1 /* GStreamer plugin for forward error correction
2 * Copyright (C) 2017 Pexip
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.
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.
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
18 * Author: Mikhail Fludkov <misha@pexip.com>
22 * SECTION:element-rtpulpfecdec
23 * @short_description: Generic RTP Forward Error Correction (FEC) decoder
24 * @title: rtpulpfecdec
26 * Generic Forward Error Correction (FEC) decoder for Uneven Level
27 * Protection (ULP) as described in RFC 5109.
32 #include <gst/rtp/gstrtpbuffer.h>
33 #include <gst/rtp/gstrtp-enumtypes.h>
35 #include "rtpulpfeccommon.h"
36 #include "gstrtpulpfecdec.h"
38 static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
41 GST_STATIC_CAPS ("application/x-rtp")
44 static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
47 GST_STATIC_CAPS ("application/x-rtp")
60 #define DEFAULT_FEC_PT 0
62 static GParamSpec *klass_properties[N_PROPERTIES] = { NULL, };
64 GST_DEBUG_CATEGORY (gst_rtp_ulpfec_dec_debug);
65 #define GST_CAT_DEFAULT (gst_rtp_ulpfec_dec_debug)
67 G_DEFINE_TYPE (GstRtpUlpFecDec, gst_rtp_ulpfec_dec, GST_TYPE_ELEMENT);
69 #define RTP_FEC_MAP_INFO_NTH(dec, data) (&g_array_index (\
70 ((GstRtpUlpFecDec *)dec)->info_arr, \
72 GPOINTER_TO_UINT(data)))
75 _compare_fec_map_info (gconstpointer a, gconstpointer b, gpointer userdata)
78 gst_rtp_buffer_get_seq (&RTP_FEC_MAP_INFO_NTH (userdata, a)->rtp);
80 gst_rtp_buffer_get_seq (&RTP_FEC_MAP_INFO_NTH (userdata, b)->rtp);
81 return gst_rtp_buffer_compare_seqnum (bseq, aseq);
85 gst_rtp_ulpfec_dec_start (GstRtpUlpFecDec * self, GstBufferList * buflist,
86 guint8 fec_pt, guint16 lost_seq)
88 guint fec_packets = 0;
90 g_assert (NULL == self->info_media);
91 g_assert (0 == self->info_fec->len);
92 g_assert (0 == self->info_arr->len);
94 g_array_set_size (self->info_arr, gst_buffer_list_length (buflist));
97 i < gst_buffer_list_length (buflist) && !self->lost_packet_from_storage;
99 GstBuffer *buffer = gst_buffer_list_get (buflist, i);
100 RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self, i);
102 if (!rtp_ulpfec_map_info_map (gst_buffer_ref (buffer), info))
103 g_assert_not_reached ();
105 if (fec_pt == gst_rtp_buffer_get_payload_type (&info->rtp)) {
106 GST_DEBUG_RTP_PACKET (self, "rtp header (fec)", &info->rtp);
109 if (rtp_ulpfec_buffer_is_valid (&info->rtp)) {
110 GST_DEBUG_FEC_PACKET (self, &info->rtp);
111 g_ptr_array_add (self->info_fec, GUINT_TO_POINTER (i));
114 GST_LOG_RTP_PACKET (self, "rtp header (incoming)", &info->rtp);
116 if (lost_seq == gst_rtp_buffer_get_seq (&info->rtp)) {
117 GST_DEBUG_OBJECT (self, "Received lost packet from from the storage");
118 g_list_free (self->info_media);
119 self->info_media = NULL;
120 self->lost_packet_from_storage = TRUE;
123 g_list_insert_sorted_with_data (self->info_media,
124 GUINT_TO_POINTER (i), _compare_fec_map_info, self);
127 if (!self->lost_packet_from_storage) {
128 self->fec_packets_received += fec_packets;
129 self->fec_packets_rejected += fec_packets - self->info_fec->len;
134 gst_rtp_ulpfec_dec_stop (GstRtpUlpFecDec * self)
136 g_array_set_size (self->info_arr, 0);
137 g_ptr_array_set_size (self->info_fec, 0);
138 g_list_free (self->info_media);
139 self->info_media = NULL;
140 self->lost_packet_from_storage = FALSE;
141 self->lost_packet_returned = FALSE;
145 gst_rtp_ulpfec_dec_get_media_buffers_mask (GstRtpUlpFecDec * self,
146 guint16 fec_seq_base)
149 for (GList * it = self->info_media; it; it = it->next) {
150 RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self, it->data);
152 rtp_ulpfec_packet_mask_from_seqnum (gst_rtp_buffer_get_seq (&info->rtp),
159 gst_rtp_ulpfec_dec_is_recovered_pt_valid (GstRtpUlpFecDec * self, gint media_pt,
