/* GStreamer * * Copyright (C) 2007 Sebastian Dröge <slomo@circular-chaos.org> * * gstcontrolsource.c: Interface declaration for control sources * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. */ /** * SECTION:gstcontrolsource * @short_description: base class for control source sources * * The #GstControlSource is a base class for control value sources that could * be used by #GstController to get timestamp-value pairs. * * A #GstControlSource is used by first getting an instance, binding it to a * #GParamSpec (for example by using gst_controller_set_control_source()) and * then by having it used by the #GstController or calling * gst_control_source_get_value() or gst_control_source_get_value_array(). * * For implementing a new #GstControlSource one has to implement a * #GstControlSourceBind method, which will depending on the #GParamSpec set up * the control source for use and sets the #GstControlSourceGetValue and * #GstControlSourceGetValueArray functions. These are then used by * gst_control_source_get_value() or gst_control_source_get_value_array() * to get values for specific timestamps. * */ #include "gst_private.h" #include <glib-object.h> #include <gst/gst.h> #include "gstcontrolsource.h" #define GST_CAT_DEFAULT control_source_debug GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT); #define _do_init \ GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "gstcontrolsource", 0, \ "dynamic parameter control sources"); G_DEFINE_ABSTRACT_TYPE_WITH_CODE (GstControlSource, gst_control_source, GST_TYPE_OBJECT, _do_init); static GObject *gst_control_source_constructor (GType type, guint n_construct_params, GObjectConstructParam * construct_params); static void gst_control_source_class_init (GstControlSourceClass * klass) { GObjectClass *gobject_class = G_OBJECT_CLASS (klass); gobject_class->constructor = gst_control_source_constructor; } static void gst_control_source_init (GstControlSource * self) { self->get_value = NULL; self->get_value_array = NULL; } static GObject * gst_control_source_constructor (GType type, guint n_construct_params, GObjectConstructParam * construct_params) { GObject *self; self = G_OBJECT_CLASS (gst_control_source_parent_class)->constructor (type, n_construct_params, construct_params); gst_object_ref_sink (self); return self; } /** * gst_control_source_get_value: * @self: the #GstControlSource object * @timestamp: the time for which the value should be returned * @value: the value * * Gets the value for this #GstControlSource at a given timestamp. * * Returns: FALSE if the value couldn't be returned, TRUE otherwise. */ gboolean gst_control_source_get_value (GstControlSource * self, GstClockTime timestamp, gdouble * value) { g_return_val_if_fail (GST_IS_CONTROL_SOURCE (self), FALSE); if (G_LIKELY (self->get_value)) { return self->get_value (self, timestamp, value); } else { GST_ERROR ("Not bound to a specific property yet!"); return FALSE; } } /** * gst_control_source_get_value_array: * @self: the #GstControlSource object * @timestamp: the first timestamp * @interval: the time steps * @n_values: the number of values to fetch * @values: array to put control-values in * * Gets an array of values for for this #GstControlSource. Values that are * undefined contain NANs. * * Returns: %TRUE if the given array could be filled, %FALSE otherwise */ gboolean gst_control_source_get_value_array (GstControlSource * self, GstClockTime timestamp, GstClockTime interval, guint n_values, gdouble * values) { g_return_val_if_fail (GST_IS_CONTROL_SOURCE (self), FALSE); if (G_LIKELY (self->get_value_array)) { return self->get_value_array (self, timestamp, interval, n_values, values); } else { GST_ERROR ("Not bound to a specific property yet!"); return FALSE; } }