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>Chapter 5. Elements</TD
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><A
NAME="section-elements-create"
>5.2. Creating a <CODE
CLASS="classname"
>GstElement</CODE
></A
></H1
><P
> The simplest way to create an element is to use <A
HREF="http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/GstElementFactory.html#gst-element-factory-make"
TARGET="_top"
><CODE
CLASS="function"
>gst_element_factory_make
()</CODE
></A
>. This function takes a factory name and an
element name for the newly created element. The name of the element
is something you can use later on to look up the element in a bin,
for example. The name will also be used in debug output. You can
pass <CODE
CLASS="symbol"
>NULL</CODE
> as the name argument to get a unique,
default name.
</P
><P
> When you don't need the element anymore, you need to unref it using
<A
HREF="http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/GstObject.html#gst-object-unref"
TARGET="_top"
><CODE
CLASS="function"
>gst_object_unref
()</CODE
></A
>. This decreases the reference count for the
element by 1. An element has a refcount of 1 when it gets created.
An element gets destroyed completely when the refcount is decreased
to 0.
</P
><P
> The following example
<A
NAME="AEN417"
HREF="#FTN.AEN417"
><SPAN
CLASS="footnote"
>[1]</SPAN
></A
>
shows how to create an element named
<SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>source</I
></SPAN
> from the element factory named
<SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>fakesrc</I
></SPAN
>. It checks if the creation succeeded.
After checking, it unrefs the element.
</P
><PRE
CLASS="programlisting"
> #include <gst/gst.h>
int
main (int argc,
char *argv[])
{
GstElement *element;
/* init GStreamer */
gst_init (&argc, &argv);
/* create element */
element = gst_element_factory_make ("fakesrc", "source");
if (!element) {
g_print ("Failed to create element of type 'fakesrc'\n");
return -1;
}
gst_object_unref (GST_OBJECT (element));
return 0;
}
</PRE
><P
>
<CODE
CLASS="function"
>gst_element_factory_make</CODE
> is actually a shorthand
for a combination of two functions. A <A
HREF="http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/GstElement.html"
TARGET="_top"
><CODE
CLASS="classname"
>GstElement</CODE
></A
>
object is created from a factory. To create the element, you have to
get access to a <A
HREF="http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/GstElementFactory.html"
TARGET="_top"
><CODE
CLASS="classname"
>GstElementFactory</CODE
></A
>
object using a unique factory name. This is done with <A
HREF="http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/GstElementFactory.html#gst-element-factory-find"
TARGET="_top"
><CODE
CLASS="function"
>gst_element_factory_find
()</CODE
></A
>.
</P
><P
>
The following code fragment is used to get a factory that can be used
to create the <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>fakesrc</I
></SPAN
> element, a fake data source.
The function <A
HREF="http://gstreamer.freedesktop.org/data/doc/gstreamer/stable/gstreamer/html/GstElementFactory.html#gst-element-factory-create"
TARGET="_top"
><CODE
CLASS="function"
>gst_element_factory_create
()</CODE
></A
> will use the element factory to create an
element with the given name.
</P
><PRE
CLASS="programlisting"
> #include <gst/gst.h>
int
main (int argc,
char *argv[])
{
GstElementFactory *factory;
GstElement * element;
/* init GStreamer */
gst_init (&argc, &argv);
/* create element, method #2 */
factory = gst_element_factory_find ("fakesrc");
if (!factory) {
g_print ("Failed to find factory of type 'fakesrc'\n");
return -1;
}
element = gst_element_factory_create (factory, "source");
if (!element) {
g_print ("Failed to create element, even though its factory exists!\n");
return -1;
}
gst_object_unref (GST_OBJECT (element));
return 0;
}
</PRE
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><H3
CLASS="FOOTNOTES"
>Notes</H3
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><A
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HREF="section-elements-create.html#AEN417"
><SPAN
CLASS="footnote"
>[1]</SPAN
></A
></TD
><TD
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WIDTH="95%"
><P
> The code for this example is automatically extracted from
the documentation and built under <TT
CLASS="filename"
>examples/manual</TT
>
in the GStreamer tarball.
</P
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