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GStreamer 0.10 Core Reference Manual | ![]() |
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GstPluginGstPlugin — Container for features loaded from a shared object module |
#include <gst/gst.h> GQuark gst_plugin_error_quark (void); #define GST_PLUGIN_ERROR enum GstPluginError; GstPlugin; GstPluginDesc; gboolean (*GstPluginInitFunc) (GstPlugin *plugin); #define GST_PLUGIN_DEFINE (major,minor,name,description,init,version,license,package,origin) #define GST_PLUGIN_DEFINE_STATIC (major,minor,name,description,init,version,license,package,origin) #define GST_LICENSE_UNKNOWN gboolean (*GstPluginFilter) (GstPlugin *plugin, gpointer user_data); const gchar* gst_plugin_get_name (GstPlugin *plugin); const gchar* gst_plugin_get_description (GstPlugin *plugin); const gchar* gst_plugin_get_filename (GstPlugin *plugin); const gchar* gst_plugin_get_license (GstPlugin *plugin); const gchar* gst_plugin_get_package (GstPlugin *plugin); const gchar* gst_plugin_get_origin (GstPlugin *plugin); const gchar* gst_plugin_get_source (GstPlugin *plugin); const gchar* gst_plugin_get_version (GstPlugin *plugin); GModule* gst_plugin_get_module (GstPlugin *plugin); gboolean gst_plugin_is_loaded (GstPlugin *plugin); gboolean gst_plugin_name_filter (GstPlugin *plugin, const gchar *name); GstPlugin* gst_plugin_load_file (const gchar *filename, GError **error); GstPlugin* gst_plugin_load (GstPlugin *plugin); GstPlugin* gst_plugin_load_by_name (const gchar *name); void gst_plugin_list_free (GList *list);
GStreamer is extensible, so GstElement instances can be loaded at runtime. A plugin system can provide one or more of the basic GStreamer GstPluginFeature subclasses.
A plugin should export a symbol plugin_desc that is a struct of type GstPluginDesc. the plugin loader will check the version of the core library the plugin was linked against and will create a new GstPlugin. It will then call the GstPluginInitFunc function that was provided in the plugin_desc.
Once you have a handle to a GstPlugin (e.g. from the GstRegistryPool), you can add any object that subclasses GstPluginFeature.
Use gst_plugin_find_feature()
and gst_plugin_get_feature_list()
to find
features in a plugin.
Usually plugins are always automaticlly loaded so you don't need to call
gst_plugin_load()
explicitly to bring it into memory. There are options to
statically link plugins to an app or even use GStreamer without a plugin
repository in which case gst_plugin_load()
can be needed to bring the plugin
into memory.
GQuark gst_plugin_error_quark (void);
Get the error quark.
Returns : | The error quark used in GError messages |
#define GST_PLUGIN_ERROR gst_plugin_error_quark ()
The error message category quark
typedef enum { GST_PLUGIN_ERROR_MODULE, GST_PLUGIN_ERROR_DEPENDENCIES, GST_PLUGIN_ERROR_NAME_MISMATCH } GstPluginError;
The plugin loading errors
GST_PLUGIN_ERROR_MODULE |
The plugin could not be loaded |
GST_PLUGIN_ERROR_DEPENDENCIES |
The plugin has unresolved dependencies |
GST_PLUGIN_ERROR_NAME_MISMATCH |
The plugin has already be loaded from a different file |
typedef struct { gint major_version; gint minor_version; gchar *name; gchar *description; GstPluginInitFunc plugin_init; gchar *version; gchar *license; gchar *source; gchar *package; gchar *origin; gpointer _gst_reserved[GST_PADDING]; } GstPluginDesc;
A plugins should export a variable of this type called plugin_desc. This plugin loaded will use this variable to initialize the plugin.
gint major_version ; |
the major version number of core that plugin was compiled for |
gint minor_version ; |
the minor version number of core that plugin was compiled for |
gchar *name ; |
a unique name of the plugin |
gchar *description ; |
description of plugin |
GstPluginInitFunc plugin_init ; |
pointer to the init function of this plugin. |
gchar *version ; |
version of the plugin |
gchar *license ; |
effective license of plugin |
gchar *source ; |
source module plugin belongs to |
gchar *package ; |
shipped package plugin belongs to |
gchar *origin ; |
URL to provider of plugin |
gpointer _gst_reserved [GST_PADDING]; |
private, for later expansion |
gboolean (*GstPluginInitFunc) (GstPlugin *plugin);
A plugin should provide a pointer to a function of this type in the plugin_desc struct. This function will be called by the loader at startup.
plugin : |
The plugin object that can be used to register GstPluginFeatures for this plugin. |
Returns : | TRUE if plugin initialised successfully
|
#define GST_PLUGIN_DEFINE(major,minor,name,description,init,version,license,package,origin)
This macro needs to be used to define the entry point and meta data of a plugin. One would use this macro to export a plugin, so that it can be used by other applications
major : |
major version number of the gstreamer-core that plugin was compiled for |
minor : |
minor version number of the gstreamer-core that plugin was compiled for |
name : |
short, but unique name of the plugin |
description : |
information about the purpose of the plugin |
init : |
function pointer to the plugin_init method with the signature of static gboolean plugin_init (GstPlugin * plugin) .
