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gstreamer/subprojects/gst-plugins-good/gst/rtpmanager/rtptwcc.c

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/* GStreamer
* Copyright (C) 2019 Pexip (http://pexip.com/)
* @author: Havard Graff <havard@pexip.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "rtptwcc.h"
#include <gst/rtp/gstrtcpbuffer.h>
#include <gst/base/gstbitreader.h>
#include <gst/base/gstbitwriter.h>
GST_DEBUG_CATEGORY_EXTERN (rtp_session_debug);
#define GST_CAT_DEFAULT rtp_session_debug
#define TWCC_EXTMAP_STR "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01"
#define REF_TIME_UNIT (64 * GST_MSECOND)
#define DELTA_UNIT (250 * GST_USECOND)
#define MAX_TS_DELTA (0xff * DELTA_UNIT)
#define STATUS_VECTOR_MAX_CAPACITY 14
#define STATUS_VECTOR_TWO_BIT_MAX_CAPACITY 7
typedef enum
{
RTP_TWCC_CHUNK_TYPE_RUN_LENGTH = 0,
RTP_TWCC_CHUNK_TYPE_STATUS_VECTOR = 1,
} RTPTWCCChunkType;
typedef struct
{
guint8 base_seqnum[2];
guint8 packet_count[2];
guint8 base_time[3];
guint8 fb_pkt_count[1];
} RTPTWCCHeader;
typedef struct
{
GstClockTime ts;
guint16 seqnum;
gint64 delta;
RTPTWCCPacketStatus status;
guint16 missing_run;
guint equal_run;
} RecvPacket;
typedef struct
{
GstClockTime ts;
GstClockTime socket_ts;
GstClockTime remote_ts;
guint16 seqnum;
guint8 pt;
guint size;
gboolean lost;
} SentPacket;
struct _RTPTWCCManager
{
GObject object;
guint8 send_ext_id;
guint8 recv_ext_id;
guint16 send_seqnum;
guint mtu;
guint max_packets_per_rtcp;
GArray *recv_packets;
guint64 fb_pkt_count;
gint32 last_seqnum;
GArray *sent_packets;
GArray *parsed_packets;
GQueue *rtcp_buffers;
guint64 recv_sender_ssrc;
guint64 recv_media_ssrc;
guint16 expected_recv_seqnum;
guint16 packet_count_no_marker;
gboolean first_fci_parse;
guint16 expected_parsed_seqnum;
guint8 expected_parsed_fb_pkt_count;
GstClockTime next_feedback_send_time;
GstClockTime feedback_interval;
};
G_DEFINE_TYPE (RTPTWCCManager, rtp_twcc_manager, G_TYPE_OBJECT);
static void
rtp_twcc_manager_init (RTPTWCCManager * twcc)
{
twcc->recv_packets = g_array_new (FALSE, FALSE, sizeof (RecvPacket));
twcc->sent_packets = g_array_new (FALSE, FALSE, sizeof (SentPacket));
twcc->parsed_packets = g_array_new (FALSE, FALSE, sizeof (RecvPacket));
twcc->rtcp_buffers = g_queue_new ();
twcc->last_seqnum = -1;
twcc->recv_media_ssrc = -1;
twcc->recv_sender_ssrc = -1;
twcc->first_fci_parse = TRUE;
twcc->feedback_interval = GST_CLOCK_TIME_NONE;
twcc->next_feedback_send_time = GST_CLOCK_TIME_NONE;
}
static void
rtp_twcc_manager_finalize (GObject * object)
{
RTPTWCCManager *twcc = RTP_TWCC_MANAGER_CAST (object);
g_array_unref (twcc->recv_packets);
g_array_unref (twcc->sent_packets);
g_array_unref (twcc->parsed_packets);
g_queue_free_full (twcc->rtcp_buffers, (GDestroyNotify) gst_buffer_unref);
G_OBJECT_CLASS (rtp_twcc_manager_parent_class)->finalize (object);
}
static void
rtp_twcc_manager_class_init (RTPTWCCManagerClass * klass)
{
GObjectClass *gobject_class = (GObjectClass *) klass;
gobject_class->finalize = rtp_twcc_manager_finalize;
}
RTPTWCCManager *
rtp_twcc_manager_new (guint mtu)
{
RTPTWCCManager *twcc = g_object_new (RTP_TYPE_TWCC_MANAGER, NULL);
rtp_twcc_manager_set_mtu (twcc, mtu);
return twcc;
}
static void
recv_packet_init (RecvPacket * packet, guint16 seqnum, RTPPacketInfo * pinfo)
{
memset (packet, 0, sizeof (RecvPacket));
packet->seqnum = seqnum;
if (GST_CLOCK_TIME_IS_VALID (pinfo->arrival_time))
packet->ts = pinfo->arrival_time;
else
packet->ts = pinfo->current_time;
}
static guint8
_get_extmap_id_for_attribute (const GstStructure * s, const gchar * ext_name)
{
guint i;
guint8 extmap_id = 0;
