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454 lines
14 KiB
C
454 lines
14 KiB
C
/* GStreamer
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* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
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* 2000 Wim Taymans <wtay@chello.be>
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*
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* gstpadtemplate.c: Templates for pad creation
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/**
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* SECTION:gstpadtemplate
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* @short_description: Describe the media type of a pad.
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* @see_also: #GstPad, #GstElementFactory
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*
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* Padtemplates describe the possible media types a pad or an elementfactory can
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* handle. This allows for both inspection of handled types before loading the
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* element plugin as well as identifying pads on elements that are not yet
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* created (request or sometimes pads).
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*
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* Pad and PadTemplates have #GstCaps attached to it to describe the media type
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* they are capable of dealing with. gst_pad_template_get_caps() or
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* GST_PAD_TEMPLATE_CAPS() are used to get the caps of a padtemplate. It's not
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* possible to modify the caps of a padtemplate after creation.
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*
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* PadTemplates have a #GstPadPresence property which identifies the lifetime
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* of the pad and that can be retrieved with GST_PAD_TEMPLATE_PRESENCE(). Also
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* the direction of the pad can be retrieved from the #GstPadTemplate with
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* GST_PAD_TEMPLATE_DIRECTION().
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*
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* The GST_PAD_TEMPLATE_NAME_TEMPLATE () is important for GST_PAD_REQUEST pads
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* because it has to be used as the name in the gst_element_get_request_pad()
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* call to instantiate a pad from this template.
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*
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* Padtemplates can be created with gst_pad_template_new() or with
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* gst_static_pad_template_get (), which creates a #GstPadTemplate from a
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* #GstStaticPadTemplate that can be filled with the
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* convenient GST_STATIC_PAD_TEMPLATE() macro.
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*
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* A padtemplate can be used to create a pad (see gst_pad_new_from_template()
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* or gst_pad_new_from_static_template ()) or to add to an element class
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* (see gst_element_class_add_pad_template ()).
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*
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* The following code example shows the code to create a pad from a padtemplate.
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* <example>
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* <title>Create a pad from a padtemplate</title>
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* <programlisting>
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* GstStaticPadTemplate my_template =
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* GST_STATIC_PAD_TEMPLATE (
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* "sink", // the name of the pad
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* GST_PAD_SINK, // the direction of the pad
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* GST_PAD_ALWAYS, // when this pad will be present
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* GST_STATIC_CAPS ( // the capabilities of the padtemplate
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* "audio/x-raw-int, "
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* "channels = (int) [ 1, 6 ]"
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* )
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* );
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* void
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* my_method (void)
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* {
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* GstPad *pad;
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* pad = gst_pad_new_from_static_template (&my_template, "sink");
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* ...
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* }
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* </programlisting>
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* </example>
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*
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* The following example shows you how to add the padtemplate to an
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* element class, this is usually done in the class_init of the class:
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* <informalexample>
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* <programlisting>
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* static void
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* my_element_class_init (GstMyElementClass *klass)
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* {
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* GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);
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*
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* gst_element_class_add_pad_template (gstelement_class,
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* gst_static_pad_template_get (&my_template));
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* }
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* </programlisting>
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* </informalexample>
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*
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* Last reviewed on 2006-02-14 (0.10.3)
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*/
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#include "gst_private.h"
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#include "gstpad.h"
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#include "gstpadtemplate.h"
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#include "gstenumtypes.h"
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#include "gstmarshal.h"
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#include "gstutils.h"
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#include "gstinfo.h"
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#include "gsterror.h"
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#include "gstvalue.h"
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#define GST_CAT_DEFAULT GST_CAT_PADS
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enum
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{
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PROP_NAME_TEMPLATE = 1,
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PROP_DIRECTION,
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PROP_PRESENCE,
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PROP_CAPS
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};
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enum
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{
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TEMPL_PAD_CREATED,
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/* FILL ME */
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LAST_SIGNAL
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};
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static guint gst_pad_template_signals[LAST_SIGNAL] = { 0 };
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static void gst_pad_template_dispose (GObject * object);
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static void gst_pad_template_set_property (GObject * object, guint prop_id,
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const GValue * value, GParamSpec * pspec);
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static void gst_pad_template_get_property (GObject * object, guint prop_id,
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GValue * value, GParamSpec * pspec);
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#define gst_pad_template_parent_class parent_class
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G_DEFINE_TYPE (GstPadTemplate, gst_pad_template, GST_TYPE_OBJECT);
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static void
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gst_pad_template_class_init (GstPadTemplateClass * klass)
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{
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GObjectClass *gobject_class;
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GstObjectClass *gstobject_class;
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gobject_class = (GObjectClass *) klass;
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gstobject_class = (GstObjectClass *) klass;
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/**
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* GstPadTemplate::pad-created:
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* @pad_template: the object which received the signal.
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* @pad: the pad that was created.
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*
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* This signal is fired when an element creates a pad from this template.
