PadTemplate

Padtemplates describe the possible media types a pad or an elementfactory can handle. This allows for both inspection of handled types before loading the element plugin as well as identifying pads on elements that are not yet created (request or sometimes pads).

Pad and PadTemplates have gstreamer.Caps attached to it to describe the media type they are capable of dealing with. Pad.templateGetCaps or GST_PAD_TEMPLATE_CAPS() are used to get the caps of a padtemplate. It's not possible to modify the caps of a padtemplate after creation.

PadTemplates have a GstPadPresence property which identifies the lifetime of the pad and that can be retrieved with GST_PAD_TEMPLATE_PRESENCE(). Also the direction of the pad can be retrieved from the gstreamer.PadTemplate with GST_PAD_TEMPLATE_DIRECTION().

The GST_PAD_TEMPLATE_NAME_TEMPLATE () is important for GST_PAD_REQUEST pads because it has to be used as the name in the Element.getRequestPad call to instantiate a pad from this template.

Padtemplates can be created with Pad.templateNew or with gst_static_pad_template_get (), which creates a gstreamer.PadTemplate from a gstreamer.StaticPadTemplate that can be filled with the convenient GST_STATIC_PAD_TEMPLATE() macro.

A padtemplate can be used to create a pad (see Pad.newFromTemplate or gst_pad_new_from_static_template ()) or to add to an element class (see gst_element_class_add_static_pad_template ()).

The following code example shows the code to create a pad from a padtemplate.

GstStaticPadTemplate my_template =
GST_STATIC_PAD_TEMPLATE (
"sink",          // the name of the pad
GST_PAD_SINK,    // the direction of the pad
GST_PAD_ALWAYS,  // when this pad will be present
GST_STATIC_CAPS (        // the capabilities of the padtemplate
"audio/x-raw, "
"channels = (int) [ 1, 6 ]"
)
);
void
my_method (void)
{
GstPad *pad;
pad = gst_pad_new_from_static_template (&amp;my_template, "sink");
...
}

The following example shows you how to add the padtemplate to an element class, this is usually done in the class_init of the class:

static void
my_element_class_init (GstMyElementClass *klass)
{
GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);

gst_element_class_add_static_pad_template (gstelement_class, &amp;my_template);
}

class PadTemplate : ObjectGst {

protected

GstPadTemplate* gstPadTemplate;

GstPadTemplate* getPadTemplateStruct(bool transferOwnership);

void* getStruct();

this(GstPadTemplate* gstPadTemplate, bool ownedRef);

static GType getType();

this(string nameTemplate, GstPadDirection direction, GstPadPresence presence, Caps caps);

this(StaticPadTemplate padTemplate, GType padType);

this(string nameTemplate, GstPadDirection direction, GstPadPresence presence, Caps caps, GType padType);

Caps getCaps();

void padCreated(Pad pad);

gulong addOnPadCreated(void delegate(Pad, PadTemplate) dlg, ConnectFlags connectFlags);

}

Constructors

this this(GstPadTemplate* gstPadTemplate, bool ownedRef): Sets our main struct and passes it to the parent class.
this this(string nameTemplate, GstPadDirection direction, GstPadPresence presence, Caps caps): Creates a new pad template with a name according to the given template and with the given arguments.
this this(StaticPadTemplate padTemplate, GType padType): Converts a gstreamer.StaticPadTemplate into a gstreamer.PadTemplate with a type.
this this(string nameTemplate, GstPadDirection direction, GstPadPresence presence, Caps caps, GType padType): Creates a new pad template with a name according to the given template and with the given arguments.

Members

Functions

addOnPadCreated gulong addOnPadCreated(void delegate(Pad, PadTemplate) dlg, ConnectFlags connectFlags): This signal is fired when an element creates a pad from this template.
getCaps Caps getCaps(): Gets the capabilities of the pad template.
getPadTemplateStruct GstPadTemplate* getPadTemplateStruct(bool transferOwnership): Get the main Gtk struct
getStruct void* getStruct(): the main Gtk struct as a void*
padCreated void padCreated(Pad pad): Emit the pad-created signal for this template when created by this pad.

