1 /*
2 * GStreamer AVTP Plugin
3 * Copyright (C) 2019 Intel Corporation
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
19 */
20
21 /**
22 * SECTION:element-avtpcrfsync
23 * @see_also: avtpcrfcheck
24 *
25 * Adjust the Presentation Time from AVTPDUs to align with the reference clock
26 * provided by the CRF stream. For detailed information see chapter 10 in
27 * https://standards.ieee.org/standard/1722-2016.html. A helpful aid for
28 * visualizing CRF and it's advantages can be found at
29 * http://grouper.ieee.org/groups/1722/contributions/2014/1722a-rsilfvast-Diagrams%20for%20Common%20Timing%20Grid%20and%20Presentation%20Time%20(for%20review%20and%20discussion).pdf
30 * (Look at page 1).
31 *
32 * <refsect2>
33 * <title>Example pipeline</title>
34 * |[
35 * gst-launch-1.0 audiotestsrc ! audioconvert ! avtpaafpay ! avtpcrfsync ! avtpsink
36 * ]| This example pipeline will adjust the timestamps for rawaudio payload.
37 * Refer to the avtpcrfcheck example to validate the adjusted timestamp.
38 * </refsect2>
39 */
40
41 #include <avtp.h>
42 #include <avtp_aaf.h>
43 #include <avtp_crf.h>
44 #include <avtp_cvf.h>
45 #include <glib.h>
46 #include <math.h>
47
48 #include "gstavtpcrfbase.h"
49 #include "gstavtpcrfsync.h"
50 #include "gstavtpcrfutil.h"
51
52 GST_DEBUG_CATEGORY_STATIC (avtpcrfsync_debug);
53 #define GST_CAT_DEFAULT (avtpcrfsync_debug)
54
55 #define gst_avtp_crf_sync_parent_class parent_class
56 G_DEFINE_TYPE (GstAvtpCrfSync, gst_avtp_crf_sync, GST_TYPE_AVTP_CRF_BASE);
57 GST_ELEMENT_REGISTER_DEFINE (avtpcrfsync, "avtpcrfsync", GST_RANK_NONE,
58 GST_TYPE_AVTP_CRF_SYNC);
59 static GstFlowReturn gst_avtp_crf_sync_transform_ip (GstBaseTransform * parent,
60 GstBuffer * buffer);
61
62 static void
gst_avtp_crf_sync_class_init(GstAvtpCrfSyncClass * klass)63 gst_avtp_crf_sync_class_init (GstAvtpCrfSyncClass * klass)
64 {
65 GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
66
67 gst_element_class_set_static_metadata (element_class,
68 "Clock Reference Format (CRF) Synchronizer",
69 "Filter/Network/AVTP",
70 "Synchronize Presentation Time from AVTPDUs so they are phase-locked with clock provided by CRF stream",
71 "Vedang Patel <vedang.patel@intel.com>");
72
73 GST_BASE_TRANSFORM_CLASS (klass)->transform_ip =
74 GST_DEBUG_FUNCPTR (gst_avtp_crf_sync_transform_ip);
75
76 GST_DEBUG_CATEGORY_INIT (avtpcrfsync_debug, "avtpcrfsync", 0,
77 "CRF Synchronizer");
78 }
79
80 static void
gst_avtp_crf_sync_init(GstAvtpCrfSync * avtpcrfsync)81 gst_avtp_crf_sync_init (GstAvtpCrfSync * avtpcrfsync)
82 {
83 /* Nothing to do here. */
84 }
85
86 static void
set_avtp_tstamp(GstAvtpCrfSync * avtpcrfsync,struct avtp_stream_pdu * pdu,GstClockTime tstamp)87 set_avtp_tstamp (GstAvtpCrfSync * avtpcrfsync, struct avtp_stream_pdu *pdu,
88 GstClockTime tstamp)
89 {
90 int res;
91 guint32 type;
92
93 res =
94 avtp_pdu_get ((struct avtp_common_pdu *) pdu, AVTP_FIELD_SUBTYPE, &type);
95 g_assert (res == 0);
96
97 switch (type) {
98 case AVTP_SUBTYPE_AAF:
99 res = avtp_aaf_pdu_set (pdu, AVTP_AAF_FIELD_TIMESTAMP, tstamp);
100 g_assert (res == 0);
101 break;
102 case AVTP_SUBTYPE_CVF:
103 res = avtp_cvf_pdu_set (pdu, AVTP_CVF_FIELD_TIMESTAMP, tstamp);
104 g_assert (res == 0);
105 break;
106 default:
107 GST_ERROR_OBJECT (avtpcrfsync, "type 0x%x not supported.\n", type);
108 break;
109 }
110 }
111
112 static void
set_avtp_mr_bit(GstAvtpCrfSync * avtpcrfsync,struct avtp_stream_pdu * pdu,guint64 mr)113 set_avtp_mr_bit (GstAvtpCrfSync * avtpcrfsync, struct avtp_stream_pdu *pdu,
114 guint64 mr)
115 {
116 int res;
117 guint32 type;
118
119 res =
120 avtp_pdu_get ((struct avtp_common_pdu *) pdu, AVTP_FIELD_SUBTYPE, &type);
121 g_assert (res == 0);
122
123 switch (type) {
124 case AVTP_SUBTYPE_AAF:
125 res = avtp_aaf_pdu_set (pdu, AVTP_AAF_FIELD_MR, mr);
126 g_assert (res == 0);
127 break;
128 case AVTP_SUBTYPE_CVF:
129 res = avtp_cvf_pdu_set (pdu, AVTP_CVF_FIELD_MR, mr);
130 g_assert (res == 0);
131 break;
132 default:
133 GST_ERROR_OBJECT (avtpcrfsync, "type 0x%x not supported.\n", type);
134 break;
135 }
136 }
137
138 static GstFlowReturn
gst_avtp_crf_sync_transform_ip(GstBaseTransform * parent,GstBuffer * buffer)139 gst_avtp_crf_sync_transform_ip (GstBaseTransform * parent, GstBuffer * buffer)
140 {
141 GstClockTime tstamp, h264_time = 0, adjusted_tstamp, adjusted_h264_time = 0;
142 GstAvtpCrfBase *avtpcrfbase = GST_AVTP_CRF_BASE (parent);
143 GstAvtpCrfSync *avtpcrfsync = GST_AVTP_CRF_SYNC (avtpcrfbase);
144 GstAvtpCrfThreadData *thread_data = &avtpcrfbase->thread_data;
145 GstClockTime current_ts = thread_data->current_ts;
146 gdouble avg_period = thread_data->average_period;
147 struct avtp_stream_pdu *pdu;
148 gboolean h264_packet;
149 GstMapInfo info;
150 gboolean res;
151
152 if (!avg_period || !current_ts) {
153 GST_WARNING_OBJECT (avtpcrfsync, "No CRF packet yet received!");
154 return GST_FLOW_OK;
155 }
156
157 res = gst_buffer_map (buffer, &info, GST_MAP_READWRITE);
158 if (!res) {
159 GST_ELEMENT_ERROR (avtpcrfsync, RESOURCE, OPEN_WRITE,
160 ("cannot access buffer"), (NULL));
161 return GST_FLOW_ERROR;
162 }
163
164 if (!buffer_size_valid (&info)) {
165 GST_DEBUG_OBJECT (avtpcrfsync, "Malformed AVTPDU, discarding it");
166 goto exit;
167 }
168
169 pdu = (struct avtp_stream_pdu *) info.data;
170
171 h264_packet = h264_tstamp_valid (pdu);
172
173 if (h264_packet) {
174 res = avtp_cvf_pdu_get (pdu, AVTP_CVF_FIELD_H264_TIMESTAMP, &h264_time);
175 g_assert (res == 0);
176
177 /*
178 * Extrapolate H264 tstamp to 64 bit and assume it's greater than CRF
179 * timestamp.
180 */
181 h264_time |= current_ts & 0xFFFFFFFF00000000;
182 if (h264_time < current_ts)
183 h264_time += (1ULL << 32);
184
185 /*
186 * float typecasted to guint64 truncates the decimal part. So, round() it
187 * before casting.
188 */
189 adjusted_h264_time =
190 (GstClockTime) roundl (current_ts + ceill (((gdouble) h264_time -
191 current_ts) / avg_period) * avg_period);
192 res =
193 avtp_cvf_pdu_set (pdu, AVTP_CVF_FIELD_H264_TIMESTAMP,
194 adjusted_h264_time);
195 g_assert (res == 0);
196
197 GST_LOG_OBJECT (avtpcrfsync,
198 "Adjust H264 timestamp in CVF packet. tstamp: %" G_GUINT64_FORMAT
199 " adjusted_tstamp: %" G_GUINT64_FORMAT,
200 h264_time & 0xFFFFFFFF, adjusted_h264_time & 0xFFFFFFFF);
201 }
202
203 tstamp = get_avtp_tstamp (avtpcrfbase, pdu);
204 if (tstamp == GST_CLOCK_TIME_NONE)
205 goto exit;
206
207 /*
208 * Extrapolate the 32-bit AVTP Timestamp to 64-bit and assume it's greater
209 * than the 64-bit CRF timestamp.
210 */
211 tstamp |= current_ts & 0xFFFFFFFF00000000;
212 if (tstamp < current_ts)
213 tstamp += (1ULL << 32);
214
215 /*
216 * float typecasted to guint64 truncates the decimal part. So, round() it
217 * before casting.
218 */
219 adjusted_tstamp =
220 (GstClockTime) roundl (current_ts + ceill ((tstamp -
221 current_ts) / avg_period) * avg_period);
222 set_avtp_tstamp (avtpcrfsync, pdu, adjusted_tstamp);
223 set_avtp_mr_bit (avtpcrfsync, pdu, thread_data->mr);
224 GST_LOG_OBJECT (avtpcrfsync,
225 "Adjust AVTP timestamp. tstamp: %" G_GUINT64_FORMAT
226 " Adjusted tstamp: %" G_GUINT64_FORMAT,
227 tstamp & 0xFFFFFFFF, adjusted_tstamp & 0xFFFFFFFF);
228
229 /*
230 * Since we adjusted the AVTP/H264 presentation times in the AVTPDU, we also
231 * need to adjust buffer times by the same amount so that the buffer is
232 * transmitted at the right time.
233 */
234 if (h264_packet) {
235 if (GST_BUFFER_DTS (buffer) != GST_CLOCK_TIME_NONE)
236 GST_BUFFER_DTS (buffer) += adjusted_tstamp - tstamp;
237 GST_BUFFER_PTS (buffer) += adjusted_h264_time - h264_time;
238 } else {
239 GST_BUFFER_PTS (buffer) += adjusted_tstamp - tstamp;
240 }
241
242 exit:
243 gst_buffer_unmap (buffer, &info);
244 return GST_FLOW_OK;
245 }
246