guint n_fields = gst_structure_n_fields (s);
for (i = 0; i < n_fields; i++) {
const gchar *field_name = gst_structure_nth_field_name (s, i);
if (g_str_has_prefix (field_name, "extmap-")) {
const gchar *str = gst_structure_get_string (s, field_name);
if (str && g_strcmp0 (str, ext_name) == 0) {
gint64 id = g_ascii_strtoll (field_name + 7, NULL, 10);
if (id > 0 && id < 15) {
extmap_id = id;
break;
}
}
}
}
return extmap_id;
}
void
rtp_twcc_manager_parse_recv_ext_id (RTPTWCCManager * twcc,
const GstStructure * s)
{
guint8 recv_ext_id = _get_extmap_id_for_attribute (s, TWCC_EXTMAP_STR);
if (recv_ext_id > 0) {
twcc->recv_ext_id = recv_ext_id;
GST_INFO ("TWCC enabled for recv using extension id: %u",
twcc->recv_ext_id);
}
}
void
rtp_twcc_manager_parse_send_ext_id (RTPTWCCManager * twcc,
const GstStructure * s)
{
guint8 send_ext_id = _get_extmap_id_for_attribute (s, TWCC_EXTMAP_STR);
if (send_ext_id > 0) {
twcc->send_ext_id = send_ext_id;
GST_INFO ("TWCC enabled for send using extension id: %u",
twcc->send_ext_id);
}
}
void
rtp_twcc_manager_set_mtu (RTPTWCCManager * twcc, guint mtu)
{
twcc->mtu = mtu;
/* the absolute worst case is that 7 packets uses
header (4 * 4 * 4) 32 bytes) and
packet_chunk 2 bytes +
recv_deltas (2 * 7) 14 bytes */
twcc->max_packets_per_rtcp = ((twcc->mtu - 32) * 7) / (2 + 14);
}
void
rtp_twcc_manager_set_feedback_interval (RTPTWCCManager * twcc,
GstClockTime feedback_interval)
{
twcc->feedback_interval = feedback_interval;
}
GstClockTime
rtp_twcc_manager_get_feedback_interval (RTPTWCCManager * twcc)
{
return twcc->feedback_interval;
}
static gboolean
_get_twcc_seqnum_data (RTPPacketInfo * pinfo, guint8 ext_id, gpointer * data)
{
gboolean ret = FALSE;
guint size;
if (pinfo->header_ext &&
gst_rtp_buffer_get_extension_onebyte_header_from_bytes (pinfo->header_ext,
pinfo->header_ext_bit_pattern, ext_id, 0, data, &size)) {
if (size == 2)
ret = TRUE;
}
return ret;
}
static void
_set_twcc_seqnum_data (GstBuffer * buf, guint8 ext_id, guint16 seqnum)
{
GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
gpointer data;
if (gst_rtp_buffer_map (buf, GST_MAP_READWRITE, &rtp)) {
if (gst_rtp_buffer_get_extension_onebyte_header (&rtp,
ext_id, 0, &data, NULL)) {
GST_WRITE_UINT16_BE (data, seqnum);
}
gst_rtp_buffer_unmap (&rtp);
}
}
static guint16
rtp_twcc_manager_set_send_twcc_seqnum (RTPTWCCManager * twcc,
RTPPacketInfo * pinfo)
{
guint16 seqnum = twcc->send_seqnum++;
pinfo->data = gst_buffer_make_writable (pinfo->data);
_set_twcc_seqnum_data (pinfo->data, twcc->send_ext_id, seqnum);
return seqnum;
}
static gint32
rtp_twcc_manager_get_recv_twcc_seqnum (RTPTWCCManager * twcc,
RTPPacketInfo * pinfo)
{
gint32 val = -1;
gpointer data;
if (twcc->recv_ext_id == 0)
return val;
if (_get_twcc_seqnum_data (pinfo, twcc->recv_ext_id, &data)) {
val = GST_READ_UINT16_BE (data);
}
return val;
}
static gint
_twcc_seqnum_sort (gconstpointer a, gconstpointer b)
{
gint32 seqa = ((RecvPacket *) a)->seqnum;
gint32 seqb = ((RecvPacket *) b)->seqnum;
gint res = seqa - seqb;
if (res < -65000)
res = 1;
if (res > 65000)
res = -1;
return res;
}
static void
rtp_twcc_write_recv_deltas (guint8 * fci_data, GArray * twcc_packets)
{
guint i;
for (i = 0; i < twcc_packets->len; i++) {
RecvPacket *pkt = &g_array_index (twcc_packets, RecvPacket, i);
if (pkt->status == RTP_TWCC_PACKET_STATUS_SMALL_DELTA) {
GST_WRITE_UINT8 (fci_data, pkt->delta);
fci_data += 1;
} else if (pkt->status == RTP_TWCC_PACKET_STATUS_LARGE_NEGATIVE_DELTA) {
GST_WRITE_UINT16_BE (fci_data, pkt->delta);
fci_data += 2;
}
}
}
static void
rtp_twcc_write_run_length_chunk (GArray * packet_chunks,
RTPTWCCPacketStatus status, guint run_length)
