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shairport-sync/rtp.c
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Mike Brady ccc4fe09af Tidy up the formats.
2018-11-20 22:56:53 +00:00

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/*
* Apple RTP protocol handler. This file is part of Shairport.
* Copyright (c) James Laird 2013
* Copyright (c) Mike Brady 2014 -- 2018
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "rtp.h"
#include "common.h"
#include "player.h"
#include "rtsp.h"
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <math.h>
#include <memory.h>
#include <netdb.h>
#include <netinet/in.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
uint64_t local_to_remote_time_jitter;
uint64_t local_to_remote_time_jitter_count;
void rtp_initialise(rtsp_conn_info *conn) {
conn->rtp_time_of_last_resend_request_error_fp = 0;
conn->rtp_running = 0;
// initialise the timer mutex
int rc = pthread_mutex_init(&conn->reference_time_mutex, NULL);
if (rc)
debug(1, "Error initialising reference_time_mutex.");
}
void rtp_terminate(rtsp_conn_info *conn) {
// destroy the timer mutex
int rc = pthread_mutex_destroy(&conn->reference_time_mutex);
if (rc)
debug(1, "Error destroying reference_time_mutex variable.");
}
uint64_t local_to_remote_time_difference_now(rtsp_conn_info *conn) {
// this is an attempt to compensate for clock drift since the last time ping that was used
// so, if we have a non-zero clock drift, we will calculate the drift there would
// be from the time of the last time ping
uint64_t local_time_now_fp = get_absolute_time_in_fp();
uint64_t time_since_last_local_to_remote_time_difference_measurement =
local_time_now_fp - conn->local_to_remote_time_difference_measurement_time;
uint64_t remote_time_since_last_local_to_remote_time_difference_measurement =
(uint64_t)(conn->local_to_remote_time_gradient *
time_since_last_local_to_remote_time_difference_measurement);
double drift;
if (remote_time_since_last_local_to_remote_time_difference_measurement >=
time_since_last_local_to_remote_time_difference_measurement)
drift = (1.0 * (remote_time_since_last_local_to_remote_time_difference_measurement -
time_since_last_local_to_remote_time_difference_measurement)) /
(uint64_t)0x100000000;
else
drift = -((1.0 * (time_since_last_local_to_remote_time_difference_measurement -
remote_time_since_last_local_to_remote_time_difference_measurement)) /
(uint64_t)0x100000000);
// double interval_ms =
// 1.0*(((time_since_last_local_to_remote_time_difference_measurement)*1000)>>32);
// debug(1,"Measurement drift is %.2f microseconds (0x%" PRIx64 " in 64-bit fp) over %.2f
// milliseconds with drift of %.2f
// ppm.",drift*1000000,(uint64_t)(drift*(uint64_t)0x100000000),interval_ms,(1.0-conn->local_to_remote_time_gradient)*1000000);
// return conn->local_to_remote_time_difference + (uint64_t)(drift*(uint64_t 0x100000000));
return conn->local_to_remote_time_difference + (uint64_t)(drift * (uint64_t)0x100000000);
}
void rtp_audio_receiver_cleanup_handler(void *arg) {
debug(3, "Audio Receiver Cleanup.");
rtsp_conn_info *conn = (rtsp_conn_info *)arg;
debug(1, "shutdown audio socket.");
shutdown(conn->audio_socket, SHUT_RDWR);
debug(1, "close audio socket.");
close(conn->audio_socket);
debug(3, "Audio Receiver Cleanup Successful.");
}
void *rtp_audio_receiver(void *arg) {
pthread_cleanup_push(rtp_audio_receiver_cleanup_handler, arg);
rtsp_conn_info *conn = (rtsp_conn_info *)arg;
int32_t last_seqno = -1;
uint8_t packet[2048], *pktp;
uint64_t time_of_previous_packet_fp = 0;
float longest_packet_time_interval_us = 0.0;
// mean and variance calculations from "online_variance" algorithm at
// https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Online_algorithm
int32_t stat_n = 0;
float stat_mean = 0.0;
float stat_M2 = 0.0;
ssize_t nread;
while (1) {
nread = recv(conn->audio_socket, packet, sizeof(packet), 0);
uint64_t local_time_now_fp = get_absolute_time_in_fp();
if (time_of_previous_packet_fp) {
float time_interval_us =
(((local_time_now_fp - time_of_previous_packet_fp) * 1000000) >> 32) * 1.0;
time_of_previous_packet_fp = local_time_now_fp;
if (time_interval_us > longest_packet_time_interval_us)
longest_packet_time_interval_us = time_interval_us;
stat_n += 1;
float stat_delta = time_interval_us - stat_mean;
stat_mean += stat_delta / stat_n;
stat_M2 += stat_delta * (time_interval_us - stat_mean);
if (stat_n % 2500 == 0) {
debug(2, "Packet reception interval stats: mean, standard deviation and max for the last "
"2,500 packets in microseconds: %10.1f, %10.1f, %10.1f.",
stat_mean, sqrtf(stat_M2 / (stat_n - 1)), longest_packet_time_interval_us);
stat_n = 0;
stat_mean = 0.0;
stat_M2 = 0.0;
time_of_previous_packet_fp = 0;
longest_packet_time_interval_us = 0.0;
}
} else {
time_of_previous_packet_fp = local_time_now_fp;
}
if (nread >= 0) {
ssize_t plen = nread;
uint8_t type = packet[1] & ~0x80;
if (type == 0x60 || type == 0x56) { // audio data / resend
pktp = packet;
if (type == 0x56) {
pktp += 4;
plen -= 4;
}
seq_t seqno = ntohs(*(uint16_t *)(pktp + 2));
// increment last_seqno and see if it's the same as the incoming seqno
if (type == 0x60) { // regular audio data
if (last_seqno == -1)
last_seqno = seqno;
else {
last_seqno = (last_seqno + 1) & 0xffff;
// if (seqno != last_seqno)
// debug(3, "RTP: Packets out of sequence: expected: %d, got %d.", last_seqno, seqno);
last_seqno = seqno; // reset warning...
