Element

GstElement is the abstract base class needed to construct an element that can be used in a GStreamer pipeline. Please refer to the plugin writers guide for more information on creating gstreamer.Element subclasses.

The name of a gstreamer.Element can be get with Element.getName and set with Element.setName. For speed, GST_ELEMENT_NAME() can be used in the core when using the appropriate locking. Do not use this in plug-ins or applications in order to retain ABI compatibility.

Elements can have pads (of the type gstreamer.Pad). These pads link to pads on other elements. gstreamer.Buffer flow between these linked pads. A gstreamer.Element has a GList of gstreamer.Pad structures for all their input (or sink) and output (or source) pads. Core and plug-in writers can add and remove pads with Element.addPad and Element.removePad.

An existing pad of an element can be retrieved by name with Element.getStaticPad. A new dynamic pad can be created using Element.requestPad with a gstreamer.PadTemplate An iterator of all pads can be retrieved with Element.iteratePads.

Elements can be linked through their pads. If the link is straightforward, use the Element.link convenience function to link two elements, or Element.linkMany for more elements in a row. Use Element.linkFiltered to link two elements constrained by a specified set of gstreamer.Caps For finer control, use Element.linkPads and Element.linkPadsFiltered to specify the pads to link on each element by name.

Each element has a state (see GstState). You can get and set the state of an element with Element.getState and Element.setState. Setting a state triggers a GstStateChange To get a string representation of a GstState, use Element.stateGetName.

You can get and set a gstreamer.Clock on an element using Element.getClock and Element.setClock. Some elements can provide a clock for the pipeline if the GST_ELEMENT_FLAG_PROVIDE_CLOCK flag is set. With the Element.provideClock method one can retrieve the clock provided by such an element. Not all elements require a clock to operate correctly. If the GST_ELEMENT_FLAG_REQUIRE_CLOCK|GST_ELEMENT_FLAG_REQUIRE_CLOCK flag is set, a clock should be set on the element with Element.setClock.

Note that clock selection and distribution is normally handled by the toplevel gstreamer.Pipeline so the clock functions are only to be used in very specific situations.

class Element : ObjectGst {}

Constructors

this
this(GstElement* gstElement, bool ownedRef = false)

Sets our main struct and passes it to the parent class.

Members

Functions

abortState
void abortState()

Abort the state change of the element. This function is used by elements that do asynchronous state changes and find out something is wrong.

addOnNoMorePads
gulong addOnNoMorePads(void delegate(Element) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

This signals that the element will not generate more dynamic pads. Note that this signal will usually be emitted from the context of the streaming thread.

addOnPadAdded
gulong addOnPadAdded(void delegate(Pad, Element) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

a new gstreamer.Pad has been added to the element. Note that this signal will usually be emitted from the context of the streaming thread. Also keep in mind that if you add new elements to the pipeline in the signal handler you will need to set them to the desired target state with Element.setState or Element.syncStateWithParent.

addOnPadRemoved
gulong addOnPadRemoved(void delegate(Pad, Element) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

a gstreamer.Pad has been removed from the element

addPad
bool addPad(Pad pad)

Adds a pad (link point) to element. pad's parent will be set to element; see gst_object_set_parent() for refcounting information.

addPropertyDeepNotifyWatch
gulong addPropertyDeepNotifyWatch(string propertyName, bool includeValue)
addPropertyNotifyWatch
gulong addPropertyNotifyWatch(string propertyName, bool includeValue)
callAsync
void callAsync(GstElementCallAsyncFunc func, void* userData, GDestroyNotify destroyNotify)

Calls func from another thread and passes user_data to it. This is to be used for cases when a state change has to be performed from a streaming thread, directly via Element.setState or indirectly e.g. via SEEK events.

caps
void caps(Caps cp)

Set the caps property of an Element.

changeState
GstStateChangeReturn changeState(GstStateChange transition)

Perform transition on element.

continueState
GstStateChangeReturn continueState(GstStateChangeReturn ret)