|
version : |
full version string (e.g. VERSION from config.h) |
license : |
under which licence the package has been released, e.g. GPL, LGPL. |
package : |
the package-name (e.g. PACKAGE_NAME from config.h) |
origin : |
a description from where the package comes from (e.g. the homepage URL) |
#define GST_PLUGIN_DEFINE_STATIC(major,minor,name,description,init,version,license,package,origin)
This macro needs to be used to define the entry point and meta data of a local plugin. One would use this macro to define a local plugin that can only be used by the own application.
major : |
major version number of the gstreamer-core that plugin was compiled for |
minor : |
minor version number of the gstreamer-core that plugin was compiled for |
name : |
short, but unique name of the plugin |
description : |
information about the purpose of the plugin |
init : |
function pointer to the plugin_init method with the signature of static gboolean plugin_init (GstPlugin * plugin) .
|
version : |
full version string (e.g. VERSION from config.h) |
license : |
under which licence the package has been released, e.g. GPL, LGPL. |
package : |
the package-name (e.g. PACKAGE_NAME from config.h) |
origin : |
a description from where the package comes from (e.g. the homepage URL) |
#define GST_LICENSE_UNKNOWN "unknown"
To be used in GST_PLUGIN_DEFINE or GST_PLUGIN_DEFINE_STATIC if usure about the licence.
gboolean (*GstPluginFilter) (GstPlugin *plugin, gpointer user_data);
A function that can be used with e.g. gst_registry_plugin_filter()
to get a list of plugins that match certain criteria.
plugin : |
the plugin to check |
user_data : |
the user_data that has been passed on e.g. gst_registry_plugin_filter()
|
Returns : | TRUE for a positive match, FALSE otherwise |
const gchar* gst_plugin_get_name (GstPlugin *plugin);
Get the short name of the plugin
plugin : |
plugin to get the name of |
Returns : | the name of the plugin |
const gchar* gst_plugin_get_description (GstPlugin *plugin);
Get the long descriptive name of the plugin
plugin : |
plugin to get long name of |
Returns : | the long name of the plugin |
const gchar* gst_plugin_get_filename (GstPlugin *plugin);
get the filename of the plugin
plugin : |
plugin to get the filename of |
Returns : | the filename of the plugin |
const gchar* gst_plugin_get_license (GstPlugin *plugin);
get the license of the plugin
plugin : |
plugin to get the license of |
Returns : | the license of the plugin |
const gchar* gst_plugin_get_package (GstPlugin *plugin);
get the package the plugin belongs to.
plugin : |
plugin to get the package of |
Returns : | the package of the plugin |
const gchar* gst_plugin_get_origin (GstPlugin *plugin);
get the URL where the plugin comes from
plugin : |
plugin to get the origin of |
Returns : | the origin of the plugin |
const gchar* gst_plugin_get_source (GstPlugin *plugin);
get the source module the plugin belongs to.
plugin : |
plugin to get the source of |
Returns : | the source of the plugin |
const gchar* gst_plugin_get_version (GstPlugin *plugin);
get the version of the plugin
plugin : |
plugin to get the version of |
Returns : | the version of the plugin |
GModule* gst_plugin_get_module (GstPlugin *plugin);
Gets the GModule of the plugin. If the plugin isn't loaded yet, NULL is returned.
plugin : |
plugin to query |
Returns : | module belonging to the plugin or NULL if the plugin isn't loaded yet. |
gboolean gst_plugin_is_loaded (GstPlugin *plugin);
queries if the plugin is loaded into memory
plugin : |
plugin to query |
Returns : | TRUE is loaded, FALSE otherwise |
gboolean gst_plugin_name_filter (GstPlugin *plugin, const gchar *name);
A standard filter that returns TRUE when the plugin is of the given name.
plugin : |
the plugin to check |
name : |
the name of the plugin |
Returns : | TRUE if the plugin is of the given name. |
GstPlugin* gst_plugin_load_file (const gchar *filename, GError **error);
Loads the given plugin and refs it. Caller needs to unref after use.
filename : |
the plugin filename to load |
error : |
pointer to a NULL-valued GError |
Returns : | a reference to the existing loaded GstPlugin, a reference to the newly-loaded GstPlugin, or NULL if an error occurred. |
GstPlugin* gst_plugin_load (GstPlugin *plugin);
Loads plugin
. Note that the *return value* is the loaded plugin; plugin
is
untouched. The normal use pattern of this function goes like this:
GstPlugin *loaded_plugin; loaded_plugin = gst_plugin_load (plugin); // presumably, we're no longer interested in the potentially-unloaded plugin gst_object_unref (plugin); plugin = loaded_plugin;
plugin : |
plugin to load |
Returns : | A reference to a loaded plugin, or NULL on error. |
GstPlugin* gst_plugin_load_by_name (const gchar *name);
Load the named plugin. Refs the plugin.
name : |
name of plugin to load |
Returns : | A reference to a loaded plugin, or NULL on error. |
void gst_plugin_list_free (GList *list);
Unrefs each member of list
, then frees the list.
list : |
list of GstPlugin |
<< GstPipeline | GstPluginFeature >> |