}
} else {
debug(3, "Audio Receiver -- Retransmitted Audio Data Packet %u received.", seqno);
}
uint32_t actual_timestamp = ntohl(*(uint32_t *)(pktp + 4));
// if (packet[1]&0x10)
// debug(1,"Audio packet Extension bit set.");
pktp += 12;
plen -= 12;
// check if packet contains enough content to be reasonable
if (plen >= 16) {
if ((config.diagnostic_drop_packet_fraction == 0.0) ||
(drand48() > config.diagnostic_drop_packet_fraction))
player_put_packet(seqno, actual_timestamp, pktp, plen, conn);
else
debug(3, "Dropping audio packet %u to simulate a bad connection.", seqno);
continue;
}
if (type == 0x56 && seqno == 0) {
debug(2, "resend-related request packet received, ignoring.");
continue;
}
debug(1, "Audio receiver -- Unknown RTP packet of type 0x%02X length %d seqno %d", type,
nread, seqno);
}
warn("Audio receiver -- Unknown RTP packet of type 0x%02X length %d.", type, nread);
} else {
debug(1, "Error receiving an audio packet.");
}
}
/*
debug(3, "Audio receiver -- Server RTP thread interrupted. terminating.");
close(conn->audio_socket);
*/
debug(1, "Audio receiver thread \"normal\" exit -- this can't happen. Hah!");
pthread_cleanup_pop(0); // don't execute anything here.
debug(2, "Audio receiver thread exit.");
pthread_exit(NULL);
}
void rtp_control_handler_cleanup_handler(void *arg) {
debug(3, "Control Receiver Cleanup.");
rtsp_conn_info *conn = (rtsp_conn_info *)arg;
debug(1, "shutdown control socket.");
shutdown(conn->control_socket, SHUT_RDWR);
debug(1, "close control socket.");
close(conn->control_socket);
debug(3, "Control Receiver Cleanup Successful.");
}
void *rtp_control_receiver(void *arg) {
pthread_cleanup_push(rtp_control_handler_cleanup_handler, arg);
rtsp_conn_info *conn = (rtsp_conn_info *)arg;
conn->reference_timestamp = 0; // nothing valid received yet
uint8_t packet[2048], *pktp;
// struct timespec tn;
uint64_t remote_time_of_sync;
uint32_t sync_rtp_timestamp;
ssize_t nread;
while (1) {
nread = recv(conn->control_socket, packet, sizeof(packet), 0);
// local_time_now = get_absolute_time_in_fp();
// clock_gettime(CLOCK_MONOTONIC,&tn);
// local_time_now=((uint64_t)tn.tv_sec<<32)+((uint64_t)tn.tv_nsec<<32)/1000000000;
if (nread >= 0) {
if ((config.diagnostic_drop_packet_fraction == 0.0) ||
(drand48() > config.diagnostic_drop_packet_fraction)) {
ssize_t plen = nread;
if (packet[1] == 0xd4) { // sync data
/*
// the following stanza is for debugging only -- normally commented out.
{
char obf[4096];
char *obfp = obf;
int obfc;
for (obfc = 0; obfc < plen; obfc++) {
snprintf(obfp, 3, "%02X", packet[obfc]);
obfp += 2;
};
*obfp = 0;
// get raw timestamp information
// I think that a good way to understand these timestamps is that
// (1) the rtlt below is the timestamp of the frame that should be playing at the
// client-time specified in the packet if there was no delay
// and (2) that the rt below is the timestamp of the frame that should be playing
// at the client-time specified in the packet on this device taking account of
// the delay
// Thus, (3) the latency can be calculated by subtracting the second from the
// first.
// There must be more to it -- there something missing.
// In addition, it seems that if the value of the short represented by the second
// pair of bytes in the packet is 7
// then an extra time lag is expected to be added, presumably by
// the AirPort Express.
// Best guess is that this delay is 11,025 frames.
// uint32_t rtlt = nctohl(&packet[4]); // raw timestamp less latency
// uint32_t rt = nctohl(&packet[16]); // raw timestamp
// uint32_t fl = nctohs(&packet[2]); //
// debug(1,"Sync Packet of %d bytes received: \"%s\", flags: %d, timestamps %u and
%u,
giving a latency of %d frames.",plen,obf,fl,rt,rtlt,rt-rtlt);
// debug(1,"Monotonic timestamps are: %" PRId64 " and %" PRId64 "
respectively.",monotonic_timestamp(rt, conn),monotonic_timestamp(rtlt, conn));
}
*/
if (conn->local_to_remote_time_difference) { // need a time packet to be interchanged
// first...
remote_time_of_sync = (uint64_t)nctohl(&packet[8]) << 32;
remote_time_of_sync += nctohl(&packet[12]);
// debug(1,"Remote Sync Time: %0llx.",remote_time_of_sync);
sync_rtp_timestamp = nctohl(&packet[16]);
uint32_t rtp_timestamp_less_latency = nctohl(&packet[4]);
// debug(1,"Sync timestamp is %u.",ntohl(*((uint32_t *)&packet[16])));
if (config.userSuppliedLatency) {
if (config.userSuppliedLatency != conn->latency) {
debug(1, "Using the user-supplied latency: %" PRIu32 ".",
config.userSuppliedLatency);
}
conn->latency = config.userSuppliedLatency;
} else {
// It seems that the second pair of bytes in the packet indicate whether a fixed
// delay of 11,025 frames should be added -- iTunes set this field to 7 and
// AirPlay sets it to 4.