{
guint written = 0;
while (written < run_length) {
GstBitWriter writer;
guint16 data = 0;
guint len = MIN (run_length - written, 8191);
GST_LOG ("Writing a run-length of %u with status %u", len, status);
gst_bit_writer_init_with_data (&writer, (guint8 *) & data, 2, FALSE);
gst_bit_writer_put_bits_uint8 (&writer, RTP_TWCC_CHUNK_TYPE_RUN_LENGTH, 1);
gst_bit_writer_put_bits_uint8 (&writer, status, 2);
gst_bit_writer_put_bits_uint16 (&writer, len, 13);
g_array_append_val (packet_chunks, data);
written += len;
}
}
typedef struct
{
GArray *packet_chunks;
GstBitWriter writer;
guint16 data;
guint symbol_size;
} ChunkBitWriter;
static void
chunk_bit_writer_reset (ChunkBitWriter * writer)
{
writer->data = 0;
gst_bit_writer_init_with_data (&writer->writer,
(guint8 *) & writer->data, 2, FALSE);
gst_bit_writer_put_bits_uint8 (&writer->writer,
RTP_TWCC_CHUNK_TYPE_STATUS_VECTOR, 1);
/* 1 for 2-bit symbol-size, 0 for 1-bit */
gst_bit_writer_put_bits_uint8 (&writer->writer, writer->symbol_size - 1, 1);
}
static void
chunk_bit_writer_configure (ChunkBitWriter * writer, guint symbol_size)
{
writer->symbol_size = symbol_size;
chunk_bit_writer_reset (writer);
}
static gboolean
chunk_bit_writer_is_empty (ChunkBitWriter * writer)
{
return writer->writer.bit_size == 2;
}
static gboolean
chunk_bit_writer_is_full (ChunkBitWriter * writer)
{
return writer->writer.bit_size == 16;
}
static guint
chunk_bit_writer_get_available_slots (ChunkBitWriter * writer)
{
return (16 - writer->writer.bit_size) / writer->symbol_size;
}
static guint
chunk_bit_writer_get_total_slots (ChunkBitWriter * writer)
{
return STATUS_VECTOR_MAX_CAPACITY / writer->symbol_size;
}
static void
chunk_bit_writer_flush (ChunkBitWriter * writer)
{
/* don't append a chunk if no bits have been written */
if (!chunk_bit_writer_is_empty (writer)) {
g_array_append_val (writer->packet_chunks, writer->data);
chunk_bit_writer_reset (writer);
}
}
static void
chunk_bit_writer_init (ChunkBitWriter * writer,
GArray * packet_chunks, guint symbol_size)
{
writer->packet_chunks = packet_chunks;
chunk_bit_writer_configure (writer, symbol_size);
}
static void
chunk_bit_writer_write (ChunkBitWriter * writer, RTPTWCCPacketStatus status)
{
gst_bit_writer_put_bits_uint8 (&writer->writer, status, writer->symbol_size);
if (chunk_bit_writer_is_full (writer)) {
chunk_bit_writer_flush (writer);
}
}
static void
rtp_twcc_write_status_vector_chunk (ChunkBitWriter * writer, RecvPacket * pkt)
{
if (pkt->missing_run > 0) {
guint available = chunk_bit_writer_get_available_slots (writer);
guint total = chunk_bit_writer_get_total_slots (writer);
guint i;
if (pkt->missing_run > (available + total)) {
/* here it is better to finish up the current status-chunk and then
go for run-length */
for (i = 0; i < available; i++) {
chunk_bit_writer_write (writer, RTP_TWCC_PACKET_STATUS_NOT_RECV);
}
rtp_twcc_write_run_length_chunk (writer->packet_chunks,
RTP_TWCC_PACKET_STATUS_NOT_RECV, pkt->missing_run - available);
} else {
for (i = 0; i < pkt->missing_run; i++) {
chunk_bit_writer_write (writer, RTP_TWCC_PACKET_STATUS_NOT_RECV);
}
}
}
chunk_bit_writer_write (writer, pkt->status);
}
typedef struct
{
RecvPacket *equal;
} RunLengthHelper;
static void
run_lenght_helper_update (RunLengthHelper * rlh, RecvPacket * pkt)
{
/* for missing packets we reset */
if (pkt->missing_run > 0) {
rlh->equal = NULL;
}
/* all status equal run */
if (rlh->equal == NULL) {
rlh->equal = pkt;
rlh->equal->equal_run = 0;
}
if (rlh->equal->status == pkt->status) {
rlh->equal->equal_run++;
} else {
rlh->equal = pkt;
rlh->equal->equal_run = 1;
}
}
static guint
