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83 lines
2.3 KiB
XML
83 lines
2.3 KiB
XML
<chapter id="cha-plugins">
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<title>Plugins</title>
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<!-- FIXME: introduce type definitions before this chapter -->
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<para>
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A plugin is a shared library that contains at least one of the following
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items:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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one or more element factories
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</para>
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</listitem>
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<listitem>
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<para>
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one or more type definitions
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</para>
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</listitem>
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<listitem>
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<para>
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one or more auto-pluggers
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</para>
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</listitem>
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<listitem>
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<para>
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exported symbols for use in other plugins
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</para>
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</listitem>
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</itemizedlist>
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<para>
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All plugins should implement one function, <function>plugin_init</function>,
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that creates all the element factories and registers all the type
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definitions contained in the plugin.
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Without this function, a plugin cannot be registered.
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</para>
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<para>
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The plugins are maintained in the plugin system. Optionally, the
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type definitions and the element factories can be saved into an XML
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representation so that the plugin system does not have to load all
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available plugins in order to know their definition.
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</para>
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<para>
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The basic plugin structure has the following fields:
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</para>
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<programlisting>
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typedef struct _GstPlugin GstPlugin;
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struct _GstPlugin {
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gchar *name; /* name of the plugin */
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gchar *longname; /* long name of plugin */
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gchar *filename; /* filename it came from */
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GList *types; /* list of types provided */
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gint numtypes;
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GList *elements; /* list of elements provided */
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gint numelements;
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GList *autopluggers; /* list of autopluggers provided */
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gint numautopluggers;
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gboolean loaded; /* if the plugin is in memory */
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};
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</programlisting>
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<para>
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You can query a <classname>GList</classname> of available plugins with the
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function <function>gst_plugin_get_list</function> as this example shows:
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</para>
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<programlisting>
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GList *plugins;
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plugins = gst_plugin_get_list ();
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while (plugins) {
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GstPlugin *plugin = (GstPlugin *)plugins->data;
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g_print ("plugin: %s\n", gst_plugin_get_name (plugin));
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plugins = g_list_next (plugins);
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}
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</programlisting>
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</chapter>
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