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GStreamer 0.10 Library Reference Manual | ![]() |
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#include <gst/controller/gstcontroller.h> GstController; enum GstInterpolateMode; gboolean gst_controller_init (int *argc, char ***argv); GstController* gst_controller_new (GObject *object, ...); GstController* gst_controller_new_list (GObject *object, GList *list); GstController* gst_controller_new_valist (GObject *object, va_list var_args); gboolean gst_controller_remove_properties (GstController *self, ...); gboolean gst_controller_remove_properties_list (GstController *self, GList *list); gboolean gst_controller_remove_properties_valist (GstController *self, va_list var_args); gboolean gst_controller_set (GstController *self, gchar *property_name, GstClockTime timestamp, GValue *value); gboolean gst_controller_set_from_list (GstController *self, gchar *property_name, GSList *timedvalues); gboolean gst_controller_unset (GstController *self, gchar *property_name, GstClockTime timestamp); gboolean gst_controller_unset_all (GstController *self, gchar *property_name); GValue* gst_controller_get (GstController *self, gchar *property_name, GstClockTime timestamp); const GList* gst_controller_get_all (GstController *self, gchar *property_name); gboolean gst_controller_sync_values (GstController *self, GstClockTime timestamp); gboolean gst_controller_get_value_arrays (GstController *self, GstClockTime timestamp, GSList *value_arrays); gboolean gst_controller_get_value_array (GstController *self, GstClockTime timestamp, GstValueArray *value_array); gboolean gst_controller_set_interpolation_mode (GstController *self, gchar *property_name, GstInterpolateMode mode); #define GST_PARAM_CONTROLLABLE
The controller subsystem 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 continously 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 its not a lot to change.
first put some properties under control, by calling controller = g_object_control_properties(object, "prop1", "prop2",...);
set how the controller will smooth inbetween values. gst_controller_set_interpolation_mode(controller,"prop1",mode);
set key values gst_controller_set (controller, "prop1" ,0 * GST_SECOND, value1); gst_controller_set (controller, "prop1" ,1 * GST_SECOND, value2);
start your pipeline
typedef enum { GST_INTERPOLATE_NONE, GST_INTERPOLATE_TRIGGER, GST_INTERPOLATE_LINEAR, GST_INTERPOLATE_QUADRATIC, GST_INTERPOLATE_CUBIC, GST_INTERPOLATE_USER } GstInterpolateMode;
The various interpolation modes available.
gboolean gst_controller_init (int *argc, char ***argv);
Initializes the use of the controller library. Suggested to be called right after gst_init().
argc : | pointer to the commandline argument count |
argv : | pointer to the commandline argument values |
Returns : | the TRUE for success. |
GstController* gst_controller_new (GObject *object, ...);
Creates a new GstController for the given object's properties
object : | the object of which some properties should be controlled |
... : | NULL terminated list of property names that should be controlled |
Returns : | the new controller. |
GstController* gst_controller_new_list (GObject *object, GList *list);
Creates a new GstController for the given object's properties
object : | the object of which some properties should be controlled |
list : | list of property names that should be controlled |
Returns : | the new controller. |
GstController* gst_controller_new_valist (GObject *object, va_list var_args);
Creates a new GstController for the given object's properties
object : | the object of which some properties should be controlled |
var_args : | NULL terminated list of property names that should be controlled |
Returns : | the new controller. |
gboolean gst_controller_remove_properties (GstController *self, ...);
Removes the given object properties from the controller
self : | the controller object from which some properties should be removed |
... : | NULL terminated list of property names that should be removed |
Returns : | FALSE if one of the given property isn't handled by the controller, TRUE otherwise |
gboolean gst_controller_remove_properties_list (GstController *self, GList *list);
Removes the given object properties from the controller
self : | the controller object from which some properties should be removed |
list : | GList of property names that should be removed |
Returns : | FALSE if one of the given property isn't handled by the controller, TRUE otherwise |
gboolean gst_controller_remove_properties_valist (GstController *self, va_list var_args);
Removes the given object properties from the controller
self : | the controller object from which some properties should be removed |
var_args : | NULL terminated list of property names that should be removed |
Returns : | FALSE if one of the given property isn't handled by the controller, TRUE otherwise |
gboolean gst_controller_set (GstController *self, gchar *property_name, GstClockTime timestamp, GValue *value);
Set the value of given controller-handled property at a certain time.