// However, on older versions of AirPlay, the 11,025 frames seem to be necessary too
// The value of 11,025 (0.25 seconds) is a guess based on the "Audio-Latency"
// parameter
// returned by an AE.
// Sigh, it would be nice to have a published protocol...
uint16_t flags = nctohs(&packet[2]);
uint32_t la = sync_rtp_timestamp - rtp_timestamp_less_latency; // note, this might
// loop around in
// modulo. Not sure if
// you'll get an error!
// debug(3, "Latency derived just from the sync packet is %" PRIu32 " frames.", la);
if ((flags == 7) || ((conn->AirPlayVersion > 0) && (conn->AirPlayVersion <= 353)) ||
((conn->AirPlayVersion > 0) && (conn->AirPlayVersion >= 371))) {
la += config.fixedLatencyOffset;
// debug(3, "A fixed latency offset of %d frames has been added, giving a latency of
// "
// "%" PRId64
// " frames with flags: %d and AirPlay version %d (triggers if 353 or
// less).",
// config.fixedLatencyOffset, la, flags, conn->AirPlayVersion);
}
if ((conn->maximum_latency) && (conn->maximum_latency < la))
la = conn->maximum_latency;
if ((conn->minimum_latency) && (conn->minimum_latency > la))
la = conn->minimum_latency;
const uint32_t max_frames = ((3 * BUFFER_FRAMES * 352) / 4) - 11025;
if (la > max_frames) {
warn("An out-of-range latency request of %" PRIu32
" frames was ignored. Must be %" PRIu32
" frames or less (44,100 frames per second). "
"Latency remains at %" PRIu32 " frames.",
la, max_frames, conn->latency);
} else {
if (la != conn->latency) {
conn->latency = la;
debug(3, "New latency detected: %" PRIu32 ", sync latency: %" PRIu32
", minimum latency: %" PRIu32 ", maximum "
"latency: %" PRIu32 ", fixed offset: %" PRIu32 ".",
la, sync_rtp_timestamp - rtp_timestamp_less_latency, conn->minimum_latency,
conn->maximum_latency, config.fixedLatencyOffset);
}
}
}
debug_mutex_lock(&conn->reference_time_mutex, 1000, 1);
if (conn->packet_stream_established) {
if (conn->initial_reference_time == 0) {
conn->initial_reference_time = remote_time_of_sync;
conn->initial_reference_timestamp = sync_rtp_timestamp;
} else {
uint64_t remote_frame_time_interval =
conn->remote_reference_timestamp_time -
conn->initial_reference_time; // here, this should never be zero
if (remote_frame_time_interval) {
conn->remote_frame_rate =
(1.0 * (conn->reference_timestamp - conn->initial_reference_timestamp)) /
remote_frame_time_interval; // an IEEE double calculation with a 32-bit
// numerator and 64-bit denominator
// integers
conn->remote_frame_rate = conn->remote_frame_rate *
(uint64_t)0x100000000; // this should just change the
// [binary] exponent in the IEEE
// FP representation; the
// mantissa should be unaffected.
} else {
conn->remote_frame_rate = 0.0; // use as a flag.
}
}
}
// this is for debugging
uint64_t old_remote_reference_time = conn->remote_reference_timestamp_time;
uint32_t old_reference_timestamp = conn->reference_timestamp;
// int64_t old_latency_delayed_timestamp = conn->latency_delayed_timestamp;
conn->remote_reference_timestamp_time = remote_time_of_sync;
// conn->reference_timestamp_time =
// remote_time_of_sync - local_to_remote_time_difference_now(conn);
conn->reference_timestamp = sync_rtp_timestamp;
conn->latency_delayed_timestamp = rtp_timestamp_less_latency;
debug_mutex_unlock(&conn->reference_time_mutex, 3);
conn->reference_to_previous_time_difference =
remote_time_of_sync - old_remote_reference_time;
if (old_reference_timestamp == 0)
conn->reference_to_previous_frame_difference = 0;
else
conn->reference_to_previous_frame_difference =
sync_rtp_timestamp - old_reference_timestamp;
// int64_t delayed_frame_difference = rtp_timestamp_less_latency -
// old_latency_delayed_timestamp;
/*
if (old_remote_reference_time)
debug(1,"Time difference: %" PRIu64 " reference and delayed frame differences: %"
PRId64 " and %" PRId64 ", giving rates _at source!!_ of %f and %f respectively.",
(conn->reference_to_previous_time_difference*1000000)>>32,conn->reference_to_previous_frame_difference,delayed_frame_difference,
(1.0*(conn->reference_to_previous_frame_difference*10000000))/((conn->reference_to_previous_time_difference*10000000)>>32),(1.0*(delayed_frame_difference*10000000))/((conn->reference_to_previous_time_difference*10000000)>>32));
else
debug(1,"First sync received");
*/
// debug(1,"New Reference timestamp and timestamp time...");
// get estimated remote time now
// remote_time_now = local_time_now + local_to_remote_time_difference;
// debug(1,"Sync Time is %lld us late (remote
// times).",((remote_time_now-remote_time_of_sync)*1000000)>>32);
// debug(1,"Sync Time is %lld us late (local
// times).",((local_time_now-reference_timestamp_time)*1000000)>>32);
} else {
debug(2, "Sync packet received before we got a timing packet back.");
}
} else if (packet[1] == 0xd6) { // resent audio data in the control path -- whaale only?