_get_max_packets_capacity (guint symbol_size)
{
if (symbol_size == 2)
return STATUS_VECTOR_TWO_BIT_MAX_CAPACITY;
return STATUS_VECTOR_MAX_CAPACITY;
}
static gboolean
_pkt_fits_run_length_chunk (RecvPacket * pkt, guint packets_per_chunks,
guint remaining_packets)
{
if (pkt->missing_run == 0) {
/* we have more or the same equal packets than the ones we can write in to a status chunk */
if (pkt->equal_run >= packets_per_chunks)
return TRUE;
/* we have more than one equal and not enough space for the remainings */
if (pkt->equal_run > 1 && remaining_packets > STATUS_VECTOR_MAX_CAPACITY)
return TRUE;
/* we have all equal packets for the remaining to write */
if (pkt->equal_run == remaining_packets)
return TRUE;
}
return FALSE;
}
static void
rtp_twcc_write_chunks (GArray * packet_chunks,
GArray * twcc_packets, guint symbol_size)
{
ChunkBitWriter writer;
guint i;
guint packets_per_chunks = _get_max_packets_capacity (symbol_size);
chunk_bit_writer_init (&writer, packet_chunks, symbol_size);
for (i = 0; i < twcc_packets->len; i++) {
RecvPacket *pkt = &g_array_index (twcc_packets, RecvPacket, i);
guint remaining_packets = twcc_packets->len - i;
GST_LOG
("About to write pkt: #%u missing_run: %u equal_run: %u status: %u, remaining_packets: %u",
pkt->seqnum, pkt->missing_run, pkt->equal_run, pkt->status,
remaining_packets);
/* we can only start a run-length chunk if the status-chunk is
completed */
if (chunk_bit_writer_is_empty (&writer)) {
/* first write in any preceeding gaps, we use run-length
if it would take up more than one chunk (14/7) */
if (pkt->missing_run > packets_per_chunks) {
rtp_twcc_write_run_length_chunk (packet_chunks,
RTP_TWCC_PACKET_STATUS_NOT_RECV, pkt->missing_run);
}
/* we have a run of the same status, write a run-length chunk and skip
to the next point */
if (_pkt_fits_run_length_chunk (pkt, packets_per_chunks,
remaining_packets)) {
rtp_twcc_write_run_length_chunk (packet_chunks,
pkt->status, pkt->equal_run);
i += pkt->equal_run - 1;
continue;
}
}
GST_LOG ("i=%u: Writing a %u-bit vector of status: %u",
i, symbol_size, pkt->status);
rtp_twcc_write_status_vector_chunk (&writer, pkt);
}
chunk_bit_writer_flush (&writer);
}
static void
rtp_twcc_manager_add_fci (RTPTWCCManager * twcc, GstRTCPPacket * packet)
{
RecvPacket *first, *last, *prev;
guint16 packet_count;
GstClockTime base_time;
GstClockTime ts_rounded;
guint i;
GArray *packet_chunks = g_array_new (FALSE, FALSE, 2);
RTPTWCCHeader header;
guint header_size = sizeof (RTPTWCCHeader);
guint packet_chunks_size;
guint recv_deltas_size = 0;
guint16 fci_length;
guint16 fci_chunks;
guint8 *fci_data;
guint8 *fci_data_ptr;
RunLengthHelper rlh = { NULL };
guint symbol_size = 1;
GstClockTimeDiff delta_ts;
gint64 delta_ts_rounded;
guint8 fb_pkt_count;
g_array_sort (twcc->recv_packets, _twcc_seqnum_sort);
/* get first and last packet */
first = &g_array_index (twcc->recv_packets, RecvPacket, 0);
last =
&g_array_index (twcc->recv_packets, RecvPacket,
twcc->recv_packets->len - 1);
packet_count = last->seqnum - first->seqnum + 1;
base_time = first->ts / REF_TIME_UNIT;
fb_pkt_count = (guint8) (twcc->fb_pkt_count % G_MAXUINT8);
GST_WRITE_UINT16_BE (header.base_seqnum, first->seqnum);
GST_WRITE_UINT16_BE (header.packet_count, packet_count);
GST_WRITE_UINT24_BE (header.base_time, base_time);
GST_WRITE_UINT8 (header.fb_pkt_count, fb_pkt_count);
base_time *= REF_TIME_UNIT;
ts_rounded = base_time;
GST_DEBUG ("Created TWCC feedback: base_seqnum: #%u, packet_count: %u, "
"base_time %" GST_TIME_FORMAT " fb_pkt_count: %u",
first->seqnum, packet_count, GST_TIME_ARGS (base_time), fb_pkt_count);
twcc->fb_pkt_count++;
