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GStreamer 0.10 Core Reference Manual | ![]() |
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GstPadTemplateGstPadTemplate — Describe the media type of a pad. |
#include <gst/gst.h> GstPadTemplate; GstStaticPadTemplate; #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; enum GstPadPresence; GstPadTemplate* gst_pad_template_new (const gchar *name_template, GstPadDirection direction, GstPadPresence presence, GstCaps *caps); GstPadTemplate* gst_static_pad_template_get (GstStaticPadTemplate *pad_template); GstCaps* gst_static_pad_template_get_caps (GstStaticPadTemplate *templ); GstCaps* gst_pad_template_get_caps (GstPadTemplate *templ);
"pad-created" void user_function (GstPadTemplate *pad_template, GstPad *pad, gpointer user_data);
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 12. 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; }
typedef struct { gchar *name_template; GstPadDirection direction; GstPadPresence presence; GstStaticCaps static_caps; } GstStaticPadTemplate;
Structure describing the GstStaticPadTemplate.
gchar *name_template ; |
the name of the template |
GstPadDirection direction ; |
the direction of the template |
GstPadPresence presence ; |
the presence of the template |
GstStaticCaps static_caps ; |
the caps of the template. |
#define GST_PAD_TEMPLATE_NAME_TEMPLATE(templ) (((GstPadTemplate *)(templ))->name_template)
Get the nametemplate of the padtemplate.
templ : |
the template to query |
#define GST_PAD_TEMPLATE_DIRECTION(templ) (((GstPadTemplate *)(templ))->direction)
Get the direction of the padtemplate.
templ : |
the template to query |
#define GST_PAD_TEMPLATE_PRESENCE(templ) (((GstPadTemplate *)(templ))->presence)
Get the presence of the padtemplate.
templ : |
the template to query |
#define GST_PAD_TEMPLATE_CAPS(templ) (((GstPadTemplate *)(templ))->caps)
Get a handle to the padtemplate GstCaps
templ : |
the template to query |
#define GST_PAD_TEMPLATE_IS_FIXED(templ) (GST_OBJECT_FLAG_IS_SET(templ, GST_PAD_TEMPLATE_FIXED))
Check if the properties of the padtemplate are fixed
templ : |
the template to query |
typedef enum { GST_PAD_TEMPLATE_FIXED = (GST_OBJECT_FLAG_LAST << 0), /* padding */ GST_PAD_TEMPLATE_FLAG_LAST = (GST_OBJECT_FLAG_LAST << 4) } GstPadTemplateFlags;
Flags for the padtemplate
GST_PAD_TEMPLATE_FIXED |
the padtemplate has no variable properties |
GST_PAD_TEMPLATE_FLAG_LAST |
first flag that can be used by subclasses. |
typedef enum { GST_PAD_ALWAYS, GST_PAD_SOMETIMES, GST_PAD_REQUEST } GstPadPresence;
Indicates when this pad will become available.
GST_PAD_ALWAYS |
the pad is always available |
GST_PAD_SOMETIMES |
the pad will become available depending on the media stream |
GST_PAD_REQUEST |
the pad is only available on request with
gst_element_request_pad_by_name() or gst_element_request_compatible_pad() .
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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. |
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. |
GstCaps* gst_static_pad_template_get_caps (GstStaticPadTemplate *templ);
Gets the capabilities of the static pad template.
templ : |
a GstStaticPadTemplate to get capabilities of. |
Returns : | the GstCaps of the static pad template. If you need to keep a
reference to the caps, take a ref (see gst_caps_ref() ).
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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, take a ref (see gst_caps_ref() ).
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void user_function (GstPadTemplate *pad_template, GstPad *pad, gpointer user_data);
This signal is fired when an element creates a pad from this template.
pad_template : |
the object which received the signal. |
pad : |
the pad that was created. |
user_data : |
user data set when the signal handler was connected. |
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