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GstPadTemplate

GstPadTemplate — Describe the media type of a pad.

Synopsis


#include <gst/gst.h>


struct      GstPadTemplate;
struct      GstStaticPadTemplate;
#define     GST_IS_GHOST_PAD_FAST           (obj)
#define     GST_IS_PAD_FAST                 (obj)
#define     GST_PAD_TEMPLATE_NAME_TEMPLATE  (templ)
#define     GST_PAD_TEMPLATE_DIRECTION      (templ)
#define     GST_PAD_TEMPLATE_PRESENCE       (templ)
#define     GST_PAD_TEMPLATE_CAPS           (templ)
#define     GST_PAD_TEMPLATE_IS_FIXED       (templ)
enum        GstPadTemplateFlags;
GstPadTemplate* gst_pad_template_new        (const gchar *name_template,
                                             GstPadDirection direction,
                                             GstPadPresence presence,
                                             GstCaps *caps);
GstPadTemplate* gst_static_pad_template_get (GstStaticPadTemplate *pad_template);
const GstCaps* gst_pad_template_get_caps    (GstPadTemplate *templ);
const GstCaps* gst_pad_template_get_caps_by_name
                                            (GstPadTemplate *templ,
                                             const gchar *name);

Object Hierarchy


  GObject
   +----GstObject
         +----GstPadTemplate

Signal Prototypes


"pad-created"
            void        user_function      (GstPadTemplate *gstpadtemplate,
                                            GstPad *arg1,
                                            gpointer user_data);

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_pad_template_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_pad_template_new() or with the convenient GST_PAD_TEMPLATE_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.

Example 6. Create a pad from a padtemplate

  GstStaticPadTemplate my_template =
  GST_STATIC_PAD_TEMPLATE (
    "sink",		/* the name of the pad */
    GST_PAD_SINK,	/* the direction of the pad */
    GST_PAD_ALWAYS, 	/* when this pad will be present */
    GST_STATIC_CAPS (	/* the capabilities of the padtemplate */
      "audio/x-raw-int, "
        "channels = (int) [ 1, 6 ]"
    )
  )

  void
  my_method (void) 
  {
    GstPad *pad;
  
    pad = gst_pad_new_from_template (GST_PAD_TEMPLATE_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_element_factory_new ("my_factory", GST_TYPE_MYFACTORY, &gst_myfactory_details);
    g_return_val_if_fail (factory != NULL, FALSE);

    gst_element_factory_add_pad_template (factory, GST_PAD_TEMPLATE_GET (my_template_factory));

    gst_plugin_add_feature (plugin, GST_PLUGIN_FEATURE (factory));

    return TRUE;
  }

Details

struct GstPadTemplate

struct GstPadTemplate;

The padtemplate object.

struct GstStaticPadTemplate

struct GstStaticPadTemplate {

  gchar           *name_template;
  GstPadDirection  direction;
  GstPadPresence   presence;
  GstStaticCaps   static_caps;
};

GST_IS_GHOST_PAD_FAST()

#define GST_IS_GHOST_PAD_FAST(obj)	(G_OBJECT_TYPE(obj) == GST_TYPE_GHOST_PAD)

obj :

GST_IS_PAD_FAST()

#define     GST_IS_PAD_FAST(obj)

obj :

GST_PAD_TEMPLATE_NAME_TEMPLATE()

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

Get the nametemplate of the padtemplate.

templ :the template to query

GST_PAD_TEMPLATE_DIRECTION()

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

Get the direction of the padtemplate.

templ :the template to query

GST_PAD_TEMPLATE_PRESENCE()

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

Get the presence of the padtemplate.

templ :the template to query

GST_PAD_TEMPLATE_CAPS()

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

Get a handle to the padtemplate GstCaps

templ :the template to query

GST_PAD_TEMPLATE_IS_FIXED()

#define GST_PAD_TEMPLATE_IS_FIXED(templ)	(GST_FLAG_IS_SET(templ, GST_PAD_TEMPLATE_FIXED))

Check if the properties of the padtemplate are fixed

templ :the template to query

enum GstPadTemplateFlags

typedef enum {
  GST_PAD_TEMPLATE_FIXED	= GST_OBJECT_FLAG_LAST,

  GST_PAD_TEMPLATE_FLAG_LAST	= GST_OBJECT_FLAG_LAST + 4
} GstPadTemplateFlags;

Flags for the padtemplate

GST_PAD_TEMPLATE_FIXEDthe padtemplate has no variable properties
GST_PAD_TEMPLATE_FLAG_LASTfirst flag that can be used by subclasses.

gst_pad_template_new ()

GstPadTemplate* gst_pad_template_new        (const gchar *name_template,
                                             GstPadDirection direction,
                                             GstPadPresence presence,
                                             GstCaps *caps);

Creates a new pad template with a name according to the given template and with the given arguments. This functions takes ownership of the provided caps, so be sure to not use them afterwards.

name_template : the name template.
direction : the GstPadDirection of the template.
presence : the GstPadPresence of the pad.
caps : a GstCaps set for the template. The caps are taken ownership of.
Returns : a new GstPadTemplate.

gst_static_pad_template_get ()

GstPadTemplate* gst_static_pad_template_get (GstStaticPadTemplate *pad_template);

Converts a GstStaticPadTemplate into a GstPadTemplate.

pad_template : the static pad template
Returns : a new GstPadTemplate.

gst_pad_template_get_caps ()

const GstCaps* gst_pad_template_get_caps    (GstPadTemplate *templ);

Gets the capabilities of the pad template.

templ : a GstPadTemplate to get capabilities of.
Returns : the GstCaps of the pad template. If you need to keep a reference to the caps, make a copy (see gst_caps_copy()).

gst_pad_template_get_caps_by_name ()

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

Warning

gst_pad_template_get_caps_by_name is deprecated and should not be used in newly-written code.

Gets the capability with the given name from templ.

templ : a GstPadTemplate to get the capabilities of.
name : the name of the capability to get.
Returns : the GstCaps of this pad template, or NULL if not found. If you intend to keep a reference on the caps, make a copy (see gst_caps_copy()).

Signals

The "pad-created" signal

void        user_function                  (GstPadTemplate *gstpadtemplate,
                                            GstPad *arg1,
                                            gpointer user_data);

This signal is fired when an element creates a pad from this template.

gstpadtemplate :the object which received the signal.
arg1 :The pad that was created.
user_data :user data set when the signal handler was connected.

See Also

GstPad, GstElementFactory

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