162 if (media_pt == recovered_pt)
165 for (GList * it = self->info_media; it; it = it->next) {
166 RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self, it->data);
167 if (gst_rtp_buffer_get_payload_type (&info->rtp) == recovered_pt)
174 gst_rtp_ulpfec_dec_recover_from_fec (GstRtpUlpFecDec * self,
175 RtpUlpFecMapInfo * info_fec, guint32 ssrc, gint media_pt, guint16 seq,
178 guint64 fec_mask = rtp_ulpfec_buffer_get_mask (&info_fec->rtp);
179 gboolean fec_mask_long = rtp_ulpfec_buffer_get_fechdr (&info_fec->rtp)->L;
180 guint16 fec_seq_base = rtp_ulpfec_buffer_get_seq_base (&info_fec->rtp);
183 g_array_set_size (self->scratch_buf, 0);
184 rtp_buffer_to_ulpfec_bitstring (&info_fec->rtp, self->scratch_buf, TRUE,
187 for (GList * it = self->info_media; it; it = it->next) {
188 RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self, it->data);
189 guint64 packet_mask =
190 rtp_ulpfec_packet_mask_from_seqnum (gst_rtp_buffer_get_seq (&info->rtp),
193 if (fec_mask & packet_mask) {
194 fec_mask ^= packet_mask;
195 rtp_buffer_to_ulpfec_bitstring (&info->rtp, self->scratch_buf, FALSE,
201 rtp_ulpfec_bitstring_to_media_rtp_buffer (self->scratch_buf,
202 fec_mask_long, ssrc, seq);
204 /* We are about to put recovered packet back in self->info_media to be able
205 * to reuse it later for recovery of other packets
207 gint i = self->info_arr->len;
208 RtpUlpFecMapInfo *info;
211 g_array_set_size (self->info_arr, self->info_arr->len + 1);
212 info = RTP_FEC_MAP_INFO_NTH (self, i);
214 if (!rtp_ulpfec_map_info_map (gst_buffer_ref (ret), info)) {
215 GST_WARNING_OBJECT (self, "Invalid recovered packet");
216 goto recovered_packet_invalid;
219 recovered_pt = gst_rtp_buffer_get_payload_type (&info->rtp);
220 if (!gst_rtp_ulpfec_dec_is_recovered_pt_valid (self, media_pt,
222 GST_WARNING_OBJECT (self,
223 "Recovered packet has unexpected payload type (%u)", recovered_pt);
224 goto recovered_packet_invalid;
227 GST_DEBUG_RTP_PACKET (self, "rtp header (recovered)", &info->rtp);
229 g_list_insert_sorted_with_data (self->info_media, GUINT_TO_POINTER (i),
230 _compare_fec_map_info, self);
231 *dst_pt = recovered_pt;
235 recovered_packet_invalid:
236 g_array_set_size (self->info_arr, self->info_arr->len - 1);
237 gst_buffer_unref (ret);
242 gst_rtp_ulpfec_dec_recover_from_storage (GstRtpUlpFecDec * self,
243 guint8 * dst_pt, guint16 * dst_seq)
245 RtpUlpFecMapInfo *info;
247 if (self->lost_packet_returned)
250 g_assert (g_list_length (self->info_media) == 1);
252 info = RTP_FEC_MAP_INFO_NTH (self, self->info_media->data);
253 *dst_seq = gst_rtp_buffer_get_seq (&info->rtp);
254 *dst_pt = gst_rtp_buffer_get_payload_type (&info->rtp);
255 self->lost_packet_returned = TRUE;
256 GST_DEBUG_RTP_PACKET (self, "rtp header (recovered)", &info->rtp);
257 return gst_buffer_ref (info->rtp.buffer);
261 gst_rtp_ulpfec_dec_recover (GstRtpUlpFecDec * self, guint32 ssrc, gint media_pt,
262 guint8 * dst_pt, guint16 * dst_seq)
264 guint64 media_mask = 0;
265 gint media_mask_seq_base = -1;
267 if (self->lost_packet_from_storage)
268 return gst_rtp_ulpfec_dec_recover_from_storage (self, dst_pt, dst_seq);
270 /* Looking for a FEC packet which can be used for recovery */
271 for (gsize i = 0; i < self->info_fec->len; ++i) {
272 RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self,
273 g_ptr_array_index (self->info_fec, i));
274 guint16 seq_base = rtp_ulpfec_buffer_get_seq_base (&info->rtp);
275 guint64 fec_mask = rtp_ulpfec_buffer_get_mask (&info->rtp);
276 guint64 missing_packets_mask;
278 if (media_mask_seq_base != (gint) seq_base) {
279 media_mask_seq_base = seq_base;
280 media_mask = gst_rtp_ulpfec_dec_get_media_buffers_mask (self, seq_base);
283 /* media_mask has 1s if packet exist.
