1 /* GStreamer plugin for forward error correction
2 * Copyright (C) 2017 Pexip
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 *
18 * Author: Mikhail Fludkov <misha@pexip.com>
19 */
20
21 /**
22 * SECTION:element-rtpstorage
23 * @short_description: RTP storage for forward error correction (FEC) in rtpbin
24 * @title: rtpstorage
25 *
26 * Helper element for storing packets to aid later packet recovery from packet
27 * loss using RED/FEC (Forward Error Correction).
28 *
29 * The purpose of this element is to store a moving window of packets which
30 * downstream elements such as #GstRtpUlpFecDec can request in order to perform
31 * recovery of lost packets upon receiving custom GstRtpPacketLost events,
32 * usually from #GstRtpJitterBuffer.
33 *
34 * As such, when building a pipeline manually, it should have the form:
35 *
36 * ```
37 * rtpstorage ! rtpjitterbuffer ! rtpulpfecdec
38 * ```
39 *
40 * where rtpulpfecdec get passed a reference to the object pointed to by
41 * the #GstRtpStorage:internal-storage property.
42 *
43 * The #GstRtpStorage:size-time property should be configured with a value
44 * equal to the #GstRtpJitterBuffer latency, plus some tolerance, in the order
45 * of milliseconds, for example in the example found at
46 * <https://github.com/sdroege/gstreamer-rs/blob/master/examples/src/bin/rtpfecclient.rs>,
47 * `size-time` is configured as 200 + 50 milliseconds (latency + tolerance).
48 *
49 * When using #GstRtpBin, a storage element is created automatically, and
50 * can be configured upon receiving the #GstRtpBin::new-storage signal.
51 *
52 * See also: #GstRtpBin, #GstRtpUlpFecDec
53 * Since: 1.14
54 */
55
56 #include "gstrtpelements.h"
57 #include "gstrtpstorage.h"
58
59 static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
60 GST_PAD_SINK,
61 GST_PAD_ALWAYS,
62 GST_STATIC_CAPS ("application/x-rtp")
63 );
64
65 static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
66 GST_PAD_SRC,
67 GST_PAD_ALWAYS,
68 GST_STATIC_CAPS ("application/x-rtp")
69 );
70
71 enum
72 {
73 PROP_0,
74 PROP_SIZE_TIME,
75 PROP_INTERNAL_STORAGE,
76 N_PROPERTIES
77 };
78
79 static GParamSpec *klass_properties[N_PROPERTIES] = { NULL, };
80
81 #define DEFAULT_SIZE_TIME (0)
82
83 GST_DEBUG_CATEGORY (gst_rtp_storage_debug);
84 #define GST_CAT_DEFAULT (gst_rtp_storage_debug)
85
86 G_DEFINE_TYPE (GstRtpStorage, gst_rtp_storage, GST_TYPE_ELEMENT);
87 GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (rtpstorage, "rtpstorage", GST_RANK_NONE,
88 GST_TYPE_RTP_STORAGE, rtp_element_init (plugin));
89
90 static GstFlowReturn
gst_rtp_storage_chain(GstPad * pad,GstObject * parent,GstBuffer * buf)91 gst_rtp_storage_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
92 {
93 GstRtpStorage *self = GST_RTP_STORAGE (parent);;
94
95 if (rtp_storage_append_buffer (self->storage, buf))
96 return gst_pad_push (self->srcpad, buf);
97 return GST_FLOW_OK;
98 }
99
100 static void
gst_rtp_storage_set_property(GObject * object,guint prop_id,const GValue * value,GParamSpec * pspec)101 gst_rtp_storage_set_property (GObject * object, guint prop_id,
102 const GValue * value, GParamSpec * pspec)
103 {
104 GstRtpStorage *self = GST_RTP_STORAGE (object);
105
106 switch (prop_id) {
107 case PROP_SIZE_TIME:
108 GST_DEBUG_OBJECT (self, "RTP storage size set to %" GST_TIME_FORMAT,
109 GST_TIME_ARGS (g_value_get_uint64 (value)));
110 rtp_storage_set_size (self->storage, g_value_get_uint64 (value));
111 break;
112 default:
113 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
114 break;
115 }
116 }
117
118 static void
gst_rtp_storage_get_property(GObject * object,guint prop_id,GValue * value,GParamSpec * pspec)119 gst_rtp_storage_get_property (GObject * object, guint prop_id,
