GstPadTemplate

Name

GstPadTemplate -- Describe the media type of a pad.

Synopsis


#include <gst/gst.h>


enum        GstPadPresence;
struct      GstPadTemplate;
#define     GST_PADTEMPLATE_CAPS            (templ)
#define     GST_PADTEMPLATE_DIRECTION       (templ)
#define     GST_PADTEMPLATE_NAME_TEMPLATE   (templ)
#define     GST_PADTEMPLATE_PRESENCE        (templ)
#define     GST_PADTEMPLATE_NEW             (padname, dir, pres, a...)
#define     GST_PADTEMPLATE_FACTORY         (name, padname, dir, pres, a...)
#define     GST_PADTEMPLATE_GET             (fact)
#define     GST_PADTEMPLATE_FIXED           (templ)
#define     GST_PADTEMPLATE_IS_FIXED        (templ)
GstPadTemplate* gst_padtemplate_new         (gchar *name_template,
                                             GstPadDirection direction,
                                             GstPadPresence presence,
                                             GstCaps *caps,
                                             ...);
GstPadTemplate* gst_padtemplate_load_thyself
                                            (xmlNodePtr parent);
xmlNodePtr  gst_padtemplate_save_thyself    (GstPadTemplate *templ,
                                             xmlNodePtr parent);
GstCaps*    gst_padtemplate_get_caps        (GstPadTemplate *templ);
GstCaps*    gst_padtemplate_get_caps_by_name
                                            (GstPadTemplate *templ,
                                             const gchar *name);

Description

Padtemplates describe the possible media types a pad or an elementfactory can handle.

Pad and PadTemplates have GstCaps attached to it to describe the media type they are capable of dealing with. gst_padtemplate_get_caps() is used to get the caps of a padtemplate. It's not possible to modify the caps of a padtemplate after creation.

Padtemplates can be created with gst_padtemplate_new() or with the convenient GST_PADTEMPLATE_FACTORY() macro. A padtemplate can be used to create a pad or to add to an elementfactory.

The following code example shows the code to create a pad from a padtemplate.
  GST_PADTEMPLATE_FACTORY (my_template_factory,
    "sink",		/* the name of the pad */
    GST_PAD_SINK,	/* the direction of the pad */
    GST_PAD_ALWAYS, 	/* when this pad will be present */
    GST_CAPS_NEW (	/* the capabilities of the padtemplate */
      "my_caps",
      "audio/raw",
        "format",	GST_PROPS_STRING ("int"),
        "channels",	GST_PROPS_INT_RANGE (1, 6)
    )
  )

  void
  my_method (void) 
  {
    GstPad *pad;
  
    pad = gst_pad_new_from_template (GST_PADTEMPLATE_GET (my_template_factory), "sink");
    ...
  }

The following example shows you how to add the padtemplate to an elementfactory:
  gboolean
  my_factory_init (GstPlugin *plugin)
  {
    GstElementFactory *factory;

    factory = gst_elementfactory_new ("my_factory", GST_TYPE_MYFACTORY, &gst_myfactory_details);
    g_return_val_if_fail (factory != NULL, FALSE);

    gst_elementfactory_add_padtemplate (factory, GST_PADTEMPLATE_GET (my_template_factory));

    gst_plugin_add_feature (plugin, GST_PLUGIN_FEATURE (factory));

    return TRUE;
  }

Details

enum GstPadPresence

typedef enum {
  GST_PAD_ALWAYS,
  GST_PAD_SOMETIMES,
  GST_PAD_REQUEST,
} GstPadPresence;

Indicates when this pad will become available.