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*/
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gst_pad_template_signals[TEMPL_PAD_CREATED] =
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g_signal_new ("pad-created", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
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G_STRUCT_OFFSET (GstPadTemplateClass, pad_created),
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NULL, NULL, gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
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gobject_class->dispose = gst_pad_template_dispose;
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gobject_class->get_property = gst_pad_template_get_property;
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gobject_class->set_property = gst_pad_template_set_property;
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/**
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* GstPadTemplate:name-template
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*
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* The name template of the pad template.
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*
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* Since: 0.10.21
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*/
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g_object_class_install_property (gobject_class, PROP_NAME_TEMPLATE,
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g_param_spec_string ("name-template", "Name template",
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"The name template of the pad template", NULL,
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G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
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/**
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* GstPadTemplate:direction
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*
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* The direction of the pad described by the pad template.
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*
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* Since: 0.10.21
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*/
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g_object_class_install_property (gobject_class, PROP_DIRECTION,
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g_param_spec_enum ("direction", "Direction",
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"The direction of the pad described by the pad template",
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GST_TYPE_PAD_DIRECTION, GST_PAD_UNKNOWN,
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G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
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/**
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* GstPadTemplate:presence
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*
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* When the pad described by the pad template will become available.
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*
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* Since: 0.10.21
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*/
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g_object_class_install_property (gobject_class, PROP_PRESENCE,
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g_param_spec_enum ("presence", "Presence",
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"When the pad described by the pad template will become available",
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GST_TYPE_PAD_PRESENCE, GST_PAD_ALWAYS,
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G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
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/**
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* GstPadTemplate:caps
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*
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* The capabilities of the pad described by the pad template.
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*
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* Since: 0.10.21
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*/
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g_object_class_install_property (gobject_class, PROP_CAPS,
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g_param_spec_boxed ("caps", "Caps",
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"The capabilities of the pad described by the pad template",
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GST_TYPE_CAPS,
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G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
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gstobject_class->path_string_separator = "*";
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}
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static void
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gst_pad_template_init (GstPadTemplate * templ)
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{
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}
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static void
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gst_pad_template_dispose (GObject * object)
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{
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GstPadTemplate *templ = GST_PAD_TEMPLATE (object);
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g_free (GST_PAD_TEMPLATE_NAME_TEMPLATE (templ));
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if (GST_PAD_TEMPLATE_CAPS (templ)) {
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gst_caps_unref (GST_PAD_TEMPLATE_CAPS (templ));
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}
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G_OBJECT_CLASS (parent_class)->dispose (object);
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}
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/* ALWAYS padtemplates cannot have conversion specifications (like src_%d),
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* since it doesn't make sense.
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* SOMETIMES padtemplates can do whatever they want, they are provided by the
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* element.
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* REQUEST padtemplates can be reverse-parsed (the user asks for 'sink1', the
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* 'sink%d' template is automatically selected), so we need to restrict their
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* naming.
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*/
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static gboolean
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name_is_valid (const gchar * name, GstPadPresence presence)
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{
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const gchar *str;
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if (presence == GST_PAD_ALWAYS) {
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if (strchr (name, '%')) {
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g_warning ("invalid name template %s: conversion specifications are not"
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" allowed for GST_PAD_ALWAYS padtemplates", name);
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return FALSE;
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}
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} else if (presence == GST_PAD_REQUEST) {
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if ((str = strchr (name, '%')) && strchr (str + 1, '%')) {
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g_warning ("invalid name template %s: only one conversion specification"
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" allowed in GST_PAD_REQUEST padtemplate", name);
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return FALSE;
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}
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if (str && (*(str + 1) != 's' && *(str + 1) != 'd' && *(str + 1) != 'u')) {
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g_warning ("invalid name template %s: conversion specification must be of"
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" type '%%d', '%%u' or '%%s' for GST_PAD_REQUEST padtemplate", name);
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return FALSE;
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}
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if (str && (*(str + 2) != '\0')) {
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g_warning ("invalid name template %s: conversion specification must"
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" appear at the end of the GST_PAD_REQUEST padtemplate name", name);
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return FALSE;
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}
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}
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return TRUE;
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}
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GType
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gst_static_pad_template_get_type (void)
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{
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static GType staticpadtemplate_type = 0;
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if (G_UNLIKELY (staticpadtemplate_type == 0)) {
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staticpadtemplate_type =
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g_pointer_type_register_static ("GstStaticPadTemplate");
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}
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return staticpadtemplate_type;
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}
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/**
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* gst_static_pad_template_get:
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* @pad_template: the static pad template
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*
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* Converts a #GstStaticPadTemplate into a #GstPadTemplate.
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*
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* Returns: (transfer full): a new #GstPadTemplate.
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*/
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/* FIXME0.11: rename to gst_pad_template_new_from_static_pad_template() */
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GstPadTemplate *
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gst_static_pad_template_get (GstStaticPadTemplate * pad_template)
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{
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GstPadTemplate *new;
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GstCaps *caps;
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if (!name_is_valid (pad_template->name_template, pad_template->presence))
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return NULL;
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caps = gst_static_caps_get (&pad_template->static_caps);
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new = g_object_new (gst_pad_template_get_type (),
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"name", pad_template->name_template,
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"name-template", pad_template->name_template,
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"direction", pad_template->direction,
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"presence", pad_template->presence, "caps", caps, NULL);
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gst_caps_unref (caps);
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return new;
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}
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/**
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* gst_pad_template_new:
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* @name_template: the name template.