284 * fec_mask is the mask of protected packets
285 * The statement below excludes existing packets from the protected. So
286 * we are left with 1s only for missing packets which can be recovered
287 * by this FEC packet. */
288 missing_packets_mask = fec_mask & (~media_mask);
290 /* Do we have any 1s? Checking if current FEC packet can be used for recovery */
291 if (0 != missing_packets_mask) {
292 guint trailing_zeros = __builtin_ctzll (missing_packets_mask);
294 /* Is it the only 1 in the mask? Checking if we lacking single packet in
295 * that case FEC packet can be used for recovery */
296 if (missing_packets_mask == (1ULL << trailing_zeros)) {
300 seq_base + (RTP_ULPFEC_SEQ_BASE_OFFSET_MAX (TRUE) - trailing_zeros);
302 gst_rtp_ulpfec_dec_recover_from_fec (self, info, ssrc, media_pt,
313 gst_rtp_ulpfec_dec_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
315 GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (parent);
317 if (G_LIKELY (GST_FLOW_OK == self->chain_return_val)) {
318 if (G_UNLIKELY (self->unset_discont_flag)) {
319 self->unset_discont_flag = FALSE;
320 buf = gst_buffer_make_writable (buf);
321 GST_BUFFER_FLAG_UNSET (buf, GST_BUFFER_FLAG_DISCONT);
323 return gst_pad_push (self->srcpad, buf);
326 gst_buffer_unref (buf);
327 return self->chain_return_val;
331 gst_rtp_ulpfec_dec_handle_packet_loss (GstRtpUlpFecDec * self, guint16 seqnum,
332 GstClockTime timestamp, GstClockTime duration)
334 gint caps_pt = self->have_caps_pt ? self->caps_pt : -1;
336 GstBufferList *buflist =
337 rtp_storage_get_packets_for_recovery (self->storage, self->fec_pt,
338 self->caps_ssrc, seqnum);
341 GstBuffer *recovered_buffer = NULL;
342 guint16 recovered_seq = 0;
343 guint8 recovered_pt = 0;
345 gst_rtp_ulpfec_dec_start (self, buflist, self->fec_pt, seqnum);
347 while (NULL != (recovered_buffer =
348 gst_rtp_ulpfec_dec_recover (self, self->caps_ssrc, caps_pt,
349 &recovered_pt, &recovered_seq))) {
350 if (seqnum == recovered_seq) {
351 recovered_buffer = gst_buffer_make_writable (recovered_buffer);
352 GST_BUFFER_PTS (recovered_buffer) = timestamp;
353 /* GST_BUFFER_DURATION (recovered_buffer) = duration;
354 * JB does not set the duration, so we will not too */
356 if (!self->lost_packet_from_storage)
357 rtp_storage_put_recovered_packet (self->storage,
358 gst_buffer_ref (recovered_buffer), recovered_pt, self->caps_ssrc,
361 GST_DEBUG_OBJECT (self,
362 "Pushing recovered packet ssrc=0x%08x seq=%u %" GST_PTR_FORMAT,
363 self->caps_ssrc, seqnum, recovered_buffer);
366 self->unset_discont_flag = TRUE;
367 self->chain_return_val = gst_pad_push (self->srcpad, recovered_buffer);
371 rtp_storage_put_recovered_packet (self->storage,
372 recovered_buffer, recovered_pt, self->caps_ssrc, recovered_seq);
375 gst_rtp_ulpfec_dec_stop (self);
376 gst_buffer_list_unref (buflist);
379 GST_DEBUG_OBJECT (self, "Packet lost ssrc=0x%08x seq=%u", self->caps_ssrc,
386 gst_rtp_ulpfec_dec_handle_sink_event (GstPad * pad, GstObject * parent,
389 GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (parent);
390 gboolean forward = TRUE;
392 GST_LOG_OBJECT (self, "Received event %" GST_PTR_FORMAT, event);
394 if (GST_FLOW_OK == self->chain_return_val &&
