GstType</CODE
> structure private to the GStreamer
      library.
    </P
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN778"
>20.3.1. MIME type to id conversion</A
></H2
><P
> 
        We can obtain the id for a given MIME type
        with the following piece of code:
      </P
><PRE
CLASS="programlisting"
>&#13;  guint16 id;
  
  id = gst_type_find_by_mime ("audio/mpeg");
      </PRE
><P
> 
        This function will return 0 if the type was not known.
      </P
></DIV
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CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN783"
>20.3.2. id to <CODE
CLASS="classname"
>GstType</CODE
> conversion</A
></H2
><P
> 
        We can obtain the <CODE
CLASS="classname"
>GstType</CODE
> for a given id 
        with the following piece of code:
      </P
><PRE
CLASS="programlisting"
>&#13;  GstType *type;
  
  type = gst_type_find_by_id (id);
      </PRE
><P
> 
        This function will return NULL if the id was not associated with
        any known <CODE
CLASS="classname"
>GstType</CODE
>
      </P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN791"
>20.3.3. extension to id conversion</A
></H2
><P
> 
        We can obtain the id for a given file extension
        with the following piece of code:
      </P
><PRE
CLASS="programlisting"
>&#13;  guint16 id;
  
  id = gst_type_find_by_ext (".mp3");
      </PRE
><P
> 
        This function will return 0 if the extension was not known.
      </P
><P
>&#13;        For more information, see <A
HREF="chapter-autoplug.html"
>Chapter 28</A
>.
      </P
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