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Limit to the queue size in case there is no arrival time or in case there is a huge flood of packets.
277 lines
8 KiB
C
277 lines
8 KiB
C
/* GStreamer plugin for forward error correction
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* Copyright (C) 2017 Pexip
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Author: Mikhail Fludkov <misha@pexip.com>
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*/
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#include "rtpstoragestream.h"
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#define GST_CAT_DEFAULT (gst_rtp_storage_debug)
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static RtpStorageItem *
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rtp_storage_item_new (GstBuffer * buffer, guint8 pt, guint16 seq)
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{
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RtpStorageItem *ret = g_slice_new0 (RtpStorageItem);
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ret->buffer = buffer;
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ret->pt = pt;
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ret->seq = seq;
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return ret;
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}
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static void
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rtp_storage_item_free (RtpStorageItem * item)
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{
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g_assert (item->buffer != NULL);
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gst_buffer_unref (item->buffer);
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g_slice_free (RtpStorageItem, item);
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}
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static gint
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rtp_storage_item_compare (gconstpointer a, gconstpointer b, gpointer userdata)
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{
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gint seq_diff = gst_rtp_buffer_compare_seqnum (
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((RtpStorageItem const *) a)->seq, ((RtpStorageItem const *) b)->seq);
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if (seq_diff >= 0)
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return 0;
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return 1;
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}
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static void
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rtp_storage_stream_resize (RtpStorageStream * stream, GstClockTime size_time)
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{
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GList *it;
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guint i, too_old_buffers_num = 0;
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g_assert (GST_CLOCK_TIME_IS_VALID (stream->max_arrival_time));
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g_assert (GST_CLOCK_TIME_IS_VALID (size_time));
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g_assert_cmpint (size_time, >, 0);
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/* Iterating from oldest sequence numbers to newest */
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for (i = 0, it = stream->queue.tail; it; it = it->prev, ++i) {
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RtpStorageItem *item = it->data;
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GstClockTime arrival_time = GST_BUFFER_DTS_OR_PTS (item->buffer);
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if (GST_CLOCK_TIME_IS_VALID (arrival_time)) {
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if (stream->max_arrival_time - arrival_time > size_time) {
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too_old_buffers_num = i + 1;
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} else
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break;
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}
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}
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for (i = 0; i < too_old_buffers_num; ++i) {
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RtpStorageItem *item = g_queue_pop_tail (&stream->queue);
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GST_TRACE ("Removing %u/%u buffers, pt=%d seq=%d for ssrc=%08x",
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i, too_old_buffers_num, item->pt, item->seq, stream->ssrc);
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rtp_storage_item_free (item);
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}
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}
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/* This algorithm corresponds to rtp_jitter_buffer_get_seqnum_diff(),
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* we want to keep the same number of packets in the worse case.
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*/
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static guint16
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rtp_storage_stream_get_seqnum_diff (RtpStorageStream * stream)
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{
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guint32 high_seqnum, low_seqnum;
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RtpStorageItem *high_item, *low_item;
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guint16 result;
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high_item = (RtpStorageItem *) g_queue_peek_head (&stream->queue);
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low_item = (RtpStorageItem *) g_queue_peek_tail (&stream->queue);
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if (!high_item || !low_item || high_item == low_item)
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return 0;
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high_seqnum = high_item->seq;
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low_seqnum = low_item->seq;
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/* it needs to work if seqnum wraps */
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if (high_seqnum >= low_seqnum) {
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result = (guint32) (high_seqnum - low_seqnum);
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} else {
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result = (guint32) (high_seqnum + G_MAXUINT16 + 1 - low_seqnum);
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}
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return result;
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}
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void
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rtp_storage_stream_resize_and_add_item (RtpStorageStream * stream,
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GstClockTime size_time, GstBuffer * buffer, guint8 pt, guint16 seq)
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{
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GstClockTime arrival_time = GST_BUFFER_DTS_OR_PTS (buffer);
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/* These limits match those of the jittebuffer, we keep a couple more
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* packets to avoid races as it can be queried after the output of the
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* jitterbuffer.