twcc->expected_recv_seqnum = first->seqnum + packet_count;
/* calculate all deltas and check for gaps etc */
prev = first;
for (i = 0; i < twcc->recv_packets->len; i++) {
RecvPacket *pkt = &g_array_index (twcc->recv_packets, RecvPacket, i);
if (i != 0) {
pkt->missing_run = pkt->seqnum - prev->seqnum - 1;
}
delta_ts = GST_CLOCK_DIFF (ts_rounded, pkt->ts);
pkt->delta = delta_ts / DELTA_UNIT;
delta_ts_rounded = pkt->delta * DELTA_UNIT;
ts_rounded += delta_ts_rounded;
if (delta_ts_rounded < 0 || delta_ts_rounded > MAX_TS_DELTA) {
pkt->status = RTP_TWCC_PACKET_STATUS_LARGE_NEGATIVE_DELTA;
recv_deltas_size += 2;
symbol_size = 2;
} else {
pkt->status = RTP_TWCC_PACKET_STATUS_SMALL_DELTA;
recv_deltas_size += 1;
}
run_lenght_helper_update (&rlh, pkt);
GST_LOG ("pkt: #%u, ts: %" GST_TIME_FORMAT
" ts_rounded: %" GST_TIME_FORMAT
" delta_ts: %" GST_STIME_FORMAT
" delta_ts_rounded: %" GST_STIME_FORMAT
" missing_run: %u, status: %u", pkt->seqnum,
GST_TIME_ARGS (pkt->ts), GST_TIME_ARGS (ts_rounded),
GST_STIME_ARGS (delta_ts), GST_STIME_ARGS (delta_ts_rounded),
pkt->missing_run, pkt->status);
prev = pkt;
}
rtp_twcc_write_chunks (packet_chunks, twcc->recv_packets, symbol_size);
packet_chunks_size = packet_chunks->len * 2;
fci_length = header_size + packet_chunks_size + recv_deltas_size;
fci_chunks = (fci_length - 1) / sizeof (guint32) + 1;
if (!gst_rtcp_packet_fb_set_fci_length (packet, fci_chunks)) {
GST_ERROR ("Could not fit: %u packets", packet_count);
g_assert_not_reached ();
}
fci_data = gst_rtcp_packet_fb_get_fci (packet);
fci_data_ptr = fci_data;
memcpy (fci_data_ptr, &header, header_size);
fci_data_ptr += header_size;
memcpy (fci_data_ptr, packet_chunks->data, packet_chunks_size);
fci_data_ptr += packet_chunks_size;
rtp_twcc_write_recv_deltas (fci_data_ptr, twcc->recv_packets);
GST_MEMDUMP ("twcc-header:", (guint8 *) & header, header_size);
GST_MEMDUMP ("packet-chunks:", (guint8 *) packet_chunks->data,
packet_chunks_size);
GST_MEMDUMP ("full fci:", fci_data, fci_length);
g_array_unref (packet_chunks);
g_array_set_size (twcc->recv_packets, 0);
}
static void
rtp_twcc_manager_create_feedback (RTPTWCCManager * twcc)
{
GstBuffer *buf;
GstRTCPBuffer rtcp = GST_RTCP_BUFFER_INIT;
GstRTCPPacket packet;
buf = gst_rtcp_buffer_new (twcc->mtu);
gst_rtcp_buffer_map (buf, GST_MAP_READWRITE, &rtcp);
gst_rtcp_buffer_add_packet (&rtcp, GST_RTCP_TYPE_RTPFB, &packet);
gst_rtcp_packet_fb_set_type (&packet, GST_RTCP_RTPFB_TYPE_TWCC);
if (twcc->recv_sender_ssrc != 1)
gst_rtcp_packet_fb_set_sender_ssrc (&packet, twcc->recv_sender_ssrc);
gst_rtcp_packet_fb_set_media_ssrc (&packet, twcc->recv_media_ssrc);
rtp_twcc_manager_add_fci (twcc, &packet);
gst_rtcp_buffer_unmap (&rtcp);
g_queue_push_tail (twcc->rtcp_buffers, buf);
}
/* we have calculated a (very pessimistic) max-packets per RTCP feedback,
so this is to make sure we don't exceed that */
static gboolean
_exceeds_max_packets (RTPTWCCManager * twcc, guint16 seqnum)
{
if (twcc->recv_packets->len + 1 > twcc->max_packets_per_rtcp)
return TRUE;
return FALSE;
}
/* in this case we could have lost the packet with the marker bit,
so with a large (30) amount of packets, lost packets and still no marker,
we send a feedback anyway */
static gboolean
_many_packets_some_lost (RTPTWCCManager * twcc, guint16 seqnum)
{
RecvPacket *first;
guint16 packet_count;
guint received_packets = twcc->recv_packets->len;
guint lost_packets;
if (received_packets == 0)
return FALSE;
first = &g_array_index (twcc->recv_packets, RecvPacket, 0);
packet_count = seqnum - first->seqnum + 1;
/* check if we lost half of the threshold */
lost_packets = packet_count - received_packets;
