Sets our main struct and passes it to the parent class
Attach the GstControlBinding to the object. If there already was a GstControlBinding for this property it will be replaced. The object will take ownership of the binding.
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 sting.. The default handler will simply print the error string using g_print.
Gets the corresponding GstControlBinding for the property. This should be unreferenced again after use.
Obtain the control-rate for this object. Audio processing GstElement objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() inbetween. The length of the processing segment should be up to control-rate nanoseconds. If the object is not under property control, this will return GST_CLOCK_TIME_NONE. This allows the element to avoid the sub-dividing. The control-rate is not expected to change if the element is in GST_STATE_PAUSED or GST_STATE_PLAYING.
Gets a number of GValues for the given controlled property starting at the requested time. The array values need to hold enough space for n_values of GValue. This function is useful if one wants to e.g. draw a graph of the control curve or apply a control curve sample by sample.
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. Free-function: g_free
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. Free-function: g_free
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. This function is useful if one wants to e.g. draw a graph of the control curve or apply a control curve sample by sample. The values are unboxed and ready to be used. The similar function gst_object_get_g_value_array() returns the array as GValues and is better suites for bindings.
Check if the object has an active controlled properties.
Check if object has an ancestor ancestor somewhere up in the hierarchy. One can e.g. check if a GstElement is inside a GstPipeline.
Removes the corresponding GstControlBinding. If it was the last ref of the binding, it will be disposed.
This function is used to disable the GstController on a property for some time, i.e. gst_controller_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 GstElement objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() inbetween. The length of the processing segment should be up to control-rate nanoseconds. The control-rate should not change if the element is in GST_STATE_PAUSED or GST_STATE_PLAYING.
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 GstControlSources that (maybe) handle them and for the given timestamp. If this function fails, it is most likely the application developers fault. Most probably the control sources are not setup correctly.
Clear the parent of object, removing the associated reference. This function decreases the refcount of object. MT safe. Grabs and releases object's lock.
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 carefull 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. MT safe. This function grabs and releases object's LOCK for getting its path string.
Increments the reference count on object. This function does not take the lock on object because it relies on atomic refcounting. This object returns the input parameter to ease writing
Increase the reference count of object, and possibly remove the floating reference, if object has a floating reference. In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one.
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. Either newobj and the value pointed to by oldobj may be NULL.
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. The unref method should never be called with the LOCK held since this might deadlock the dispose function.
the main Gtk struct
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.
Installs a new property. This is usually done in the class initializer. Note that it is possible to redefine a property in a derived class, by installing a property with the same name. This can be useful at times, e.g. to change the range of allowed values or the default value.
Installs new properties from an array of GParamSpecs. This is usually done in the class initializer. The property id of each property is the index of each GParamSpec in the pspecs array. The property id of 0 is treated specially by GObject and it should not be used to store a GParamSpec. This function should be used if you plan to use a static array of GParamSpecs and g_object_notify_by_pspec(). For instance, this Since 2.26
Looks up the GParamSpec for a property of a class.
Get an array of GParamSpec* for all properties of a class.
Registers property_id as referring to a property with the name name in a parent class or in an interface implemented by oclass. This allows this class to override a property implementation in a parent class or to provide the implementation of a property from an interface. Note Internally, overriding is implemented by creating a property of type GParamSpecOverride; generally operations that query the properties of the object class, such as g_object_class_find_property() or g_object_class_list_properties() will return the overridden property. However, in one case, the construct_properties argument of the constructor virtual function, the GParamSpecOverride is passed instead, so that the param_id field of the GParamSpec will be correct. For virtually all uses, this makes no difference. If you need to get the overridden property, you can call g_param_spec_get_redirect_target(). Since 2.4
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 GParamSpec, but normally g_object_class_override_property() 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. This function is meant to be called from the interface's default vtable initialization function (the class_init member of GTypeInfo.) It must not be called after after class_init has been called for any object types implementing this interface. Since 2.4
Find the GParamSpec 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(). Since 2.4
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(). Since 2.4
Increases the reference count of object.
Decreases the reference count of object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).
Increase the reference count of object, and possibly remove the floating reference, if object has a floating reference. In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one. Since 2.10
Clears a reference to a GObject. object_ptr must not be NULL. If the reference is NULL then this function does nothing. Otherwise, the reference count of the object is decreased and the pointer is set to NULL. This function is threadsafe and modifies the pointer atomically, using memory barriers where needed. A macro is also included that allows this function to be used without pointer casts. Since 2.28
Checks whether object has a floating reference. Since 2.10
This function is intended for GObject implementations to re-enforce a floating object reference. Doing this is seldom required: all GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink(). Since 2.10
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). Note that the weak references created by this method are not thread-safe: they cannot safely be used in one thread if the object's last g_object_unref() might happen in another thread. Use GWeakRef if thread-safety is required.
