GstObject provides a root for the object hierarchy tree filed in by the GStreamer library. It is currently a thin wrapper on top of GInitiallyUnowned It is an abstract class that is not very usable on its own.
GstObject gives us basic refcounting, parenting functionality and locking. Most of the functions are just extended for special GStreamer needs and can be found under the same name in the base class of GstObject which is GObject (e.g. g_object_ref() becomes gst_object_ref()).
Controlled properties offers a lightweight way to adjust gobject properties over stream-time. It works by using time-stamped value pairs that are queued for element-properties. At run-time the elements continuously pull value changes for the current stream-time.
What needs to be changed in a gstreamer.Element? Very little - it is just two steps to make a plugin controllable!
* mark gobject-properties paramspecs that make sense to be controlled, by GST_PARAM_CONTROLLABLE.
* when processing data (get, chain, loop function) at the beginning call gst_object_sync_values(element,timestamp). This will make the controller update all GObject properties that are under its control with the current values based on the timestamp.
What needs to be done in applications? Again it's not a lot to change.
* create a gstreamer.ControlSource csource = gst_interpolation_control_source_new (); g_object_set (csource, "mode", GST_INTERPOLATION_MODE_LINEAR, NULL);
* Attach the gstreamer.ControlSource on the controller to a property. gst_object_add_control_binding (object, gst_direct_control_binding_new (object, "prop1", csource));
* Set the control values gst_timed_value_control_source_set ((GstTimedValueControlSource *)csource,0 * GST_SECOND, value1); gst_timed_value_control_source_set ((GstTimedValueControlSource *)csource,1 * GST_SECOND, value2);
* start your pipeline
Sets our main struct and passes it to the parent class.
The deep notify signal is used to be notified of property changes. It is typically attached to the toplevel bin to receive notifications from all the elements contained in that bin.
A default error function that uses g_printerr() to display the error message and the optional debug string..
Gets the corresponding gstreamer.ControlBinding for the property. This should be unreferenced again after use.
Obtain the control-rate for this object. Audio processing gstreamer.Element objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() in between. The length of the processing segment should be up to control-rate nanoseconds.
Returns a copy of the name of object. Caller should g_free() the return value after usage. For a nameless object, this returns NULL, which you can safely g_free() as well.
Get the main Gtk struct
Returns the parent of object. This function increases the refcount of the parent object so you should gst_object_unref() it after usage.
Generates a string describing the path of object in the object hierarchy. Only useful (or used) for debugging.
the main Gtk struct as a void*
Gets the value for the given controlled property at the requested time.
Gets a number of values for the given controlled property starting at the requested time. The array values need to hold enough space for n_values of the same type as the objects property's type.
Check if the object has active controlled properties.
Increments the reference count on object. This function does not take the lock on object because it relies on atomic refcounting.
Removes the corresponding gstreamer.ControlBinding If it was the last ref of the binding, it will be disposed.
This function is used to disable the control bindings on a property for some time, i.e. gst_object_sync_values() will do nothing for the property.
This function is used to disable all controlled properties of the object for some time, i.e. gst_object_sync_values() will do nothing.
Change the control-rate for this object. Audio processing gstreamer.Element objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() in between. The length of the processing segment should be up to control-rate nanoseconds.
Sets the name of object, or gives object a guaranteed unique name (if name is NULL). This function makes a copy of the provided name, so the caller retains ownership of the name it sent.
Sets the parent of object to parent. The object's reference count will be incremented, and any floating reference will be removed (see gst_object_ref_sink()).
Returns a suggestion for timestamps where buffers should be split to get best controller results.
Sets the properties of the object, according to the gstreamer.ControlSources that (maybe) handle them and for the given timestamp.
Clear the parent of object, removing the associated reference. This function decreases the refcount of object.
Decrements the reference count on object. If reference count hits zero, destroy object. This function does not take the lock on object as it relies on atomic refcounting.
Checks to see if there is any object named name in list. This function does not do any locking of any kind. You might want to protect the provided list with the lock of the owner of the list. This function will lock each GstObject in the list to compare the name, so be careful when passing a list with a locked object.