Commit the state change of the element and proceed to the next pending state if any. This function is used by elements that do asynchronous state changes. The core will normally call this method automatically when an element returned GST_STATE_CHANGE_SUCCESS from the state change function.

createAllPads
void createAllPads()

Creates a pad for each pad template that is always available. This function is only useful during object initialization of subclasses of gstreamer.Element

foreachPad
bool foreachPad(GstElementForeachPadFunc func, void* userData)

Call func with user_data for each of element's pads. func will be called exactly once for each pad that exists at the time of this call, unless one of the calls to func returns FALSE in which case we will stop iterating pads and return early. If new pads are added or pads are removed while pads are being iterated, this will not be taken into account until next time this function is used.

foreachSinkPad
bool foreachSinkPad(GstElementForeachPadFunc func, void* userData)

Call func with user_data for each of element's sink pads. func will be called exactly once for each sink pad that exists at the time of this call, unless one of the calls to func returns FALSE in which case we will stop iterating pads and return early. If new sink pads are added or sink pads are removed while the sink pads are being iterated, this will not be taken into account until next time this function is used.

foreachSrcPad
bool foreachSrcPad(GstElementForeachPadFunc func, void* userData)

Call func with user_data for each of element's source pads. func will be called exactly once for each source pad that exists at the time of this call, unless one of the calls to func returns FALSE in which case we will stop iterating pads and return early. If new source pads are added or source pads are removed while the source pads are being iterated, this will not be taken into account until next time this function is used.

getBaseTime
GstClockTime getBaseTime()

Returns the base time of the element. The base time is the absolute time of the clock when this element was last put to PLAYING. Subtracting the base time from the clock time gives the running time of the element.

getBus
Bus getBus()

Returns the bus of the element. Note that only a gstreamer.Pipeline will provide a bus for the application.

getClock
Clock getClock()

Gets the currently configured clock of the element. This is the clock as was last set with Element.setClock.

getCompatiblePad
Pad getCompatiblePad(Pad pad, Caps caps)

Looks for an unlinked pad to which the given pad can link. It is not guaranteed that linking the pads will work, though it should work in most cases.

getCompatiblePadTemplate
PadTemplate getCompatiblePadTemplate(PadTemplate compattempl)

Retrieves a pad template from element that is compatible with compattempl. Pads from compatible templates can be linked together.

getContext
Context getContext(string contextType)

Gets the context with context_type set on the element or NULL.

getContextUnlocked
Context getContextUnlocked(string contextType)

Gets the context with context_type set on the element or NULL.

getContexts
ListG getContexts()

Gets the contexts set on the element.

getElementStruct
GstElement* getElementStruct(bool transferOwnership = false)

Get the main Gtk struct

getFactory
ElementFactory getFactory()

Retrieves the factory that was used to create this element.

getMetadata
string getMetadata(string key)

Get metadata with key in klass.

getPadTemplate
PadTemplate getPadTemplate(string name)

Retrieves a padtemplate from element with the given name.

getPadTemplateList
ListG getPadTemplateList()

Retrieves a list of the pad templates associated with element. The list must not be modified by the calling code.

getRequestPad
Pad getRequestPad(string name)

Retrieves a pad from the element by name (e.g. "src_\d"). This version only retrieves request pads. The pad should be released with Element.releaseRequestPad.

getStartTime
GstClockTime getStartTime()

Returns the start time of the element. The start time is the running time of the clock when this element was last put to PAUSED.

getState
GstStateChangeReturn getState(out GstState state, out GstState pending, GstClockTime timeout)

Gets the state of the element.

getStaticPad
Pad getStaticPad(string name)

Retrieves a pad from element by name. This version only retrieves already-existing (i.e. 'static') pads.

getStruct
void* getStruct()

the main Gtk struct as a void*

isLockedState
bool isLockedState()

Checks if the state of an element is locked. If the state of an element is locked, state changes of the parent don't affect the element. This way you can leave currently unused elements inside bins. Just lock their state before changing the state from GST_STATE_NULL

iteratePads
Iterator iteratePads()