if (received_packets >= 30 && lost_packets >= 60)
return TRUE;
/* we have lost the marker bit for some and lost some */
if (twcc->packet_count_no_marker >= 10 && lost_packets >= 60)
return TRUE;
return FALSE;
}
gboolean
rtp_twcc_manager_recv_packet (RTPTWCCManager * twcc, RTPPacketInfo * pinfo)
{
gboolean send_feedback = FALSE;
RecvPacket packet;
gint32 seqnum;
gint diff;
seqnum = rtp_twcc_manager_get_recv_twcc_seqnum (twcc, pinfo);
if (seqnum == -1)
return FALSE;
/* if this packet would exceed the capacity of our MTU, we create a feedback
with the current packets, and start over with this one */
if (_exceeds_max_packets (twcc, seqnum)) {
GST_INFO ("twcc-seqnum: %u would overflow max packets: %u, create feedback"
" with current packets", seqnum, twcc->max_packets_per_rtcp);
rtp_twcc_manager_create_feedback (twcc);
send_feedback = TRUE;
}
/* we can have multiple ssrcs here, so just pick the first one */
if (twcc->recv_media_ssrc == -1)
twcc->recv_media_ssrc = pinfo->ssrc;
/* check if we are reordered, and treat it as lost if we already sent
a feedback msg with a higher seqnum. If the diff is huge, treat
it as a restart of a stream */
diff = gst_rtp_buffer_compare_seqnum (twcc->expected_recv_seqnum, seqnum);
if (twcc->fb_pkt_count > 0 && diff < 0) {
GST_INFO ("Received out of order packet (%u after %u), treating as lost",
seqnum, twcc->expected_recv_seqnum);
return FALSE;
}
if (twcc->recv_packets->len > 0) {
RecvPacket *last = &g_array_index (twcc->recv_packets, RecvPacket,
twcc->recv_packets->len - 1);
diff = gst_rtp_buffer_compare_seqnum (last->seqnum, seqnum);
if (diff == 0) {
GST_INFO ("Received duplicate packet (%u), dropping", seqnum);
return FALSE;
}
}
/* store the packet for Transport-wide RTCP feedback message */
recv_packet_init (&packet, seqnum, pinfo);
g_array_append_val (twcc->recv_packets, packet);
twcc->last_seqnum = seqnum;
GST_LOG ("Receive: twcc-seqnum: %u, pt: %u, marker: %d, ts: %"
GST_TIME_FORMAT, seqnum, pinfo->pt, pinfo->marker,
GST_TIME_ARGS (pinfo->arrival_time));
if (!pinfo->marker)
twcc->packet_count_no_marker++;
/* are we sending on an interval, or based on marker bit */
if (GST_CLOCK_TIME_IS_VALID (twcc->feedback_interval)) {
if (!GST_CLOCK_TIME_IS_VALID (twcc->next_feedback_send_time))
twcc->next_feedback_send_time =
pinfo->running_time + twcc->feedback_interval;
if (pinfo->running_time >= twcc->next_feedback_send_time) {
rtp_twcc_manager_create_feedback (twcc);
send_feedback = TRUE;
while (pinfo->running_time >= twcc->next_feedback_send_time)
twcc->next_feedback_send_time += twcc->feedback_interval;
}
} else if (pinfo->marker || _many_packets_some_lost (twcc, seqnum)) {
rtp_twcc_manager_create_feedback (twcc);
send_feedback = TRUE;
twcc->packet_count_no_marker = 0;
}
return send_feedback;
}
static void
_change_rtcp_fb_sender_ssrc (GstBuffer * buf, guint32 sender_ssrc)
{
GstRTCPBuffer rtcp = GST_RTCP_BUFFER_INIT;
GstRTCPPacket packet;
gst_rtcp_buffer_map (buf, GST_MAP_READWRITE, &rtcp);
gst_rtcp_buffer_get_first_packet (&rtcp, &packet);
gst_rtcp_packet_fb_set_sender_ssrc (&packet, sender_ssrc);
gst_rtcp_buffer_unmap (&rtcp);
}
GstBuffer *
rtp_twcc_manager_get_feedback (RTPTWCCManager * twcc, guint sender_ssrc)
{
GstBuffer *buf;
buf = g_queue_pop_head (twcc->rtcp_buffers);
if (buf && twcc->recv_sender_ssrc != sender_ssrc) {
_change_rtcp_fb_sender_ssrc (buf, sender_ssrc);
twcc->recv_sender_ssrc = sender_ssrc;
}
return buf;
}
static void
sent_packet_init (SentPacket * packet, guint16 seqnum, RTPPacketInfo * pinfo)
{
packet->seqnum = seqnum;
packet->ts = pinfo->current_time;
packet->size = pinfo->payload_len;
packet->pt = pinfo->pt;