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* @direction: the #GstPadDirection of the template.
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* @presence: the #GstPadPresence of the pad.
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* @caps: (transfer none): a #GstCaps set for the template.
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*
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* Creates a new pad template with a name according to the given template
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* and with the given arguments.
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*
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* Returns: (transfer full): a new #GstPadTemplate.
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*/
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GstPadTemplate *
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gst_pad_template_new (const gchar * name_template,
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GstPadDirection direction, GstPadPresence presence, GstCaps * caps)
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{
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GstPadTemplate *new;
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g_return_val_if_fail (name_template != NULL, NULL);
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g_return_val_if_fail (caps != NULL, NULL);
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g_return_val_if_fail (direction == GST_PAD_SRC
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|| direction == GST_PAD_SINK, NULL);
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g_return_val_if_fail (presence == GST_PAD_ALWAYS
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|| presence == GST_PAD_SOMETIMES || presence == GST_PAD_REQUEST, NULL);
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if (!name_is_valid (name_template, presence)) {
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return NULL;
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}
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new = g_object_new (gst_pad_template_get_type (),
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"name", name_template, "name-template", name_template,
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"direction", direction, "presence", presence, "caps", caps, NULL);
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return new;
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}
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/**
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* gst_static_pad_template_get_caps:
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* @templ: a #GstStaticPadTemplate to get capabilities of.
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*
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* Gets the capabilities of the static pad template.
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*
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* Returns: (transfer full): the #GstCaps of the static pad template.
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* Unref after usage. Since the core holds an additional
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* ref to the returned caps, use gst_caps_make_writable()
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* on the returned caps to modify it.
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*/
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GstCaps *
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gst_static_pad_template_get_caps (GstStaticPadTemplate * templ)
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{
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g_return_val_if_fail (templ, NULL);
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return (GstCaps *) gst_static_caps_get (&templ->static_caps);
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}
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/**
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* gst_pad_template_get_caps:
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* @templ: a #GstPadTemplate to get capabilities of.
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*
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* Gets the capabilities of the pad template.
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*
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* Returns: (transfer full): the #GstCaps of the pad template.
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* Unref after usage.
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*/
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GstCaps *
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gst_pad_template_get_caps (GstPadTemplate * templ)
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{
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GstCaps *caps;
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g_return_val_if_fail (GST_IS_PAD_TEMPLATE (templ), NULL);
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caps = GST_PAD_TEMPLATE_CAPS (templ);
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return (caps ? gst_caps_ref (caps) : NULL);
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}
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/**
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* gst_pad_template_pad_created:
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* @templ: a #GstPadTemplate that has been created
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* @pad: the #GstPad that created it
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*
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* Emit the pad-created signal for this template when created by this pad.
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*/
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void
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gst_pad_template_pad_created (GstPadTemplate * templ, GstPad * pad)
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{
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g_signal_emit (templ, gst_pad_template_signals[TEMPL_PAD_CREATED], 0, pad);
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}
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static void
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gst_pad_template_set_property (GObject * object, guint prop_id,
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const GValue * value, GParamSpec * pspec)
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{
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/* these properties are all construct-only */
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switch (prop_id) {
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case PROP_NAME_TEMPLATE:
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GST_PAD_TEMPLATE_NAME_TEMPLATE (object) = g_value_dup_string (value);
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break;
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case PROP_DIRECTION:
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GST_PAD_TEMPLATE_DIRECTION (object) =
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(GstPadDirection) g_value_get_enum (value);
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break;
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case PROP_PRESENCE:
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GST_PAD_TEMPLATE_PRESENCE (object) =
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(GstPadPresence) g_value_get_enum (value);
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break;
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case PROP_CAPS:
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GST_PAD_TEMPLATE_CAPS (object) = g_value_dup_boxed (value);
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break;
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default:
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G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
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break;
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}
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}
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static void
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gst_pad_template_get_property (GObject * object, guint prop_id, GValue * value,
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GParamSpec * pspec)
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{
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/* these properties are all construct-only */
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switch (prop_id) {
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case PROP_NAME_TEMPLATE:
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g_value_set_string (value, GST_PAD_TEMPLATE_NAME_TEMPLATE (object));
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break;
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case PROP_DIRECTION:
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g_value_set_enum (value, GST_PAD_TEMPLATE_DIRECTION (object));
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break;
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case PROP_PRESENCE:
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g_value_set_enum (value, GST_PAD_TEMPLATE_PRESENCE (object));
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break;
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case PROP_CAPS:
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g_value_set_boxed (value, GST_PAD_TEMPLATE_CAPS (object));
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break;
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default:
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G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
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break;
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}
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}
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