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 "gstrtpstorage.h"
57
58 static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
59 GST_PAD_SINK,
60 GST_PAD_ALWAYS,
61 GST_STATIC_CAPS ("application/x-rtp")
62 );
63
64 static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
65 GST_PAD_SRC,
66 GST_PAD_ALWAYS,
67 GST_STATIC_CAPS ("application/x-rtp")
68 );
69
70 enum
71 {
72 PROP_0,
73 PROP_SIZE_TIME,
74 PROP_INTERNAL_STORAGE,
75 N_PROPERTIES
76 };
77
78 static GParamSpec *klass_properties[N_PROPERTIES] = { NULL, };
79
80 #define DEFAULT_SIZE_TIME (0)
81
82 GST_DEBUG_CATEGORY (gst_rtp_storage_debug);
83 #define GST_CAT_DEFAULT (gst_rtp_storage_debug)
84
85 G_DEFINE_TYPE (GstRtpStorage, gst_rtp_storage, GST_TYPE_ELEMENT);
86
87 static GstFlowReturn
gst_rtp_storage_chain(GstPad * pad,GstObject * parent,GstBuffer * buf)88 gst_rtp_storage_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
89 {
90 GstRtpStorage *self = GST_RTP_STORAGE (parent);;
91
92 if (rtp_storage_append_buffer (self->storage, buf))
93 return gst_pad_push (self->srcpad, buf);
94 return GST_FLOW_OK;
95 }
96
97 static void
gst_rtp_storage_set_property(GObject * object,guint prop_id,const GValue * value,GParamSpec * pspec)98 gst_rtp_storage_set_property (GObject * object, guint prop_id,
99 const GValue * value, GParamSpec * pspec)
100 {
101 GstRtpStorage *self = GST_RTP_STORAGE (object);
102
103 switch (prop_id) {
104 case PROP_SIZE_TIME:
105 GST_DEBUG_OBJECT (self, "RTP storage size set to %" GST_TIME_FORMAT,
106 GST_TIME_ARGS (g_value_get_uint64 (value)));
107 rtp_storage_set_size (self->storage, g_value_get_uint64 (value));
108 break;
109 default:
110 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
111 break;
112 }
113 }
114
115 static void
gst_rtp_storage_get_property(GObject * object,guint prop_id,GValue * value,GParamSpec * pspec)116 gst_rtp_storage_get_property (GObject * object, guint prop_id,
117 GValue * value, GParamSpec * pspec)
118 {
119 GstRtpStorage *self = GST_RTP_STORAGE (object);
120 switch (prop_id) {
121 case PROP_SIZE_TIME:
122 g_value_set_uint64 (value, rtp_storage_get_size (self->storage));
123 break;
124 case PROP_INTERNAL_STORAGE:
125 {
126 g_value_set_object (value, self->storage);
127 break;
128 }
129 default:
130 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
131 break;
132 }
133 }
134
135 static gboolean
gst_rtp_storage_src_query(GstPad * pad,GstObject * parent,GstQuery * query)136 gst_rtp_storage_src_query (GstPad * pad, GstObject * parent, GstQuery * query)
137 {
138 GstRtpStorage *self = GST_RTP_STORAGE (parent);
139
140 if (GST_QUERY_TYPE (query) == GST_QUERY_CUSTOM) {
141 GstStructure *s = gst_query_writable_structure (query);
142
143 if (gst_structure_has_name (s, "GstRtpStorage")) {
144 gst_structure_set (s, "storage", G_TYPE_OBJECT, self->storage, NULL);
145 return TRUE;
146 }
147 }
148
149 return gst_pad_query_default (pad, parent, query);
150 }
151
152 static void
gst_rtp_storage_init(GstRtpStorage * self)153 gst_rtp_storage_init (GstRtpStorage * self)
154 {
155 self->srcpad = gst_pad_new_from_static_template (&srctemplate, "src");
156 self->sinkpad = gst_pad_new_from_static_template (&sinktemplate, "sink");
157 GST_PAD_SET_PROXY_CAPS (self->sinkpad);
158 GST_PAD_SET_PROXY_ALLOCATION (self->sinkpad);
159 gst_pad_set_chain_function (self->sinkpad, gst_rtp_storage_chain);
160
161 gst_pad_set_query_function (self->srcpad, gst_rtp_storage_src_query);
162
163 gst_element_add_pad (GST_ELEMENT (self), self->srcpad);
164 gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);
165
166 self->storage = rtp_storage_new ();
167 }
168
169 static void
gst_rtp_storage_dispose(GObject * obj)170 gst_rtp_storage_dispose (GObject * obj)
171 {
172 GstRtpStorage *self = GST_RTP_STORAGE (obj);
173 g_object_unref (self->storage);
174 G_OBJECT_CLASS (gst_rtp_storage_parent_class)->dispose (obj);
175 }
176
177 static void
gst_rtp_storage_class_init(GstRtpStorageClass * klass)178 gst_rtp_storage_class_init (GstRtpStorageClass * klass)
179 {
180 GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
181 GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
182
183 GST_DEBUG_CATEGORY_INIT (gst_rtp_storage_debug,
184 "rtpstorage", 0, "RTP Storage");
185 GST_DEBUG_REGISTER_FUNCPTR (gst_rtp_storage_chain);
186
187 gst_element_class_add_pad_template (element_class,
188 gst_static_pad_template_get (&srctemplate));
189 gst_element_class_add_pad_template (element_class,
190 gst_static_pad_template_get (&sinktemplate));
191
192 gst_element_class_set_static_metadata (element_class,
193 "RTP storage",
194 "Analyzer/RTP",
195 "Helper element for various purposes "
196 "(ex. recovering from packet loss using RED/FEC). "
197 "Saves given number of RTP packets. "
198 "Should be instantiated before jitterbuffer",
199 "Mikhail Fludkov <misha@pexip.com>");
200
201 gobject_class->set_property = gst_rtp_storage_set_property;
202 gobject_class->get_property = gst_rtp_storage_get_property;
203 gobject_class->dispose = gst_rtp_storage_dispose;
204
205 klass_properties[PROP_SIZE_TIME] =
206 g_param_spec_uint64 ("size-time", "Storage size (in ns)",
207 "The amount of data to keep in the storage (in ns, 0-disable)", 0,
208 G_MAXUINT64, DEFAULT_SIZE_TIME,
209 G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS);
210
211 klass_properties[PROP_INTERNAL_STORAGE] =
212 g_param_spec_object ("internal-storage", "Internal storage",
213 "Internal RtpStorage object", G_TYPE_OBJECT,
214 G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
215
216 g_object_class_install_properties (gobject_class, N_PROPERTIES,
217 klass_properties);
218 }
219