packet->remote_ts = GST_CLOCK_TIME_NONE;
packet->socket_ts = GST_CLOCK_TIME_NONE;
packet->lost = FALSE;
}
void
rtp_twcc_manager_send_packet (RTPTWCCManager * twcc, RTPPacketInfo * pinfo)
{
SentPacket packet;
guint16 seqnum;
if (twcc->send_ext_id == 0)
return;
seqnum = rtp_twcc_manager_set_send_twcc_seqnum (twcc, pinfo);
sent_packet_init (&packet, seqnum, pinfo);
g_array_append_val (twcc->sent_packets, packet);
GST_LOG ("Send: twcc-seqnum: %u, pt: %u, marker: %d, ts: %"
GST_TIME_FORMAT, seqnum, pinfo->pt, pinfo->marker,
GST_TIME_ARGS (pinfo->current_time));
}
static void
_add_twcc_packet (GArray * twcc_packets, guint16 seqnum, guint status)
{
RTPTWCCPacket packet;
memset (&packet, 0, sizeof (RTPTWCCPacket));
packet.local_ts = GST_CLOCK_TIME_NONE;
packet.remote_ts = GST_CLOCK_TIME_NONE;
packet.local_delta = GST_CLOCK_STIME_NONE;
packet.remote_delta = GST_CLOCK_STIME_NONE;
packet.delta_delta = GST_CLOCK_STIME_NONE;
packet.seqnum = seqnum;
packet.status = status;
g_array_append_val (twcc_packets, packet);
}
static guint
_parse_run_length_chunk (GstBitReader * reader, GArray * twcc_packets,
guint16 seqnum_offset, guint remaining_packets)
{
guint16 run_length;
guint8 status_code;
guint i;
gst_bit_reader_get_bits_uint8 (reader, &status_code, 2);
gst_bit_reader_get_bits_uint16 (reader, &run_length, 13);
run_length = MIN (remaining_packets, run_length);
for (i = 0; i < run_length; i++) {
_add_twcc_packet (twcc_packets, seqnum_offset + i, status_code);
}
return run_length;
}
static guint
_parse_status_vector_chunk (GstBitReader * reader, GArray * twcc_packets,
guint16 seqnum_offset, guint remaining_packets)
{
guint8 symbol_size;
guint num_bits;
guint i;
gst_bit_reader_get_bits_uint8 (reader, &symbol_size, 1);
symbol_size += 1;
num_bits = MIN (remaining_packets, 14 / symbol_size);
for (i = 0; i < num_bits; i++) {
guint8 status_code;
if (gst_bit_reader_get_bits_uint8 (reader, &status_code, symbol_size))
_add_twcc_packet (twcc_packets, seqnum_offset + i, status_code);
}
return num_bits;
}
/* Remove all locally stored packets that has been reported
back to us */
static void
_prune_sent_packets (RTPTWCCManager * twcc, GArray * twcc_packets)
{
SentPacket *first;
RTPTWCCPacket *last;
guint16 last_idx;
if (twcc_packets->len == 0 || twcc->sent_packets->len == 0)
return;
first = &g_array_index (twcc->sent_packets, SentPacket, 0);
last = &g_array_index (twcc_packets, RTPTWCCPacket, twcc_packets->len - 1);
last_idx = last->seqnum - first->seqnum;
if (last_idx < twcc->sent_packets->len)
g_array_remove_range (twcc->sent_packets, 0, last_idx);
}
static void
_check_for_lost_packets (RTPTWCCManager * twcc, GArray * twcc_packets,
guint16 base_seqnum, guint16 packet_count, guint8 fb_pkt_count)
{
guint packets_lost;
gint8 fb_pkt_count_diff;
guint i;
/* first packet */
if (twcc->first_fci_parse) {
twcc->first_fci_parse = FALSE;
goto done;
}
fb_pkt_count_diff =
(gint8) (fb_pkt_count - twcc->expected_parsed_fb_pkt_count);
/* we have gone backwards, don't reset the expectations,
but process the packet nonetheless */
if (fb_pkt_count_diff < 0) {
GST_DEBUG ("feedback packet count going backwards (%u < %u)",
fb_pkt_count, twcc->expected_parsed_fb_pkt_count);
return;
}
/* we have jumped forwards, reset expectations, but don't trigger
lost packets in case the missing fb-packet(s) arrive later */
if (fb_pkt_count_diff > 0) {
GST_DEBUG ("feedback packet count jumped ahead (%u > %u)",
fb_pkt_count, twcc->expected_parsed_fb_pkt_count);
goto done;
}
if (base_seqnum < twcc->expected_parsed_seqnum) {
GST_DEBUG ("twcc seqnum is older than expected (%u < %u)", base_seqnum,
