Task

#GstTask is used by #GstElement and #GstPad to provide the data passing threads in a #GstPipeline.

A #GstPad will typically start a #GstTask to push or pull data to/from the peer pads. Most source elements start a #GstTask to push data. In some cases a demuxer element can start a #GstTask to pull data from a peer element. This is typically done when the demuxer can perform random access on the upstream peer element for improved performance.

Although convenience functions exist on #GstPad to start/pause/stop tasks, it might sometimes be needed to create a #GstTask manually if it is not related to a #GstPad.

Before the #GstTask can be run, it needs a #GRecMutex that can be set with gst.task.Task.setLock.

The task can be started, paused and stopped with gst.task.Task.start, gst.task.Task.pause and gst.task.Task.stop respectively or with the gst.task.Task.setState function.

A #GstTask will repeatedly call the #GstTaskFunction with the user data that was provided when creating the task with gst.task.Task.new_. While calling the function it will acquire the provided lock. The provided lock is released when the task pauses or stops.

Stopping a task with gst.task.Task.stop will not immediately make sure the task is not running anymore. Use gst.task.Task.join to make sure the task is completely stopped and the thread is stopped.

After creating a #GstTask, use gst.object.ObjectGst.unref to free its resources. This can only be done when the task is not running anymore.

Task functions can send a #GstMessage to send out-of-band data to the application. The application can receive messages from the #GstBus in its mainloop.

For debugging purposes, the task will configure its object name as the thread name on Linux. Please note that the object name should be configured before the task is started; changing the object name after the task has been started, has no effect on the thread name.

class Task : ObjectGst {

this(gst.types.TaskFunction func);

static void cleanupAll();

gst.task_pool.TaskPool getPool();

gst.types.TaskState getState();

bool join();

bool pause();

bool resume();

void setEnterCallback(gst.types.TaskThreadFunc enterFunc);

void setLeaveCallback(gst.types.TaskThreadFunc leaveFunc);

void setLock(glib.rec_mutex.RecMutex mutex);

void setPool(gst.task_pool.TaskPool pool);

bool setState(gst.types.TaskState state);

bool start();

bool stop();

}

Constructors

this this(gst.types.TaskFunction func): Create a new Task that will repeatedly call the provided func with user_data as a parameter. Typically the task will run in a new thread.

Members

Functions

getPool gst.task_pool.TaskPool getPool(): Get the #GstTaskPool that this task will use for its streaming threads.
getState gst.types.TaskState getState(): Get the current state of the task.
join bool join(): Joins task. After this call, it is safe to unref the task and clean up the lock set with gst.task.Task.setLock.
pause bool pause(): Pauses task. This method can also be called on a task in the stopped state, in which case a thread will be started and will remain in the paused state. This function does not wait for the task to complete the paused state.
resume bool resume(): Resume task in case it was paused. If the task was stopped, it will remain in that state and this function will return false.
setEnterCallback void setEnterCallback(gst.types.TaskThreadFunc enterFunc): Call enter_func when the task function of task is entered. user_data will be passed to enter_func and notify will be called when user_data is no longer referenced.
setLeaveCallback void setLeaveCallback(gst.types.TaskThreadFunc leaveFunc): Call leave_func when the task function of task is left. user_data will be passed to leave_func and notify will be called when user_data is no longer referenced.
setLock void setLock(glib.rec_mutex.RecMutex mutex): Set the mutex used by the task. The mutex will be acquired before calling the #GstTaskFunction.
setPool void setPool(gst.task_pool.TaskPool pool): Set pool as the new GstTaskPool for task. Any new streaming threads that will be created by task will now use pool.
setState bool setState(gst.types.TaskState state): Sets the state of task to state.
start bool start(): Starts task. The task must have a lock associated with it using gst.task.Task.setLock or this function will return false.
stop bool stop(): Stops task. This method merely schedules the task to stop and will not wait for the task to have completely stopped. Use gst.task.Task.join to stop and wait for completion.

Static functions

cleanupAll void cleanupAll(): Wait for all tasks to be stopped. This is mainly used internally to ensure proper cleanup of internal data structures in test suites.

Inherited Members

From ObjectGst

checkUniqueness bool checkUniqueness(gst.object.ObjectGst[] 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(gobject.object.ObjectG object, gst.object.ObjectGst orig, gobject.param_spec.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.
replace bool replace(gst.object.ObjectGst oldobj, gst.object.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(gst.control_binding.ControlBinding binding): Attach the #GstControlBinding to the object. If there already was a #GstControlBinding for this property it will be replaced.
defaultError void defaultError(glib.error.ErrorG error, string debug_): A default error function that uses glib.global.printerr to display the error message and the optional debug string..
getControlBinding gst.control_binding.ControlBinding getControlBinding(string propertyName): Gets the corresponding #GstControlBinding for the property. This should be unreferenced again after use.
getControlRate gst.types.ClockTime getControlRate(): 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.ObjectGst.syncValues in between. The length of the processing segment should be up to control-rate nanoseconds.
getGValueArray bool getGValueArray(string propertyName, gst.types.ClockTime timestamp, gst.types.ClockTime interval, gobject.value.Value[] values): 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.
getName string getName(): Returns a copy of the name of object. Caller should glib.global.gfree the return value after usage. For a nameless object, this returns null, which you can safely glib.global.gfree as well.
getParent gst.object.ObjectGst getParent(): Returns the parent of object. This function increases the refcount of the parent object so you should gst.object.ObjectGst.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 gobject.value.Value getValue(string propertyName, gst.types.ClockTime timestamp): Gets the value for the given controlled property at the requested time.
hasActiveControlBindings bool hasActiveControlBindings(): Check if the object has active controlled properties.
hasAncestor bool hasAncestor(gst.object.ObjectGst ancestor): Check if object has an ancestor ancestor somewhere up in the hierarchy. One can e.g. check if a #GstElement is inside a #GstPipeline.
hasAsAncestor bool hasAsAncestor(gst.object.ObjectGst ancestor): Check if object has an ancestor ancestor somewhere up in the hierarchy. One can e.g. check if a #GstElement is inside a #GstPipeline.
hasAsParent bool hasAsParent(gst.object.ObjectGst parent): Check if parent is the parent of object. E.g. a #GstElement can check if it owns a given #GstPad.
removeControlBinding bool removeControlBinding(gst.control_binding.ControlBinding binding): Removes the corresponding #GstControlBinding. 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.ObjectGst.syncValues 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.ObjectGst.syncValues will do nothing.
setControlRate void setControlRate(gst.types.ClockTime controlRate): 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.ObjectGst.syncValues 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(gst.object.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.ObjectGst.refSink).
suggestNextSync gst.types.ClockTime suggestNextSync(): Returns a suggestion for timestamps where buffers should be split to get best controller results.
syncValues bool syncValues(gst.types.ClockTime timestamp): Sets the properties of the object, according to the #GstControlSources 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.
connectDeepNotify ulong connectDeepNotify(string detail, T callback, Flag!"After" after): Connect to DeepNotify signal.

gst task classes

Task