Retrieves an iterator of element's pads. The iterator should be freed after usage. Also more specialized iterators exists such as Element.iterateSrcPads or Element.iterateSinkPads.

iterateSinkPads
Iterator iterateSinkPads()

Retrieves an iterator of element's sink pads.

iterateSrcPads
Iterator iterateSrcPads()

Retrieves an iterator of element's source pads.

link
bool link(Element dest)

Links src to dest. The link must be from source to destination; the other direction will not be tried. The function looks for existing pads that aren't linked yet. It will request new pads if necessary. Such pads need to be released manually when unlinking. If multiple links are possible, only one is established.

linkFiltered
bool linkFiltered(Element dest, Caps filter)

Links src to dest using the given caps as filtercaps. The link must be from source to destination; the other direction will not be tried. The function looks for existing pads that aren't linked yet. It will request new pads if necessary. If multiple links are possible, only one is established.

linkPads
bool linkPads(string srcpadname, Element dest, string destpadname)

Links the two named pads of the source and destination elements. Side effect is that if one of the pads has no parent, it becomes a child of the parent of the other element. If they have different parents, the link fails.

linkPadsFiltered
bool linkPadsFiltered(string srcpadname, Element dest, string destpadname, Caps filter)

Links the two named pads of the source and destination elements. Side effect is that if one of the pads has no parent, it becomes a child of the parent of the other element. If they have different parents, the link fails. If caps is not NULL, makes sure that the caps of the link is a subset of caps.

linkPadsFull
bool linkPadsFull(string srcpadname, Element dest, string destpadname, GstPadLinkCheck flags)

Links the two named pads of the source and destination elements. Side effect is that if one of the pads has no parent, it becomes a child of the parent of the other element. If they have different parents, the link fails.

location
void location(string set)

* This set's the filename for a filesrc element.

lostState
void lostState()

Brings the element to the lost state. The current state of the element is copied to the pending state so that any call to Element.getState will return GST_STATE_CHANGE_ASYNC.

messageFull
void messageFull(GstMessageType type, GQuark domain, int code, string text, string dbg, string file, string funct, int line)

Post an error, warning or info message on the bus from inside an element.

messageFullWithDetails
void messageFullWithDetails(GstMessageType type, GQuark domain, int code, string text, string dbg, string file, string funct, int line, Structure structure)

Post an error, warning or info message on the bus from inside an element.

noMorePads
void noMorePads()

Use this function to signal that the element does not expect any more pads to show up in the current pipeline. This function should be called whenever pads have been added by the element itself. Elements with GST_PAD_SOMETIMES pad templates use this in combination with autopluggers to figure out that the element is done initializing its pads.

pads
Pad[] pads()

Get's all the pads from an element in a Pad[].

postMessage
bool postMessage(Message message)

Post a message on the element's gstreamer.Bus This function takes ownership of the message; if you want to access the message after this call, you should add an additional reference before calling.

provideClock
Clock provideClock()

Get the clock provided by the given element. > An element is only required to provide a clock in the PAUSED > state. Some elements can provide a clock in other states.

query
bool query(Query query)

Performs a query on the given element.

queryConvert
bool queryConvert(GstFormat srcFormat, long srcVal, GstFormat destFormat, out long destVal)

Queries an element to convert src_val in src_format to dest_format.

queryDuration
long queryDuration()

Queries an element for the stream duration. This is a convenience function for gstreamerD.

queryDuration
bool queryDuration(GstFormat format, out long duration)

Queries an element (usually top-level pipeline or playbin element) for the total stream duration in nanoseconds. This query will only work once the pipeline is prerolled (i.e. reached PAUSED or PLAYING state). The application will receive an ASYNC_DONE message on the pipeline bus when that is the case.

queryPosition
long queryPosition()

Queries an element for the stream position. This is a convenience function for gstreamerD.

queryPosition
bool queryPosition(GstFormat format, out long cur)

Queries an element (usually top-level pipeline or playbin element) for the stream position in nanoseconds. This will be a value between 0 and the stream duration (if the stream duration is known). This query will usually only work once the pipeline is prerolled (i.e. reached PAUSED or PLAYING state). The application will receive an ASYNC_DONE message on the pipeline bus when that is the case.