twcc->expected_parsed_seqnum);
return;
}
packets_lost = base_seqnum - twcc->expected_parsed_seqnum;
for (i = 0; i < packets_lost; i++) {
_add_twcc_packet (twcc_packets, twcc->expected_parsed_seqnum + i,
RTP_TWCC_PACKET_STATUS_NOT_RECV);
}
done:
twcc->expected_parsed_seqnum = base_seqnum + packet_count;
twcc->expected_parsed_fb_pkt_count = fb_pkt_count + 1;
return;
}
GArray *
rtp_twcc_manager_parse_fci (RTPTWCCManager * twcc,
guint8 * fci_data, guint fci_length)
{
GArray *twcc_packets;
guint16 base_seqnum;
guint16 packet_count;
GstClockTime base_time;
GstClockTime ts_rounded;
guint8 fb_pkt_count;
guint packets_parsed = 0;
guint fci_parsed;
guint i;
SentPacket *first_sent_pkt = NULL;
if (fci_length < 10) {
GST_WARNING ("Malformed TWCC RTCP feedback packet");
return NULL;
}
base_seqnum = GST_READ_UINT16_BE (&fci_data[0]);
packet_count = GST_READ_UINT16_BE (&fci_data[2]);
base_time = GST_READ_UINT24_BE (&fci_data[4]) * REF_TIME_UNIT;
fb_pkt_count = fci_data[7];
GST_DEBUG ("Parsed TWCC feedback: base_seqnum: #%u, packet_count: %u, "
"base_time %" GST_TIME_FORMAT " fb_pkt_count: %u",
base_seqnum, packet_count, GST_TIME_ARGS (base_time), fb_pkt_count);
twcc_packets = g_array_sized_new (FALSE, FALSE,
sizeof (RTPTWCCPacket), packet_count);
_check_for_lost_packets (twcc, twcc_packets,
base_seqnum, packet_count, fb_pkt_count);
fci_parsed = 8;
while (packets_parsed < packet_count && (fci_parsed + 1) < fci_length) {
GstBitReader reader = GST_BIT_READER_INIT (&fci_data[fci_parsed], 2);
guint8 chunk_type;
guint seqnum_offset = base_seqnum + packets_parsed;
guint remaining_packets = packet_count - packets_parsed;
gst_bit_reader_get_bits_uint8 (&reader, &chunk_type, 1);
if (chunk_type == RTP_TWCC_CHUNK_TYPE_RUN_LENGTH) {
packets_parsed += _parse_run_length_chunk (&reader,
twcc_packets, seqnum_offset, remaining_packets);
} else {
packets_parsed += _parse_status_vector_chunk (&reader,
twcc_packets, seqnum_offset, remaining_packets);
}
fci_parsed += 2;
}
if (twcc->sent_packets->len > 0)
first_sent_pkt = &g_array_index (twcc->sent_packets, SentPacket, 0);
ts_rounded = base_time;
for (i = 0; i < twcc_packets->len; i++) {
RTPTWCCPacket *pkt = &g_array_index (twcc_packets, RTPTWCCPacket, i);
gint16 delta = 0;
GstClockTimeDiff delta_ts;
if (pkt->status == RTP_TWCC_PACKET_STATUS_SMALL_DELTA) {
delta = fci_data[fci_parsed];
fci_parsed += 1;
} else if (pkt->status == RTP_TWCC_PACKET_STATUS_LARGE_NEGATIVE_DELTA) {
delta = GST_READ_UINT16_BE (&fci_data[fci_parsed]);
fci_parsed += 2;
}
if (fci_parsed > fci_length) {
GST_WARNING ("Malformed TWCC RTCP feedback packet");
g_array_set_size (twcc_packets, 0);
break;
}
if (pkt->status != RTP_TWCC_PACKET_STATUS_NOT_RECV) {
delta_ts = delta * DELTA_UNIT;
ts_rounded += delta_ts;
pkt->remote_ts = ts_rounded;
GST_LOG ("pkt: #%u, remote_ts: %" GST_TIME_FORMAT
" delta_ts: %" GST_STIME_FORMAT
" status: %u", pkt->seqnum,
GST_TIME_ARGS (pkt->remote_ts), GST_STIME_ARGS (delta_ts),
pkt->status);
}
if (first_sent_pkt) {
SentPacket *found = NULL;
guint16 sent_idx = pkt->seqnum - first_sent_pkt->seqnum;
if (sent_idx < twcc->sent_packets->len)
found = &g_array_index (twcc->sent_packets, SentPacket, sent_idx);
if (found && found->seqnum == pkt->seqnum) {
if (GST_CLOCK_TIME_IS_VALID (found->socket_ts)) {
pkt->local_ts = found->socket_ts;
} else {
pkt->local_ts = found->ts;
}
pkt->size = found->size;
pkt->pt = found->pt;
GST_LOG ("matching pkt: #%u with local_ts: %" GST_TIME_FORMAT
" size: %u", pkt->seqnum, GST_TIME_ARGS (pkt->local_ts), pkt->size);
}
}
}
_prune_sent_packets (twcc, twcc_packets);
return twcc_packets;
}
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