self : | the controller object which handles the properties |
property_name : | the name of the property to set |
timestamp : | the time the control-change is schedules for |
value : | the control-value |
Returns : | FALSE if the values couldn't be set (ex : properties not handled by controller), TRUE otherwise |
gboolean gst_controller_set_from_list (GstController *self, gchar *property_name, GSList *timedvalues);
Sets multiple timed values at once.
self : | the controller object which handles the properties |
property_name : | the name of the property to set |
timedvalues : | a list with GstTimedValue items |
Returns : | FALSE if the values couldn't be set (ex : properties not handled by controller), TRUE otherwise |
gboolean gst_controller_unset (GstController *self, gchar *property_name, GstClockTime timestamp);
Used to remove the value of given controller-handled property at a certain time.
self : | the controller object which handles the properties |
property_name : | the name of the property to unset |
timestamp : | the time the control-change should be removed from |
Returns : | FALSE if the values couldn't be unset (ex : properties not handled by controller), TRUE otherwise |
gboolean gst_controller_unset_all (GstController *self, gchar *property_name);
Used to remove all time-stamped values of given controller-handled property
self : | the controller object which handles the properties |
property_name : | the name of the property to unset |
Returns : | FALSE if the values couldn't be unset (ex : properties not handled by controller), TRUE otherwise |
Since 0.10.5
GValue* gst_controller_get (GstController *self, gchar *property_name, GstClockTime timestamp);
Gets the value for the given controller-handled property at the requested time.
self : | the controller object which handles the properties |
property_name : | the name of the property to get |
timestamp : | the time the control-change should be read from |
Returns : | the GValue of the property at the given time, or NULL if the property isn't handled by the controller |
const GList* gst_controller_get_all (GstController *self, gchar *property_name);
Returns a read-only copy of the list of GstTimedValue for the given property. Free the list after done with it.
self : | the controller to get the list from |
property_name : | the name of the property to get the list for |
Returns : | a copy of the list, or NULL if the property isn't handled by the controller |
gboolean gst_controller_sync_values (GstController *self, GstClockTime timestamp);
Sets the properties of the element, according to the controller that (maybe) handles them and for the given timestamp.
self : | the controller that handles the values |
timestamp : | the time that should be processed |
Returns : | TRUE if the controller values could be applied to the object properties, FALSE otherwise |
gboolean gst_controller_get_value_arrays (GstController *self, GstClockTime timestamp, GSList *value_arrays);
Function to be able to get an array of values for one or more given element properties.
If the GstValueArray->values array in list nodes is NULL, it will be created by the function. The type of the values in the array are the same as the property's type.
self : | the controller that handles the values |
timestamp : | the time that should be processed |
value_arrays : | list to return the control-values in |
Returns : | TRUE if the given array(s) could be filled, FALSE otherwise |
gboolean gst_controller_get_value_array (GstController *self, GstClockTime timestamp, GstValueArray *value_array);
Function to be able to get an array of values for one element properties
If the GstValueArray->values array is NULL, it will be created by the function. The type of the values in the array are the same as the property's type.
self : | the controller that handles the values |
timestamp : | the time that should be processed |
value_array : | array to put control-values in |
Returns : | TRUE if the given array(s) could be filled, FALSE otherwise |
gboolean gst_controller_set_interpolation_mode (GstController *self, gchar *property_name, GstInterpolateMode mode);
Sets the given interpolation mode on the given property.
self : | the controller object |
property_name : | the name of the property for which to change the interpolation |
mode : | interpolation mode |
Returns : | TRUE if the property is handled by the controller, FALSE otherwise |