395 GST_EVENT_CUSTOM_DOWNSTREAM == GST_EVENT_TYPE (event) &&
396 gst_event_has_name (event, "GstRTPPacketLost")) {
398 GstClockTime timestamp, duration;
400 g_assert (self->have_caps_ssrc);
401 g_assert (self->storage);
403 if (!gst_structure_get (gst_event_get_structure (event),
404 "seqnum", G_TYPE_UINT, &seqnum,
405 "timestamp", G_TYPE_UINT64, ×tamp,
406 "duration", G_TYPE_UINT64, &duration, NULL))
407 g_assert_not_reached ();
410 gst_rtp_ulpfec_dec_handle_packet_loss (self, seqnum, timestamp,
413 ++self->packets_unrecovered;
415 ++self->packets_recovered;
416 GST_DEBUG_OBJECT (self, "Unrecovered / Recovered: %lu / %lu",
417 self->packets_unrecovered, self->packets_recovered);
418 } else if (GST_EVENT_CAPS == GST_EVENT_TYPE (event)) {
420 gboolean have_caps_pt = FALSE;
421 gboolean have_caps_ssrc = FALSE;
425 gst_event_parse_caps (event, &caps);
427 gst_structure_get_uint (gst_caps_get_structure (caps, 0), "ssrc",
430 gst_structure_get_int (gst_caps_get_structure (caps, 0), "payload",
433 if (self->have_caps_ssrc != have_caps_ssrc || self->caps_ssrc != caps_ssrc)
434 GST_DEBUG_OBJECT (self, "SSRC changed %u, 0x%08x -> %u, 0x%08x",
435 self->have_caps_ssrc, self->caps_ssrc, have_caps_ssrc, caps_ssrc);
436 if (self->have_caps_pt != have_caps_pt || self->caps_pt != caps_pt)
437 GST_DEBUG_OBJECT (self, "PT changed %u, %u -> %u, %u",
438 self->have_caps_pt, self->caps_pt, have_caps_pt, caps_pt);
440 self->have_caps_ssrc = have_caps_ssrc;
441 self->have_caps_pt = have_caps_pt;
442 self->caps_ssrc = caps_ssrc;
443 self->caps_pt = caps_pt;
447 return gst_pad_push_event (self->srcpad, event);
448 gst_event_unref (event);
453 gst_rtp_ulpfec_dec_init (GstRtpUlpFecDec * self)
455 self->srcpad = gst_pad_new_from_static_template (&srctemplate, "src");
456 self->sinkpad = gst_pad_new_from_static_template (&sinktemplate, "sink");
457 GST_PAD_SET_PROXY_CAPS (self->sinkpad);
458 GST_PAD_SET_PROXY_ALLOCATION (self->sinkpad);
459 gst_pad_set_chain_function (self->sinkpad,
460 GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_chain));
461 gst_pad_set_event_function (self->sinkpad,
462 GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_handle_sink_event));
464 gst_element_add_pad (GST_ELEMENT (self), self->srcpad);
465 gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);
467 self->fec_pt = DEFAULT_FEC_PT;
469 self->chain_return_val = GST_FLOW_OK;
470 self->have_caps_ssrc = FALSE;
472 self->info_fec = g_ptr_array_new ();
473 self->info_arr = g_array_new (FALSE, TRUE, sizeof (RtpUlpFecMapInfo));
474 g_array_set_clear_func (self->info_arr,
475 (GDestroyNotify) rtp_ulpfec_map_info_unmap);
476 self->scratch_buf = g_array_new (FALSE, TRUE, sizeof (guint8));
480 gst_rtp_ulpfec_dec_dispose (GObject * obj)
482 GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (obj);
484 GST_INFO_OBJECT (self,
486 " packets_recovered=%" G_GSIZE_FORMAT
487 " packets_unrecovered=%" G_GSIZE_FORMAT,
488 self->caps_ssrc, self->caps_pt,
489 self->packets_recovered, self->packets_unrecovered);
492 g_object_unref (self->storage);
494 g_assert (NULL == self->info_media);
495 g_assert (0 == self->info_fec->len);
496 g_assert (0 == self->info_arr->len);