Static functions

getType GType getType()

Variables

gstPadTemplate GstPadTemplate* gstPadTemplate;: the main Gtk struct

Inherited Members

From ObjectGst

gstObject GstObject* gstObject;: the main Gtk struct
getObjectGstStruct GstObject* getObjectGstStruct(bool transferOwnership): Get the main Gtk struct
getStruct void* getStruct(): the main Gtk struct as a void*
getType GType getType()
checkUniqueness bool checkUniqueness(ListG list, string name): 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.
defaultDeepNotify void defaultDeepNotify(ObjectG object, ObjectGst orig, ParamSpec pspec, string[] excludedProps): 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.
refSink void* refSink(void* object): Increase the reference count of object, and possibly remove the floating reference, if object has a floating reference.
replace bool replace(ObjectGst oldobj, ObjectGst newobj): 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.
addControlBinding bool addControlBinding(ControlBinding binding): Attach the gstreamer.ControlBinding to the object. If there already was a gstreamer.ControlBinding for this property it will be replaced.
defaultError void defaultError(ErrorG error, string debug_): A default error function that uses g_printerr() to display the error message and the optional debug string..
getControlBinding ControlBinding getControlBinding(string propertyName): Gets the corresponding gstreamer.ControlBinding for the property. This should be unreferenced again after use.
getControlRate GstClockTime getControlRate(): 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.
getGValueArray bool getGValueArray(string propertyName, GstClockTime timestamp, GstClockTime interval, Value[] values): Gets a number of gobject.Values for the given controlled property starting at the requested time. The array values need to hold enough space for n_values of gobject.Value
getName string getName(): 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.
getParent ObjectGst getParent(): Returns the parent of object. This function increases the refcount of the parent object so you should gst_object_unref() it after usage.
getPathString string getPathString(): Generates a string describing the path of object in the object hierarchy. Only useful (or used) for debugging.
getValue Value getValue(string propertyName, GstClockTime timestamp): Gets the value for the given controlled property at the requested time.
getValueArray bool getValueArray(string propertyName, GstClockTime timestamp, GstClockTime interval, uint nValues, void* values): 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.
hasActiveControlBindings bool hasActiveControlBindings(): Check if the object has active controlled properties.
hasAncestor bool hasAncestor(ObjectGst ancestor): Check if object has an ancestor ancestor somewhere up in the hierarchy. One can e.g. check if a gstreamer.Element is inside a gstreamer.Pipeline
hasAsAncestor bool hasAsAncestor(ObjectGst ancestor): Check if object has an ancestor ancestor somewhere up in the hierarchy. One can e.g. check if a gstreamer.Element is inside a gstreamer.Pipeline
hasAsParent bool hasAsParent(ObjectGst parent): Check if parent is the parent of object. E.g. a gstreamer.Element can check if it owns a given gstreamer.Pad
ref_ ObjectGst ref_(): Increments the reference count on object. This function does not take the lock on object because it relies on atomic refcounting.
removeControlBinding bool removeControlBinding(ControlBinding binding): Removes the corresponding gstreamer.ControlBinding If it was the last ref of the binding, it will be disposed.
setControlBindingDisabled void setControlBindingDisabled(string propertyName, bool disabled): 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.
setControlBindingsDisabled void setControlBindingsDisabled(bool disabled): This function is used to disable all controlled properties of the object for some time, i.e. gst_object_sync_values() will do nothing.
setControlRate void setControlRate(GstClockTime controlRate): 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.
setName bool setName(string name): 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.
setParent bool setParent(ObjectGst parent): 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()).
suggestNextSync GstClockTime suggestNextSync(): Returns a suggestion for timestamps where buffers should be split to get best controller results.
syncValues bool syncValues(GstClockTime timestamp): Sets the properties of the object, according to the gstreamer.ControlSources that (maybe) handle them and for the given timestamp.
unparent void unparent(): Clear the parent of object, removing the associated reference. This function decreases the refcount of object.
unref void unref(): 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.
addOnDeepNotify gulong addOnDeepNotify(void delegate(ObjectGst, ParamSpec, ObjectGst) dlg, ConnectFlags connectFlags): 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.

gstreamer PadTemplate classes

PadTemplate