1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
/* 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., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, 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 to get timestamp-value pairs. A control source essentially is a
* function over time, returning float values between 0.0 and 1.0.
*
* A #GstControlSource is used by first getting an instance of a specific
* control-source, creating a binding for the control-source to the target property
* of the element and then adding the binding to the element. The binding will
* convert the data types and value range to fit to the bound property.
*
* For implementing a new #GstControlSource one has to implement
* #GstControlSourceGetValue and #GstControlSourceGetValueArray functions.
* These are then used by gst_control_source_get_value() and
* 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 length=n_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;
}
}
|