498 if (self->fec_packets_received) {
499 GST_INFO_OBJECT (self,
500 " fec_packets_received=%" G_GSIZE_FORMAT
501 " fec_packets_rejected=%" G_GSIZE_FORMAT
502 " packets_rejected=%" G_GSIZE_FORMAT,
503 self->fec_packets_received,
504 self->fec_packets_rejected, self->packets_rejected);
507 g_ptr_array_free (self->info_fec, TRUE);
508 g_array_free (self->info_arr, TRUE);
509 g_array_free (self->scratch_buf, TRUE);
511 G_OBJECT_CLASS (gst_rtp_ulpfec_dec_parent_class)->dispose (obj);
515 gst_rtp_ulpfec_dec_set_property (GObject * object, guint prop_id,
516 const GValue * value, GParamSpec * pspec)
518 GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (object);
522 self->fec_pt = g_value_get_uint (value);
526 g_object_unref (self->storage);
527 self->storage = g_value_get_object (value);
529 g_object_ref (self->storage);
532 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
538 gst_rtp_ulpfec_dec_get_property (GObject * object, guint prop_id,
539 GValue * value, GParamSpec * pspec)
541 GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (object);
545 g_value_set_uint (value, self->fec_pt);
548 g_value_set_object (value, self->storage);
551 g_value_set_uint (value, (guint) self->packets_recovered);
553 case PROP_UNRECOVERED:
554 g_value_set_uint (value, (guint) self->packets_unrecovered);
557 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
563 gst_rtp_ulpfec_dec_class_init (GstRtpUlpFecDecClass * klass)
565 GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
566 GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
568 GST_DEBUG_CATEGORY_INIT (gst_rtp_ulpfec_dec_debug,
569 "rtpulpfecdec", 0, "RTP FEC Decoder");
571 gst_element_class_add_pad_template (element_class,
572 gst_static_pad_template_get (&srctemplate));
573 gst_element_class_add_pad_template (element_class,
574 gst_static_pad_template_get (&sinktemplate));
576 gst_element_class_set_static_metadata (element_class,
578 "Codec/Depayloader/Network/RTP",
579 "Decodes RTP FEC (RFC5109)", "Mikhail Fludkov <misha@pexip.com>");
581 gobject_class->set_property =
582 GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_set_property);
583 gobject_class->get_property =
584 GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_get_property);
585 gobject_class->dispose = GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_dispose);
587 klass_properties[PROP_PT] = g_param_spec_uint ("pt", "pt",
588 "FEC packets payload type", 0, 127,
589 DEFAULT_FEC_PT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
590 klass_properties[PROP_STORAGE] =
591 g_param_spec_object ("storage", "RTP storage", "RTP storage",
592 G_TYPE_OBJECT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
593 klass_properties[PROP_RECOVERED] =
594 g_param_spec_uint ("recovered", "recovered",
595 "The number of recovered packets", 0, G_MAXUINT, 0,
596 G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
597 klass_properties[PROP_UNRECOVERED] =
598 g_param_spec_uint ("unrecovered", "unrecovered",
599 "The number of unrecovered packets", 0, G_MAXUINT, 0,
600 G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
602 g_object_class_install_properties (gobject_class, N_PROPERTIES,