pktp = packet + 4;
plen -= 4;
seq_t seqno = ntohs(*(uint16_t *)(pktp + 2));
debug(3, "Control Receiver -- Retransmitted Audio Data Packet %u received.", seqno);
uint32_t actual_timestamp = ntohl(*(uint32_t *)(pktp + 4));
pktp += 12;
plen -= 12;
// check if packet contains enough content to be reasonable
if (plen >= 16) {
player_put_packet(seqno, actual_timestamp, pktp, plen, conn);
continue;
} else {
debug(3, "Too-short retransmitted audio packet received in control port, ignored.");
}
} else
debug(1, "Control Receiver -- Unknown RTP packet of type 0x%02X length %d, ignored.",
packet[1], nread);
} else {
debug(3, "Control Receiver -- dropping a packet to simulate a bad network.");
}
} else {
debug(1, "Control Receiver -- error receiving a packet.");
}
}
debug(1, "Control RTP thread \"normal\" exit -- this can't happen. Hah!");
pthread_cleanup_pop(0); // don't execute anything here.
debug(2, "Control RTP thread exit.");
pthread_exit(NULL);
}
void *rtp_timing_sender(void *arg) {
rtsp_conn_info *conn = (rtsp_conn_info *)arg;
struct timing_request {
char leader;
char type;
uint16_t seqno;
uint32_t filler;
uint64_t origin, receive, transmit;
};
uint64_t request_number = 0;
struct timing_request req; // *not* a standard RTCP NACK
req.leader = 0x80;
req.type = 0xd2; // Timing request
req.filler = 0;
req.seqno = htons(7);
conn->time_ping_count = 0;
while (1) {
// debug(1,"Send a timing request");
if (!conn->rtp_running)
debug(1, "rtp_timing_sender called without active stream in RTSP conversation thread %d!",
conn->connection_number);
// debug(1, "Requesting ntp timestamp exchange.");
req.filler = 0;
req.origin = req.receive = req.transmit = 0;
// clock_gettime(CLOCK_MONOTONIC,&dtt);
conn->departure_time = get_absolute_time_in_fp();
socklen_t msgsize = sizeof(struct sockaddr_in);
#ifdef AF_INET6
if (conn->rtp_client_timing_socket.SAFAMILY == AF_INET6) {
msgsize = sizeof(struct sockaddr_in6);
}
#endif
if ((config.diagnostic_drop_packet_fraction == 0.0) ||
(drand48() > config.diagnostic_drop_packet_fraction)) {
if (sendto(conn->timing_socket, &req, sizeof(req), 0,
(struct sockaddr *)&conn->rtp_client_timing_socket, msgsize) == -1) {
char em[1024];
strerror_r(errno, em, sizeof(em));
debug(1, "Error %d using send-to to the timing socket: \"%s\".", errno, em);
}
} else {
debug(3, "Timing Sender Thread -- dropping outgoing packet to simulate bad network.");
}
request_number++;
if (request_number <= 4)
usleep(500000); // these are thread cancellation points
else
usleep(3000000);
}
debug(3, "rtp_timing_sender thread interrupted. This should never happen.");
pthread_exit(NULL);
}
void rtp_timing_receiver_cleanup_handler(void *arg) {
debug(3, "Timing Receiver Cleanup.");
rtsp_conn_info *conn = (rtsp_conn_info *)arg;
pthread_cancel(conn->timer_requester);
pthread_join(conn->timer_requester, NULL);
debug(1, "shutdown timing socket.");
shutdown(conn->timing_socket, SHUT_RDWR);
debug(1, "close timing socket.");
close(conn->timing_socket);
debug(3, "Timing Receiver Cleanup Successful.");
}
void *rtp_timing_receiver(void *arg) {
pthread_cleanup_push(rtp_timing_receiver_cleanup_handler, arg);
rtsp_conn_info *conn = (rtsp_conn_info *)arg;
uint8_t packet[2048];
ssize_t nread;
pthread_create(&conn->timer_requester, NULL, &rtp_timing_sender, arg);
// struct timespec att;
uint64_t distant_receive_time, distant_transmit_time, arrival_time, return_time;
local_to_remote_time_jitter = 0;
local_to_remote_time_jitter_count = 0;
// uint64_t first_remote_time = 0;
// uint64_t first_local_time = 0;
uint64_t first_local_to_remote_time_difference = 0;
// uint64_t first_local_to_remote_time_difference_time;
// uint64_t l2rtd = 0;
int sequence_number = 0;
// for getting mean and sd of return times
int32_t stat_n = 0;
double stat_mean = 0.0;
double stat_M2 = 0.0;
while (1) {
nread = recv(conn->timing_socket, packet, sizeof(packet), 0);
if (nread >= 0) {
if ((config.diagnostic_drop_packet_fraction == 0.0) ||
(drand48() > config.diagnostic_drop_packet_fraction)) {
arrival_time = get_absolute_time_in_fp();
// ssize_t plen = nread;
// debug(1,"Packet Received on Timing Port.");
if (packet[1] == 0xd3) { // timing reply
/*
char obf[4096];
char *obfp = obf;
int obfc;
for (obfc=0;obfc<plen;obfc++) {
snprintf(obfp, 3, "%02X", packet[obfc]);
obfp+=2;
};
*obfp=0;
//debug(1,"Timing Packet Received: \"%s\"",obf);
*/
// arrival_time = ((uint64_t)att.tv_sec<<32)+((uint64_t)att.tv_nsec<<32)/1000000000;
// departure_time = ((uint64_t)dtt.tv_sec<<32)+((uint64_t)dtt.tv_nsec<<32)/1000000000;
return_time = arrival_time - conn->departure_time;
// uint64_t rtus = (return_time * 1000000) >> 32;
if (((return_time * 1000000) >> 32) < 300000) {
// debug(2,"Synchronisation ping return time is %f milliseconds.",(rtus*1.0)/1000);
// distant_receive_time =
// ((uint64_t)ntohl(*((uint32_t*)&packet[16])))<<32+ntohl(*((uint32_t*)&packet[20]));
distant_receive_time = (uint64_t)nctohl(&packet[16]) << 32;
distant_receive_time += nctohl(&packet[20]);
// distant_transmit_time =
// ((uint64_t)ntohl(*((uint32_t*)&packet[24])))<<32+ntohl(*((uint32_t*)&packet[28]));