releaseRequestPad
void releaseRequestPad(Pad pad)

Makes the element free the previously requested pad as obtained with Element.requestPad.

removePad
bool removePad(Pad pad)

Removes pad from element. pad will be destroyed if it has not been referenced elsewhere using gst_object_unparent().

removePropertyNotifyWatch
void removePropertyNotifyWatch(gulong watchId)
requestPad
Pad requestPad(PadTemplate templ, string name, Caps caps)

Retrieves a request pad from the element according to the provided template. Pad templates can be looked up using Element.factoryGetStaticPadTemplates.

seek
int seek(long time_nanoseconds)

For your convenience in gstreamerD: you can seek to the position of the pipeline measured in time_nanoseconds.

seek
bool seek(double rate, GstFormat format, GstSeekFlags flags, GstSeekType startType, long start, GstSeekType stopType, long stop)

Sends a seek event to an element. See Event.newSeek for the details of the parameters. The seek event is sent to the element using Element.sendEvent.

seekSimple
bool seekSimple(GstFormat format, GstSeekFlags seekFlags, long seekPos)

Simple API to perform a seek on the given element, meaning it just seeks to the given position relative to the start of the stream. For more complex operations like segment seeks (e.g. for looping) or changing the playback rate or seeking relative to the last configured playback segment you should use Element.seek.

sendEvent
bool sendEvent(Event event)

Sends an event to an element. If the element doesn't implement an event handler, the event will be pushed on a random linked sink pad for downstream events or a random linked source pad for upstream events.

setBaseTime
void setBaseTime(GstClockTime time)

Set the base time of an element. See Element.getBaseTime.

setBus
void setBus(Bus bus)

Sets the bus of the element. Increases the refcount on the bus. For internal use only, unless you're testing elements.

setClock
bool setClock(Clock clock)

Sets the clock for the element. This function increases the refcount on the clock. Any previously set clock on the object is unreffed.

setContext
void setContext(Context context)

Sets the context of the element. Increases the refcount of the context.

setLockedState
bool setLockedState(bool lockedState)

Locks the state of an element, so state changes of the parent don't affect this element anymore.

setStartTime
void setStartTime(GstClockTime time)

Set the start time of an element. The start time of the element is the running time of the element when it last went to the PAUSED state. In READY or after a flushing seek, it is set to 0.

setState
GstStateChangeReturn setState(GstState state)

Sets the state of the element. This function will try to set the requested state by going through all the intermediary states and calling the class's state change function for each.

syncStateWithParent
bool syncStateWithParent()

Tries to change the state of the element to the same as its parent. If this function returns FALSE, the state of element is undefined.

unlink
void unlink(Element dest)

Unlinks all source pads of the source element with all sink pads of the sink element to which they are linked.

unlinkPads
void unlinkPads(string srcpadname, Element dest, string destpadname)

Unlinks the two named pads of the source and destination elements.

Static functions

getType
GType getType()
makeFromUri
Element makeFromUri(GstURIType type, string uri, string elementname)

Creates an element for handling the given URI.

register
bool register(Plugin plugin, string name, uint rank, GType type)

Create a new elementfactory capable of instantiating objects of the type and add the factory to plugin.

stateChangeReturnGetName
string stateChangeReturnGetName(GstStateChangeReturn stateRet)

Gets a string representing the given state change result.

stateGetName
string stateGetName(GstState state)

Gets a string representing the given state.

Variables

gstElement
GstElement* gstElement;

the main Gtk struct

Inherited Members

From ObjectGst

gstObject
GstObject* gstObject;

the main Gtk struct

getObjectGstStruct
GstObject* getObjectGstStruct(bool transferOwnership = false)

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(ref 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 dbg)

A default error function that uses g_printerr() to display the error message and the optional debug sting..

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() inbetween. 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

doref
ObjectGst doref()

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() inbetween. 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 = cast(ConnectFlags)0)

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.

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