120 GValue * value, GParamSpec * pspec)
121 {
122 GstRtpStorage *self = GST_RTP_STORAGE (object);
123 switch (prop_id) {
124 case PROP_SIZE_TIME:
125 g_value_set_uint64 (value, rtp_storage_get_size (self->storage));
126 break;
127 case PROP_INTERNAL_STORAGE:
128 {
129 g_value_set_object (value, self->storage);
130 break;
131 }
132 default:
133 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
134 break;
135 }
136 }
137
138 static gboolean
gst_rtp_storage_src_query(GstPad * pad,GstObject * parent,GstQuery * query)139 gst_rtp_storage_src_query (GstPad * pad, GstObject * parent, GstQuery * query)
140 {
141 GstRtpStorage *self = GST_RTP_STORAGE (parent);
142
143 if (GST_QUERY_TYPE (query) == GST_QUERY_CUSTOM) {
144 GstStructure *s = gst_query_writable_structure (query);
145
146 if (gst_structure_has_name (s, "GstRtpStorage")) {
147 gst_structure_set (s, "storage", G_TYPE_OBJECT, self->storage, NULL);
148 return TRUE;
149 }
150 }
151
152 return gst_pad_query_default (pad, parent, query);
153 }
154
155 static void
gst_rtp_storage_init(GstRtpStorage * self)156 gst_rtp_storage_init (GstRtpStorage * self)
157 {
158 self->srcpad = gst_pad_new_from_static_template (&srctemplate, "src");
159 self->sinkpad = gst_pad_new_from_static_template (&sinktemplate, "sink");
160 GST_PAD_SET_PROXY_CAPS (self->sinkpad);
161 GST_PAD_SET_PROXY_ALLOCATION (self->sinkpad);
162 gst_pad_set_chain_function (self->sinkpad, gst_rtp_storage_chain);
163
164 gst_pad_set_query_function (self->srcpad, gst_rtp_storage_src_query);
165
166 gst_element_add_pad (GST_ELEMENT (self), self->srcpad);
167 gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);
168
169 self->storage = rtp_storage_new ();
170 }
171
172 static void
gst_rtp_storage_dispose(GObject * obj)173 gst_rtp_storage_dispose (GObject * obj)
174 {
175 GstRtpStorage *self = GST_RTP_STORAGE (obj);
176 g_object_unref (self->storage);
177 G_OBJECT_CLASS (gst_rtp_storage_parent_class)->dispose (obj);
178 }
179
180 static void
gst_rtp_storage_class_init(GstRtpStorageClass * klass)181 gst_rtp_storage_class_init (GstRtpStorageClass * klass)
182 {
183 GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
184 GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
185
186 GST_DEBUG_CATEGORY_INIT (gst_rtp_storage_debug,
187 "rtpstorage", 0, "RTP Storage");
188 GST_DEBUG_REGISTER_FUNCPTR (gst_rtp_storage_chain);
189
190 gst_element_class_add_pad_template (element_class,
191 gst_static_pad_template_get (&srctemplate));
192 gst_element_class_add_pad_template (element_class,
193 gst_static_pad_template_get (&sinktemplate));
194
195 gst_element_class_set_static_metadata (element_class,
196 "RTP storage",
197 "Analyzer/RTP",
198 "Helper element for various purposes "
199 "(ex. recovering from packet loss using RED/FEC). "
200 "Saves given number of RTP packets. "
201 "Should be instantiated before jitterbuffer",
202 "Mikhail Fludkov <misha@pexip.com>");
203
204 gobject_class->set_property = gst_rtp_storage_set_property;
205 gobject_class->get_property = gst_rtp_storage_get_property;
206 gobject_class->dispose = gst_rtp_storage_dispose;
207
208 klass_properties[PROP_SIZE_TIME] =
209 g_param_spec_uint64 ("size-time", "Storage size (in ns)",
210 "The amount of data to keep in the storage (in ns, 0-disable)", 0,
211 G_MAXUINT64, DEFAULT_SIZE_TIME,
212 G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS);
213
214 klass_properties[PROP_INTERNAL_STORAGE] =
215 g_param_spec_object ("internal-storage", "Internal storage",
216 "Internal RtpStorage object", G_TYPE_OBJECT,
217 G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
218
219 g_object_class_install_properties (gobject_class, N_PROPERTIES,
220 klass_properties);
221 }
222