gstreamer/docs/gst/tmpl/gstcaps.sgml
David Schleef 7e6017aac1 docs/gst/tmpl/gstcaps.sgml: Fix stuff that mentions GstProps
Original commit message from CVS:
* docs/gst/tmpl/gstcaps.sgml:  Fix stuff that mentions GstProps
* docs/gst/tmpl/gstpadtemplate.sgml: same
* docs/gst/tmpl/gstreamer-unused.sgml: Remove GstProps
* gst/gstobject.c: (gst_object_set_name_default): Do the memleak
fixing dance.
* gst/gstutils.c: Remove disabled code that uses GstProps.
* gst/registries/gstxmlregistry.h: same
* docs/random/ds/0.9-suggested-changes: random notes
2004-02-11 20:16:33 +00:00

218 lines
4.1 KiB
Text

<!-- ##### SECTION Title ##### -->
GstCaps
<!-- ##### SECTION Short_Description ##### -->
Capabilities of pads
<!-- ##### SECTION Long_Description ##### -->
<para>
GstCaps is used to attach capabilities to a pad. Capabilities are made of
a mime-type and a set of properties. GstCaps can be named and chained into
a list, which is then a GstCaps on its own.
</para>
<para>
GstCaps are created with gst_caps_new_simpl(), which takes a mime type and
a list of arguments in sets of 3, terminated with NULL. Each set of 3
arguments is the name of a field, the GType of the field, and the value
of the field. The following example shows how to create a GstCaps.
<programlisting>
GstCaps *caps;
caps = gst_caps_new (
"audio/x-raw-int", /* mime type */
"channels", G_TYPE_INT, 5,
NULL);
</programlisting>
The following code example is equivalent to the above example:
<programlisting>
GstCaps *caps;
caps = gst_caps_from_string ("audio/x-raw-int, channels = (int) 5");
</programlisting>
</para>
<para>
GstCaps are refcounted with gst_caps_ref() and gst_caps_unref().
</para>
<para>
GstCaps can be chained with the gst_caps_append(), gst_caps_prepend() and
gst_caps_chain() functions. Use gst_caps_get_by_name() to get a named caps
structure from a chained list.
</para>
<para>
To get the properties of a caps structure the functions
gst_caps_get_boolean(), gst_caps_get_fourcc_int(), gst_caps_get_int(),
gst_caps_get_string(), gst_caps_get_float(), which all take a property name as an argument.
</para>
<para>
The fields of the caps structure can be modified with gst_caps_set_simple,
which takes the caps structure to be modified, a list of arguments in
sets of 3, terminated by NULL. The format of these arguments is the
same as above.
<programlisting>
GstCaps *caps;
....
gst_caps_set_simple (caps, "channels", G_TYPE_INT, 20, NULL);
</programlisting>
</para>
<para>
before modifying a GstCaps, it is a good idea to make a copy if it first with
gst_caps_copy_on_write(). This will copy the GstCaps if the refcount is &gt;1.
</para>
<para>
If you need a unique instance of a GstCaps you can use the convenient
GST_CAPS_FACTORY() macro as shown below.
<programlisting>
GstStaticCaps my_caps = GST_STATIC_CAPS (
"audio/x-raw-float, "
"channels = (int) 5; "
"audio/x-raw-int, "
"channels = (int) 5"
)
)
void
some_function (void)
{
GstCaps *caps = gst_caps_copy (gst_static_caps_get (&amp;my_caps));
...
}
</programlisting>
</para>
<para>
If you want to check if a link between source and destination caps
is always possible, use gst_caps_is_always_compatible(), which returns
a boolean.
If you want to check if a link between source and destination caps
might be possible, use gst_caps_intersect(), which returns an intersection
of the capabilities.
</para>
<!-- ##### SECTION See_Also ##### -->
<para>
#GstStructure, #GstPad
</para>
<!-- ##### MACRO GST_TYPE_CAPS ##### -->
<para>
The GType of the caps boxed type, for use in GValues.
</para>
<!-- ##### STRUCT GstCaps ##### -->
<para>
The gstcaps structure
</para>
@type:
@flags:
@structs:
<!-- ##### FUNCTION gst_caps_copy ##### -->
<para>
</para>
@caps:
@Returns:
<!-- ##### FUNCTION gst_caps_copy_1 ##### -->
<para>
</para>
@caps:
@Returns:
<!-- ##### FUNCTION gst_caps_append ##### -->
<para>
</para>
@caps1:
@caps2:
<!-- # Unused Parameters # -->
@caps:
@capstoadd:
@Returns:
<!-- ##### FUNCTION gst_caps_replace ##### -->
<para>
</para>
@caps:
@newcaps:
<!-- # Unused Parameters # -->
@oldcaps:
<!-- ##### FUNCTION gst_caps_is_always_compatible ##### -->
<para>
</para>
@caps1:
@caps2:
@Returns:
<!-- # Unused Parameters # -->
@fromcaps:
@tocaps:
<!-- ##### FUNCTION gst_caps_normalize ##### -->
<para>
</para>
@caps:
@Returns:
<!-- ##### FUNCTION gst_caps_intersect ##### -->
<para>
</para>
@caps1:
@caps2:
@Returns:
<!-- ##### FUNCTION gst_caps_save_thyself ##### -->
<para>
</para>
@caps:
@parent:
@Returns:
<!-- ##### FUNCTION gst_caps_load_thyself ##### -->
<para>
</para>
@parent:
@Returns:
<!-- ##### FUNCTION gst_caps_union ##### -->
<para>
</para>
@caps1:
@caps2:
@Returns: