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