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*/
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if (rtp_storage_stream_get_seqnum_diff (stream) >= 32765 ||
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stream->queue.length > 10100) {
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RtpStorageItem *item = g_queue_pop_tail (&stream->queue);
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GST_WARNING ("Queue too big, removing pt=%d seq=%d for ssrc=%08x",
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item->pt, item->seq, stream->ssrc);
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rtp_storage_item_free (item);
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}
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if (G_LIKELY (GST_CLOCK_TIME_IS_VALID (arrival_time))) {
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if (G_LIKELY (GST_CLOCK_TIME_IS_VALID (stream->max_arrival_time)))
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stream->max_arrival_time = MAX (stream->max_arrival_time, arrival_time);
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else
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stream->max_arrival_time = arrival_time;
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rtp_storage_stream_resize (stream, size_time);
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rtp_storage_stream_add_item (stream, buffer, pt, seq);
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} else {
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rtp_storage_stream_add_item (stream, buffer, pt, seq);
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}
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}
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RtpStorageStream *
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rtp_storage_stream_new (guint32 ssrc)
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{
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RtpStorageStream *ret = g_slice_new0 (RtpStorageStream);
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ret->max_arrival_time = GST_CLOCK_TIME_NONE;
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ret->ssrc = ssrc;
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g_mutex_init (&ret->stream_lock);
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return ret;
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}
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void
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rtp_storage_stream_free (RtpStorageStream * stream)
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{
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STREAM_LOCK (stream);
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while (stream->queue.length)
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rtp_storage_item_free (g_queue_pop_tail (&stream->queue));
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STREAM_UNLOCK (stream);
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g_mutex_clear (&stream->stream_lock);
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g_slice_free (RtpStorageStream, stream);
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}
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void
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rtp_storage_stream_add_item (RtpStorageStream * stream, GstBuffer * buffer,
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guint8 pt, guint16 seq)
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{
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RtpStorageItem *item = rtp_storage_item_new (buffer, pt, seq);
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GList *sibling = g_queue_find_custom (&stream->queue, item,
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(GCompareFunc) rtp_storage_item_compare);
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g_queue_insert_before (&stream->queue, sibling, item);
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}
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GstBufferList *
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rtp_storage_stream_get_packets_for_recovery (RtpStorageStream * stream,
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guint8 pt_fec, guint16 lost_seq)
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{
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guint ret_length = 0;
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GList *end = NULL;
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GList *start = NULL;
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gboolean saw_fec = TRUE; /* To initialize the start pointer in the loop below */
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GList *it;
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/* Looking for media stream chunk with FEC packets at the end, which could
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* can have the lost packet. For example:
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*
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* |#10 FEC| |#9 FEC| |#8| ... |#6| |#5 FEC| |#4 FEC| |#3 FEC| |#2| |#1| |#0|
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*
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* Say @lost_seq = 7. Want to return bufferlist with packets [#6 : #10]. Other
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* packets are not relevant for recovery of packet 7.
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*
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* Or the lost packet can be in the storage. In that case single packet is returned.
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* It can happen if:
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* - it could have arrived right after it was considered lost (more of a corner case)
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* - it was recovered together with the other lost packet (most likely)
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*/
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for (it = stream->queue.tail; it; it = it->prev) {
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RtpStorageItem *item = it->data;
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gboolean found_end = FALSE;
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/* Is the buffer we lost in the storage? */
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if (item->seq == lost_seq) {
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start = it;
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end = it;
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ret_length = 1;
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break;
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}
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if (pt_fec == item->pt) {
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gint seq_diff = gst_rtp_buffer_compare_seqnum (lost_seq, item->seq);
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if (seq_diff >= 0) {
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if (it->prev) {
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gboolean media_next =
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pt_fec != ((RtpStorageItem *) it->prev->data)->pt;
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found_end = media_next;
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} else
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found_end = TRUE;
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}
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saw_fec = TRUE;
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} else if (saw_fec) {
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saw_fec = FALSE;
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start = it;
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ret_length = 0;
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}
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++ret_length;
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if (found_end) {
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end = it;
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break;
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}
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}
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if (end && !start)
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start = end;
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if (start && end) {
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GstBufferList *ret = gst_buffer_list_new_sized (ret_length);
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GList *it;
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GST_LOG ("Found %u buffers with lost seq=%d for ssrc=%08x, creating %"
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GST_PTR_FORMAT, ret_length, lost_seq, stream->ssrc, ret);
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for (it = start; it != end->prev; it = it->prev)
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gst_buffer_list_add (ret,
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gst_buffer_ref (((RtpStorageItem *) it->data)->buffer));
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return ret;
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}
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return NULL;
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}
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GstBuffer *
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rtp_storage_stream_get_redundant_packet (RtpStorageStream * stream,
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guint16 lost_seq)
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{
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GList *it;
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for (it = stream->queue.head; it; it = it->next) {
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RtpStorageItem *item = it->data;
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if (item->seq == lost_seq) {
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GST_LOG ("Found buffer pt=%u seq=%u for ssrc=%08x %" GST_PTR_FORMAT,
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item->pt, item->seq, stream->ssrc, item->buffer);
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return gst_buffer_ref (item->buffer);
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}
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}
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GST_DEBUG ("Could not find packet with seq=%u for ssrc=%08x",
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lost_seq, stream->ssrc);
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return NULL;
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}
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