distant_transmit_time = (uint64_t)nctohl(&packet[24]) << 32;
distant_transmit_time += nctohl(&packet[28]);
uint64_t remote_processing_time = 0;
if (distant_transmit_time >= distant_receive_time)
remote_processing_time = distant_transmit_time - distant_receive_time;
else {
debug(1, "Yikes: distant_transmit_time is before distant_receive_time; remote "
"processing time set to zero.");
}
// debug(1,"Return trip time: %" PRIu64 " uS, remote processing time: %" PRIu64 "
// uS.",(return_time*1000000)>>32,(remote_processing_time*1000000)>>32);
uint64_t local_time_by_remote_clock = distant_transmit_time + return_time / 2;
// remove the remote processing time from the record of the return time, as long at the
// processing time looks sensible.
if (remote_processing_time < return_time)
return_time -= remote_processing_time;
else
debug(1, "Remote processing time greater than return time -- ignored.");
int cc;
for (cc = time_ping_history - 1; cc > 0; cc--) {
conn->time_pings[cc] = conn->time_pings[cc - 1];
// if ((conn->time_ping_count) && (conn->time_ping_count < 10))
// conn->time_pings[cc].dispersion =
// conn->time_pings[cc].dispersion * pow(2.14,
// 1.0/conn->time_ping_count);
conn->time_pings[cc].dispersion =
(conn->time_pings[cc].dispersion * 110) /
100; // make the dispersions 'age' by this rational factor
}
// these are used for doing a least squares calculation to get the drift
conn->time_pings[0].local_time = arrival_time;
conn->time_pings[0].remote_time = distant_transmit_time;
conn->time_pings[0].sequence_number = sequence_number++;
conn->time_pings[0].chosen = 0;
conn->time_pings[0].local_to_remote_difference =
local_time_by_remote_clock - arrival_time;
conn->time_pings[0].dispersion = return_time;
if (conn->time_ping_count < time_ping_history)
conn->time_ping_count++;
// here, calculate the mean and standard deviation of the return times
// mean and variance calculations from "online_variance" algorithm at
// https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Online_algorithm
double rtfus = 1.0 * ((return_time * 1000000) >> 32);
stat_n += 1;
double stat_delta = rtfus - stat_mean;
stat_mean += stat_delta / stat_n;
stat_M2 += stat_delta * (rtfus - stat_mean);
// debug(1, "Timing packet return time stats: current, mean and standard deviation over
// %d packets: %.1f, %.1f, %.1f (microseconds).",
// stat_n,rtfus,stat_mean, sqrtf(stat_M2 / (stat_n - 1)));
// here, pick the record with the least dispersion, and record that it's been chosen
// uint64_t local_time_chosen = arrival_time;
// uint64_t remote_time_chosen = distant_transmit_time;
// now pick the timestamp with the lowest dispersion
uint64_t l2rtd = conn->time_pings[0].local_to_remote_difference;
uint64_t lt = conn->time_pings[0].local_time;
uint64_t tld = conn->time_pings[0].dispersion;
int chosen = 0;
for (cc = 1; cc < conn->time_ping_count; cc++)
if (conn->time_pings[cc].dispersion < tld) {
chosen = cc;
l2rtd = conn->time_pings[cc].local_to_remote_difference;
lt = conn->time_pings[cc].local_time;
tld = conn->time_pings[cc].dispersion;
// local_time_chosen = conn->time_pings[cc].local_time;
// remote_time_chosen = conn->time_pings[cc].remote_time;
}
// debug(1,"Record %d has the lowest dispersion with %0.2f us
// dispersion.",chosen,1.0*((tld * 1000000) >> 32));
conn->time_pings[chosen].chosen = 1; // record the fact that it has been used for timing
/*
// calculate the jitter -- the absolute time between the current
local_to_remote_time_difference and the new one and add it to the total jitter count
int64_t ji;
int64_t ltd =0; // local time difference for the jitter
if (conn->time_ping_count > 1) {
if (l2rtd > conn->local_to_remote_time_difference) {
local_to_remote_time_jitter =
local_to_remote_time_jitter + l2rtd - conn->local_to_remote_time_difference;
ji = l2rtd - conn->local_to_remote_time_difference; // this is the difference
between the present local-to-remote-time-difference and the new one, i.e. the jitter
step
} else {
local_to_remote_time_jitter =
local_to_remote_time_jitter + conn->local_to_remote_time_difference - l2rtd;
ji = -(conn->local_to_remote_time_difference - l2rtd);
}
local_to_remote_time_jitter_count += 1;
}
if (conn->local_to_remote_time_difference_measurement_time < lt)
ltd = lt-conn->local_to_remote_time_difference_measurement_time;
else
ltd = -(conn->local_to_remote_time_difference_measurement_time-lt);
if (ltd) {
debug(1,"Jitter: %" PRId64 " microseconds in %" PRId64 " microseconds.", (ji *
(int64_t)1000000)>>32, (ltd * (int64_t)1000000)>>32);
debug(1,"Source clock to local clock drift: %.2f ppm.",((1.0*ji)/ltd)*1000000.0);
}
// uncomment below to print jitter between client's clock and our clock
if (ji) {
int64_t rtus = (tld*1000000)>>32;
debug(1,"Choosing time difference[%d] with dispersion of %" PRId64 " us with an
adjustment of %" PRId64 " us",chosen, rtus, (ji*1000000)>>32);
}
*/
conn->local_to_remote_time_difference =
l2rtd; // make this the new local-to-remote-time-difference
conn->local_to_remote_time_difference_measurement_time = lt; // done at this time.