A default deep_notify signal callback for an object. The user data should contain a pointer to an array of strings that should be excluded from the notify. The default handler will print the new value of the property using g_print.
Increase the reference count of object, and possibly remove the floating reference, if object has a floating reference.
Atomically modifies a pointer to point to a new object. The reference count of oldobj is decreased and the reference count of newobj is increased.
the main Gtk struct
the main Gtk struct
Get the main Gtk struct
the main Gtk struct as a void*
Gets a D Object from the objects table of associations.
The notify signal is emitted on an object when one of its properties has been changed. Note that getting this signal doesn't guarantee that the value of the property has actually changed, it may also be emitted when the setter for the property is called to reinstate the previous value.
Find the gobject.ParamSpec with the given name for an interface. Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().
Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created gobject.ParamSpec, but normally ObjectClass.overrideProperty will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property.
Lists the properties of an interface.Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().
Increases the reference count of the object by one and sets a callback to be called when all other references to the object are dropped, or when this is already the last reference to the object and another reference is established.
Adds a weak reference from weak_pointer to object to indicate that the pointer located at weak_pointer_location is only valid during the lifetime of object. When the object is finalized, weak_pointer will be set to NULL.
Creates a binding between source_property on source and target_property on target. Whenever the source_property is changed the target_property is updated using the same value. For instance:
Complete version of g_object_bind_property().
Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.
This is a variant of g_object_get_data() which returns a 'duplicate' of the value. dup_func defines the meaning of 'duplicate' in this context, it could e.g. take a reference on a ref-counted object.
This is a variant of g_object_get_qdata() which returns a 'duplicate' of the value. dup_func defines the meaning of 'duplicate' in this context, it could e.g. take a reference on a ref-counted object.
Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one notify signal is emitted for each property modified while the object is frozen.
Gets a named field from the objects table of associations (see g_object_set_data()).
Gets a property of an object.
This function gets back user data pointers stored via g_object_set_qdata().
Gets properties of an object.
Gets n_properties properties for an object. Obtained properties will be set to values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.
Checks whether object has a floating[floating-ref] reference.
Emits a "notify" signal for the property property_name on object.
Emits a "notify" signal for the property specified by pspec on object.
Increases the reference count of object.
Increase the reference count of object, and possibly remove the floating[floating-ref] reference, if object has a floating reference.
Removes a reference added with g_object_add_toggle_ref(). The reference count of the object is decreased by one.
Removes a weak reference from object that was previously added using g_object_add_weak_pointer(). The weak_pointer_location has to match the one used with g_object_add_weak_pointer().
Compares the user data for the key key on object with oldval, and if they are the same, replaces oldval with newval.
Compares the user data for the key quark on object with oldval, and if they are the same, replaces oldval with newval.
Releases all references to other objects. This can be used to break reference cycles.
Each object carries around a table of associations from strings to pointers. This function lets you set an association.
Like g_object_set_data() except it adds notification for when the association is destroyed, either by setting it to a different value or when the object is destroyed.
Sets a property on an object.
This sets an opaque, named pointer on an object. The name is specified through a GQuark (retrived e.g. via g_quark_from_static_string()), and the pointer can be gotten back from the object with g_object_get_qdata() until the object is finalized. Setting a previously set user data pointer, overrides (frees) the old pointer set, using NULL as pointer essentially removes the data stored.
This function works like g_object_set_qdata(), but in addition, a void (*destroy) (gpointer) function may be specified which is called with data as argument when the object is finalized, or the data is being overwritten by a call to g_object_set_qdata() with the same quark.
Sets properties on an object.
Sets n_properties properties for an object. Properties to be set will be taken from values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.
Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
This function gets back user data pointers stored via g_object_set_qdata() and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example:
Reverts the effect of a previous call to g_object_freeze_notify(). The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted.
Decreases the reference count of object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).
This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling Closure.invalidate on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, g_object_ref() and g_object_unref() are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.
Adds a weak reference callback to an object. Weak references are used for notification when an object is finalized. They are called "weak references" because they allow you to safely hold a pointer to an object without calling g_object_ref() (g_object_ref() adds a strong reference, that is, forces the object to stay alive).
Removes a weak reference callback to an object.
Clears a reference to a GObject