Table of Contents
Warning, this part describes 0.10 and is outdated.
Sometimes object properties are not powerful enough to control the parameters that affect the behaviour of your element. When this is the case you can mark these parameters as being Controllable. Aware applications can use the controller subsystem to dynamically adjust the property values over time.
The controller subsystem is contained within the
gstcontroller
library. You need to include the header in
your element's source file:
... #include <gst/gst.h> #include <gst/controller/gstcontroller.h> ...
Even though the gstcontroller
library may be linked into
the host application, you should make sure it is initialized in your
plugin_init
function:
static gboolean plugin_init (GstPlugin *plugin) { ... /* initialize library */ gst_controller_init (NULL, NULL); ... }
It makes no sense for all GObject parameter to be real-time controlled.
Therefore the next step is to mark controllable parameters.
This is done by using the special flag GST_PARAM_CONTROLLABLE
.
when setting up GObject params in the _class_init
method.
g_object_class_install_property (gobject_class, PROP_FREQ, g_param_spec_double ("freq", "Frequency", "Frequency of test signal", 0.0, 20000.0, 440.0, G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));