if (first_local_to_remote_time_difference == 0) {
first_local_to_remote_time_difference = conn->local_to_remote_time_difference;
// first_local_to_remote_time_difference_time = get_absolute_time_in_fp();
}
// here, let's try to use the timing pings that were selected because of their short
// return times to
// estimate a figure for drift between the local clock (x) and the remote clock (y)
// if we plug in a local interval, we will get back what that is in remote time
// calculate the line of best fit for relating the local time and the remote time
// we will calculate the slope, which is the drift
// see https://www.varsitytutors.com/hotmath/hotmath_help/topics/line-of-best-fit
uint64_t y_bar = 0; // remote timestamp average
uint64_t x_bar = 0; // local timestamp average
int sample_count = 0;
// approximate time in seconds to let the system settle down
const int settling_time = 60;
// number of points to have for calculating a valid drift
const int sample_point_minimum = 8;
for (cc = 0; cc < conn->time_ping_count; cc++)
if ((conn->time_pings[cc].chosen) &&
(conn->time_pings[cc].sequence_number >
(settling_time / 3))) { // wait for a approximate settling time
y_bar += (conn->time_pings[cc].remote_time >>
12); // precision is down to 1/4th of a microsecond
x_bar += (conn->time_pings[cc].local_time >> 12);
sample_count++;
}
if (sample_count > sample_point_minimum) {
y_bar = y_bar / sample_count;
x_bar = x_bar / sample_count;
int64_t xid, yid;
int64_t mtl, mbl;
mtl = 0;
mbl = 0;
for (cc = 0; cc < conn->time_ping_count; cc++)
if ((conn->time_pings[cc].chosen) &&
(conn->time_pings[cc].sequence_number > (settling_time / 3))) {
uint64_t slt = conn->time_pings[cc].local_time >> 12;
if (slt > x_bar)
xid = slt - x_bar;
else
xid = -(x_bar - slt);
uint64_t srt = conn->time_pings[cc].remote_time >> 12;
if (srt > y_bar)
yid = srt - y_bar;
else
yid = -(y_bar - srt);
mtl = mtl + xid * yid;
mbl = mbl + xid * xid;
}
conn->local_to_remote_time_gradient_sample_count = sample_count;
conn->local_to_remote_time_gradient = (1.0 * mtl) / mbl;
} else {
conn->local_to_remote_time_gradient = 1.0;
}
// debug(1,"local to remote time gradient is %12.2f ppm, based on %d
// samples.",conn->local_to_remote_time_gradient*1000000,sample_count);
} else {
debug(2, "Time ping turnaround time: %lld us -- it looks like a timing ping was lost.",
(return_time * 1000000) >> 32);
}
} else {
debug(1, "Timing port -- Unknown RTP packet of type 0x%02X length %d.", packet[1], nread);
}
} else {
debug(3, "Timing Receiver Thread -- dropping incoming packet to simulate a bad network.");
}
} else {
debug(1, "Timing receiver -- error receiving a packet.");
}
}
debug(1, "Timing Receiver RTP thread \"normal\" exit -- this can't happen. Hah!");
pthread_cleanup_pop(0); // don't execute anything here.
debug(2, "Timing Receiver RTP thread exit.");
pthread_exit(NULL);
}
static uint16_t bind_port(int ip_family, const char *self_ip_address, uint32_t scope_id,
int *sock) {
// look for a port in the range, if any was specified.
