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/* GStreamer plugin for forward error correction
* Copyright (C) 2017 Pexip
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Author: Mikhail Fludkov <misha@pexip.com>
*/
#include "rtpstoragestream.h"
static RtpStorageItem *
rtp_storage_item_new (GstBuffer * buffer, guint8 pt, guint16 seq)
{
RtpStorageItem *ret = g_slice_new0 (RtpStorageItem);
ret->buffer = buffer;
ret->pt = pt;
ret->seq = seq;
return ret;
}
static void
rtp_storage_item_free (RtpStorageItem * item)
{
g_assert (item->buffer != NULL);
gst_buffer_unref (item->buffer);
g_slice_free (RtpStorageItem, item);
}
static gint
rtp_storage_item_compare (gconstpointer a, gconstpointer b, gpointer userdata)
{
gint seq_diff = gst_rtp_buffer_compare_seqnum (
((RtpStorageItem const *) a)->seq, ((RtpStorageItem const *) b)->seq);
if (seq_diff >= 0)
return 0;
return 1;
}
static void
rtp_storage_stream_resize (RtpStorageStream * stream, GstClockTime size_time)
{
GList *it;
guint i, too_old_buffers_num = 0;
g_assert (GST_CLOCK_TIME_IS_VALID (stream->max_arrival_time));
g_assert (GST_CLOCK_TIME_IS_VALID (size_time));
g_assert_cmpint (size_time, >, 0);
/* Iterating from oldest sequence numbers to newest */
for (i = 0, it = stream->queue.tail; it; it = it->prev, ++i) {
RtpStorageItem *item = it->data;
GstClockTime arrival_time = GST_BUFFER_DTS_OR_PTS (item->buffer);
if (GST_CLOCK_TIME_IS_VALID (arrival_time)) {
if (stream->max_arrival_time - arrival_time > size_time) {
too_old_buffers_num = i + 1;
} else
break;
}
}
for (guint i = 0; i < too_old_buffers_num; ++i) {
RtpStorageItem *item = g_queue_pop_tail (&stream->queue);
rtp_storage_item_free (item);
}
}
void
rtp_storage_stream_resize_and_add_item (RtpStorageStream * stream,
GstClockTime size_time, GstBuffer * buffer, guint8 pt, guint16 seq)
{
GstClockTime arrival_time = GST_BUFFER_DTS_OR_PTS (buffer);
if (G_LIKELY (GST_CLOCK_TIME_IS_VALID (arrival_time))) {
if (G_LIKELY (GST_CLOCK_TIME_IS_VALID (stream->max_arrival_time)))
stream->max_arrival_time = MAX (stream->max_arrival_time, arrival_time);
else
stream->max_arrival_time = arrival_time;
rtp_storage_stream_resize (stream, size_time);
rtp_storage_stream_add_item (stream, buffer, pt, seq);
} else {
rtp_storage_stream_add_item (stream, buffer, pt, seq);
}
}
RtpStorageStream *
rtp_storage_stream_new (guint32 ssrc)
{
RtpStorageStream *ret = g_slice_new0 (RtpStorageStream);
ret->max_arrival_time = GST_CLOCK_TIME_NONE;
ret->ssrc = ssrc;
g_mutex_init (&ret->stream_lock);
return ret;
}
void
rtp_storage_stream_free (RtpStorageStream * stream)
{
STREAM_LOCK (stream);
while (stream->queue.length)
rtp_storage_item_free (g_queue_pop_tail (&stream->queue));
STREAM_UNLOCK (stream);
g_mutex_clear (&stream->stream_lock);
g_slice_free (RtpStorageStream, stream);
}
void
rtp_storage_stream_add_item (RtpStorageStream * stream, GstBuffer * buffer,
guint8 pt, guint16 seq)
{
RtpStorageItem *item = rtp_storage_item_new (buffer, pt, seq);
GList *sibling = g_queue_find_custom (&stream->queue, item,
(GCompareFunc) rtp_storage_item_compare);
g_queue_insert_before (&stream->queue, sibling, item);
}
GstBufferList *
rtp_storage_stream_get_packets_for_recovery (RtpStorageStream * stream,
guint8 pt_fec, guint16 lost_seq)
{
guint ret_length = 0;
GList *end = NULL;
GList *start = NULL;
gboolean saw_fec = TRUE; /* To initialize the start pointer in the loop below */
/* Looking for media stream chunk with FEC packets at the end, which could
* can have the lost packet. For example:
*
* |#10 FEC| |#9 FEC| |#8| ... |#6| |#5 FEC| |#4 FEC| |#3 FEC| |#2| |#1| |#0|
*
* Say @lost_seq = 7. Want to return bufferlist with packets [#6 : #10]. Other
* packets are not relevant for recovery of packet 7.
*
* Or the lost packet can be in the storage. In that case single packet is returned.
* It can happen if:
* - it could have arrived right after it was considered lost (more of a corner case)
* - it was recovered together with the other lost packet (most likely)
*/
for (GList * it = stream->queue.tail; it; it = it->prev) {
RtpStorageItem *item = it->data;
gboolean found_end = FALSE;
/* Is the buffer we lost in the storage? */
if (item->seq == lost_seq) {
start = it;
end = it;
ret_length = 1;
break;
}
if (pt_fec == item->pt) {
gint seq_diff = gst_rtp_buffer_compare_seqnum (lost_seq, item->seq);
if (seq_diff >= 0) {
if (it->prev) {
gboolean media_next =
pt_fec != ((RtpStorageItem *) it->prev->data)->pt;
found_end = media_next;
} else
found_end = TRUE;
}
saw_fec = TRUE;
} else if (saw_fec) {
saw_fec = FALSE;
start = it;
ret_length = 0;
}
++ret_length;
if (found_end) {
end = it;
break;
}
}
if (end && !start)
start = end;
if (start && end) {
GstBufferList *ret = gst_buffer_list_new_sized (ret_length);
for (GList * it = start; it != end->prev; it = it->prev)
gst_buffer_list_add (ret,
gst_buffer_ref (((RtpStorageItem *) it->data)->buffer));
return ret;
}
return NULL;
}
GstBuffer *
rtp_storage_stream_get_redundant_packet (RtpStorageStream * stream,
guint16 lost_seq)
{
for (GList * it = stream->queue.head; it; it = it->next) {
RtpStorageItem *item = it->data;
if (item->seq == lost_seq)
return gst_buffer_ref (item->buffer);
}
return NULL;
}
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