GST_PAD_ALWAYSthe pad is always available
GST_PAD_SOMETIMESthe pad will become available depending on the media stream
GST_PAD_REQUESTth pad is only available on request with gst_element_request_pad_by_name() or gst_element_request_compatible_pad().


struct GstPadTemplate

struct GstPadTemplate {
  GstObject	  object;

  gchar           *name_template;
  GstPadDirection direction;
  GstPadPresence  presence;
  GstCaps	  *caps;
  gboolean	  fixed;
};


GST_PADTEMPLATE_CAPS()

#define GST_PADTEMPLATE_CAPS(templ)		(((GstPadTemplate *)(templ))->caps)

Get a handle to the padtemplate GstCaps

templ :the template to query


GST_PADTEMPLATE_DIRECTION()

#define GST_PADTEMPLATE_DIRECTION(templ)	(((GstPadTemplate *)(templ))->direction)

Get the direction of the padtemplate.

templ :the template to query


GST_PADTEMPLATE_NAME_TEMPLATE()

#define GST_PADTEMPLATE_NAME_TEMPLATE(templ)	(((GstPadTemplate *)(templ))->name_template)

Get the nametemplate of the padtemplate.

templ :the template to query


GST_PADTEMPLATE_PRESENCE()

#define GST_PADTEMPLATE_PRESENCE(templ)		(((GstPadTemplate *)(templ))->presence)

Get the presence of the padtemplate.

templ :the template to query


GST_PADTEMPLATE_NEW()

#define     GST_PADTEMPLATE_NEW(padname, dir, pres, a...)

Create a new padtemplate.

padname :the nametemplate for the pads that will be created with this template
dir :the direction of the pads.
pres :the presence of the pads.
a... :the capabilities of this padtemplate usually created with GST_CAPS_NEW()


GST_PADTEMPLATE_FACTORY()

#define     GST_PADTEMPLATE_FACTORY(name, padname, dir, pres, a...)

Create a factory for a padtemplate. This can be used if you only want one instance of the padtemplate. Use GST_PADTEMPLATE_GET() to get the unique padtemplate.

name :th name of the factory
padname :the nametemplate of the pads
dir :the direction of the pads.
pres :the presence of the pads.
a... :the capabilities of this padtemplate, usually created with GST_CAPS_NEW()


GST_PADTEMPLATE_GET()

#define GST_PADTEMPLATE_GET(fact) (fact)()

Get the padtemplate of the factory created with GST_PADTEMPLATE_FACTORY()

fact :the factory name to get the padtemplate from.


GST_PADTEMPLATE_FIXED()

#define GST_PADTEMPLATE_FIXED(templ)		(((GstPadTemplate *)(templ))->fixed)

templ : 


GST_PADTEMPLATE_IS_FIXED()

#define GST_PADTEMPLATE_IS_FIXED(templ)		(GST_PADTEMPLATE_FIXED(templ) == TRUE)

templ : 


gst_padtemplate_new ()

GstPadTemplate* gst_padtemplate_new         (gchar *name_template,
                                             GstPadDirection direction,
                                             GstPadPresence presence,
                                             GstCaps *caps,
                                             ...);

Creates a new padtemplate from the given arguments.

name_template : the name template
direction : the direction for the template
presence : the presence of the pad
caps : a list of capabilities for the template
... : more capabilities
Returns : the new padtemplate


gst_padtemplate_load_thyself ()

GstPadTemplate* gst_padtemplate_load_thyself
                                            (xmlNodePtr parent);

Loads a padtemplate from the XML tree.

parent : the source XML tree
Returns : the new padtemplate


gst_padtemplate_save_thyself ()

xmlNodePtr  gst_padtemplate_save_thyself    (GstPadTemplate *templ,
                                             xmlNodePtr parent);

Saves the padtemplate into XML.

templ : the padtemplate to save
parent : the parent XML tree
Returns : the new XML tree


gst_padtemplate_get_caps ()

GstCaps*    gst_padtemplate_get_caps        (GstPadTemplate *templ);

Get the capabilities of the padtemplate

templ : the padtemplate to use
Returns : a GstCaps*


gst_padtemplate_get_caps_by_name ()

GstCaps*    gst_padtemplate_get_caps_by_name
                                            (GstPadTemplate *templ,
                                             const gchar *name);

Get the capability with the given name from this padtemplate.

templ : the padtemplate to get the capabilities from
name : the name of the capability to get
Returns : a capability or NULL if not found

See Also

GstPad, GstElementFactory