Removes a weak reference callback to an object.
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. Note that as with g_object_weak_ref(), the weak references created by this method are not thread-safe: they cannot safely be used in one thread if the object's last g_object_unref() might happen in another thread. Use GWeakRef if thread-safety is required.
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().
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. This functionality is intended for binding object to a proxy object managed by another memory manager. This is done with two paired references: the strong reference added by g_object_add_toggle_ref() and a reverse reference to the proxy object which is either a strong reference or weak reference. The setup is that when there are no other references to object, only a weak reference is held in the reverse direction from object to the proxy object, but when there are other references held to object, a strong reference is held. The notify callback is called when the reference from object to the proxy object should be toggled from strong to weak (is_last_ref true) or weak to strong (is_last_ref false). Since a (normal) reference must be held to the object before calling g_object_add_toggle_ref(), the initial state of the reverse link is always strong. Multiple toggle references may be added to the same gobject, however if there are multiple toggle references to an object, none of them will ever be notified until all but one are removed. For this reason, you should only ever use a toggle reference if there is important state in the proxy object. Since 2.8
Removes a reference added with g_object_add_toggle_ref(). The reference count of the object is decreased by one. Since 2.8
Emits a "notify" signal for the property property_name on object. When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.
Emits a "notify" signal for the property specified by pspec on object. This function omits the property name lookup, hence it is faster than g_object_notify(). One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with Since 2.26
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. This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.
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. Duplicate notifications for each property are squashed so that at most one "notify" signal is emitted for each property. It is an error to call this function when the freeze count is zero.
Gets a named field from the objects table of associations (see g_object_set_data()).
Each object carries around a table of associations from strings to pointers. This function lets you set an association. If the object already had an association with that name, the old association will be destroyed.
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. Note that the destroy callback is not called if data is NULL.
Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
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. If the key is not set on the object then dup_func will be called with a NULL argument. Note that dup_func is called while user data of object is locked. This function can be useful to avoid races when multiple threads are using object data on the same key on the same object. Since 2.34
Compares the user data for the key key on object with oldval, and if they are the same, replaces oldval with newval. This is like a typical atomic compare-and-exchange operation, for user data on an object. If the previous value was replaced then ownership of the old value (oldval) is passed to the caller, including the registered destroy notify for it (passed out in old_destroy). Its up to the caller to free this as he wishes, which may or may not include using old_destroy as sometimes replacement should not destroy the object in the normal way. Return: TRUE if the existing value for key was replaced by newval, FALSE otherwise. Since 2.34
This function gets back user data pointers stored via g_object_set_qdata().
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.
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
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. If the quark is not set on the object then dup_func will be called with a NULL argument. Note that dup_func is called while user data of object is locked. This function can be useful to avoid races when multiple threads are using object data on the same key on the same object. Since 2.34
Compares the user data for the key quark on object with oldval, and if they are the same, replaces oldval with newval. This is like a typical atomic compare-and-exchange operation, for user data on an object. If the previous value was replaced then ownership of the old value (oldval) is passed to the caller, including the registered destroy notify for it (passed out in old_destroy). Its up to the caller to free this as he wishes, which may or may not include using old_destroy as sometimes replacement should not destroy the object in the normal way. Return: TRUE if the existing value for quark was replaced by newval, FALSE otherwise. Since 2.34
Sets a property on an object.
Gets a property of an object. value must have been initialized to the expected type of the property (or a type to which the expected type can be transformed) using g_value_init(). In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling g_value_unset(). Note that g_object_get_property() is really intended for language bindings, g_object_get() is much more convenient for C programming.
Sets properties on an object.
Gets properties of an object. In general, a copy is made of the property contents and the caller is responsible for freeing the memory in the appropriate manner for the type, for instance by calling g_free() or g_object_unref(). See g_object_get().
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 g_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.
Releases all references to other objects. This can be used to break reference cycles. This functions should only be called from object system implementations.
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 function 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()).
Since GstObject dereives from GInitiallyUnowned, it also inherits the floating reference. Be aware that functions such as gst_bin_add() and gst_element_add_pad() take ownership of the floating reference.
In contrast to GObject instances, GstObject adds a name property. The functions gst_object_set_name() and gst_object_get_name() are used to set/get the name of the object.
controlled properties
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 values changes for the current stream-time.
What needs to be changed in a GstElement? 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 made the controller to update all gobject properties that are under control with the current values based on timestamp.
What needs to be done in applications? Again it's not a lot to change.
create a GstControlSource. csource = gst_interpolation_control_source_new(); g_object_set (csource, "mode", GST_INTERPOLATION_MODE_LINEAR, NULL);
Attach the GstControlSource 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
Last reviewed on 2012-03-29 (0.11.3)