uint16_t desired_port = config.udp_port_base;
int ret = 0;
int local_socket = socket(ip_family, SOCK_DGRAM, IPPROTO_UDP);
if (local_socket == -1)
die("Could not allocate a socket.");
SOCKADDR myaddr;
do {
memset(&myaddr, 0, sizeof(myaddr));
if (ip_family == AF_INET) {
struct sockaddr_in *sa = (struct sockaddr_in *)&myaddr;
sa->sin_family = AF_INET;
sa->sin_port = ntohs(desired_port);
inet_pton(AF_INET, self_ip_address, &(sa->sin_addr));
ret = bind(local_socket, (struct sockaddr *)sa, sizeof(struct sockaddr_in));
}
#ifdef AF_INET6
if (ip_family == AF_INET6) {
struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)&myaddr;
sa6->sin6_family = AF_INET6;
sa6->sin6_port = ntohs(desired_port);
inet_pton(AF_INET6, self_ip_address, &(sa6->sin6_addr));
sa6->sin6_scope_id = scope_id;
ret = bind(local_socket, (struct sockaddr *)sa6, sizeof(struct sockaddr_in6));
}
#endif
} while ((ret < 0) && (errno == EADDRINUSE) && (desired_port != 0) &&
(++desired_port < config.udp_port_base + config.udp_port_range));
// debug(1,"UDP port chosen: %d.",desired_port);
if (ret < 0) {
close(local_socket);
die("error: could not bind a UDP port! Check the udp_port_range is large enough (>= 10) or "
"check for restrictive firewall settings or a bad router!");
}
uint16_t sport;
SOCKADDR local;
socklen_t local_len = sizeof(local);
getsockname(local_socket, (struct sockaddr *)&local, &local_len);
#ifdef AF_INET6
if (local.SAFAMILY == AF_INET6) {
struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)&local;
sport = ntohs(sa6->sin6_port);
} else
#endif
{
struct sockaddr_in *sa = (struct sockaddr_in *)&local;
sport = ntohs(sa->sin_port);
}
*sock = local_socket;
return sport;
}
void rtp_setup(SOCKADDR *local, SOCKADDR *remote, uint16_t cport, uint16_t tport,
rtsp_conn_info *conn) {
// this gets the local and remote ip numbers (and ports used for the TCD stuff)
// we use the local stuff to specify the address we are coming from and
// we use the remote stuff to specify where we're goint to
if (conn->rtp_running)
warn("rtp_setup has been called with al already-active stream -- ignored. Possible duplicate "
"SETUP call?");
else {
debug(3, "rtp_setup: cport=%d tport=%d.", cport, tport);
// print out what we know about the client
void *client_addr = NULL, *self_addr = NULL;
// int client_port, self_port;
// char client_port_str[64];
// char self_addr_str[64];
conn->connection_ip_family =
remote->SAFAMILY; // keep information about the kind of ip of the client
#ifdef AF_INET6
if (conn->connection_ip_family == AF_INET6) {
struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)remote;
client_addr = &(sa6->sin6_addr);
// client_port = ntohs(sa6->sin6_port);
sa6 = (struct sockaddr_in6 *)local;
self_addr = &(sa6->sin6_addr);
// self_port = ntohs(sa6->sin6_port);
conn->self_scope_id = sa6->sin6_scope_id;
}
#endif
if (conn->connection_ip_family == AF_INET) {
struct sockaddr_in *sa4 = (struct sockaddr_in *)remote;
client_addr = &(sa4->sin_addr);
// client_port = ntohs(sa4->sin_port);
sa4 = (struct sockaddr_in *)local;
self_addr = &(sa4->sin_addr);
// self_port = ntohs(sa4->sin_port);
}
inet_ntop(conn->connection_ip_family, client_addr, conn->client_ip_string,
sizeof(conn->client_ip_string));
inet_ntop(conn->connection_ip_family, self_addr, conn->self_ip_string,
sizeof(conn->self_ip_string));
debug(2, "Connection %d: SETUP -- Connection from %s to self at %s.", conn->connection_number,
conn->client_ip_string, conn->self_ip_string);
// set up a the record of the remote's control socket
struct addrinfo hints;
struct addrinfo *servinfo;
memset(&conn->rtp_client_control_socket, 0, sizeof(conn->rtp_client_control_socket));
memset(&hints, 0, sizeof hints);
hints.ai_family = conn->connection_ip_family;
hints.ai_socktype = SOCK_DGRAM;
char portstr[20];
snprintf(portstr, 20, "%d", cport);
if (getaddrinfo(conn->client_ip_string, portstr, &hints, &servinfo) != 0)
die("Can't get address of client's control port");
#ifdef AF_INET6
if (servinfo->ai_family == AF_INET6) {
memcpy(&conn->rtp_client_control_socket, servinfo->ai_addr, sizeof(struct sockaddr_in6));
// ensure the scope id matches that of remote. this is needed for link-local addresses.
struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)&conn->rtp_client_control_socket;
sa6->sin6_scope_id = conn->self_scope_id;
} else
#endif
memcpy(&conn->rtp_client_control_socket, servinfo->ai_addr, sizeof(struct sockaddr_in));
freeaddrinfo(servinfo);
// set up a the record of the remote's timing socket
memset(&conn->rtp_client_timing_socket, 0, sizeof(conn->rtp_client_timing_socket));
memset(&hints, 0, sizeof hints);
hints.ai_family = conn->connection_ip_family;
hints.ai_socktype = SOCK_DGRAM;
snprintf(portstr, 20, "%d", tport);
if (getaddrinfo(conn->client_ip_string, portstr, &hints, &servinfo) != 0)
die("Can't get address of client's timing port");
#ifdef AF_INET6
if (servinfo->ai_family == AF_INET6) {
memcpy(&conn->rtp_client_timing_socket, servinfo->ai_addr, sizeof(struct sockaddr_in6));
// ensure the scope id matches that of remote. this is needed for link-local addresses.
struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)&conn->rtp_client_timing_socket;
sa6->sin6_scope_id = conn->self_scope_id;
} else
#endif
memcpy(&conn->rtp_client_timing_socket, servinfo->ai_addr, sizeof(struct sockaddr_in));
freeaddrinfo(servinfo);
// now, we open three sockets -- one for the audio stream, one for the timing and one for the
// control
conn->remote_control_port = cport;
conn->remote_timing_port = tport;
conn->local_control_port = bind_port(conn->connection_ip_family, conn->self_ip_string,
conn->self_scope_id, &conn->control_socket);
conn->local_timing_port = bind_port(conn->connection_ip_family, conn->self_ip_string,
conn->self_scope_id, &conn->timing_socket);
conn->local_audio_port = bind_port(conn->connection_ip_family, conn->self_ip_string,
conn->self_scope_id, &conn->audio_socket);
debug(3, "listening for audio, control and timing on ports %d, %d, %d.", conn->local_audio_port,
conn->local_control_port, conn->local_timing_port);
conn->reference_timestamp = 0;
// pthread_create(&rtp_audio_thread, NULL, &rtp_audio_receiver, NULL);
// pthread_create(&rtp_control_thread, NULL, &rtp_control_receiver, NULL);
// pthread_create(&rtp_timing_thread, NULL, &rtp_timing_receiver, NULL);
conn->request_sent = 0;
conn->rtp_running = 1;
#ifdef CONFIG_METADATA
send_ssnc_metadata('clip', strdup(conn->client_ip_string), strlen(conn->client_ip_string), 1);
send_ssnc_metadata('svip', strdup(conn->self_ip_string), strlen(conn->self_ip_string), 1);
#endif
}
}
void get_reference_timestamp_stuff(uint32_t *timestamp, uint64_t *timestamp_time,
uint64_t *remote_timestamp_time, rtsp_conn_info *conn) {
// types okay
debug_mutex_lock(&conn->reference_time_mutex, 1000, 1);
*timestamp = conn->reference_timestamp;
*remote_timestamp_time = conn->remote_reference_timestamp_time;
*timestamp_time =
conn->remote_reference_timestamp_time - local_to_remote_time_difference_now(conn);
// if ((*timestamp == 0) && (*timestamp_time == 0)) {
// debug(1,"Reference timestamp is invalid.");
//}
debug_mutex_unlock(&conn->reference_time_mutex, 3);
}
void clear_reference_timestamp(rtsp_conn_info *conn) {
debug_mutex_lock(&conn->reference_time_mutex, 1000, 1);
conn->reference_timestamp = 0;
conn->remote_reference_timestamp_time = 0;
debug_mutex_unlock(&conn->reference_time_mutex, 3);
}
int have_timestamp_timing_information(rtsp_conn_info *conn) {
if (conn->reference_timestamp == 0)
return 0;
else
return 1;
}
// set this to zero to use the rates supplied by the sources, which might not always be completely
// right...
const int use_nominal_rate = 0; // specify whether to use the nominal input rate, usually 44100 fps
int sanitised_source_rate_information(uint32_t *frames, uint64_t *time, rtsp_conn_info *conn) {
int result = 1;
uint32_t fs = conn->input_rate;
*frames = fs;
uint64_t one_fp = (uint64_t)(0x100000000); // one second in fp form
*time = one_fp;
if ((conn->packet_stream_established) && (conn->initial_reference_time) &&
(conn->initial_reference_timestamp)) {
// uint32_t local_frames = conn->reference_timestamp - conn->initial_reference_timestamp;
uint32_t local_frames =
modulo_32_offset(conn->initial_reference_timestamp, conn->reference_timestamp);
uint64_t local_time = conn->remote_reference_timestamp_time - conn->initial_reference_time;
if ((local_frames == 0) || (local_time == 0) || (use_nominal_rate)) {
result = 1;
} else {
double calculated_frame_rate = ((1.0 * local_frames) / local_time) * one_fp;
if (((calculated_frame_rate / conn->input_rate) > 1.002) ||
((calculated_frame_rate / conn->input_rate) < 0.998)) {
debug(1, "input frame rate out of bounds at %.2f fps.", calculated_frame_rate);
result = 1;
} else {
*frames = local_frames;
*time = local_time;
result = 0;
}
}
}
return result;
}
// the timestamp is a timestamp calculated at the input rate
// the reference timestamps are denominated in terms of the input rate
int frame_to_local_time(uint32_t timestamp, uint64_t *time, rtsp_conn_info *conn) {
debug_mutex_lock(&conn->reference_time_mutex, 1000, 1);
int result = 0;
uint64_t time_difference;
uint32_t frame_difference;
result = sanitised_source_rate_information(&frame_difference, &time_difference, conn);
uint64_t timestamp_interval_time;
uint64_t remote_time_of_timestamp;
uint32_t timestamp_interval = modulo_32_offset(conn->reference_timestamp, timestamp);
if (timestamp_interval <=
conn->input_rate * 3600) { // i.e. timestamp was really after the reference timestamp
timestamp_interval_time = (timestamp_interval * time_difference) /
frame_difference; // this is the nominal time, based on the
// fps specified between current and
// previous sync frame.
remote_time_of_timestamp = conn->remote_reference_timestamp_time +
timestamp_interval_time; // based on the reference timestamp time
// plus the time interval calculated based
// on the specified fps.
} else { // i.e. timestamp was actually before the reference timestamp
timestamp_interval =
modulo_32_offset(timestamp, conn->reference_timestamp); // fix the calculation
timestamp_interval_time = (timestamp_interval * time_difference) /
frame_difference; // this is the nominal time, based on the
// fps specified between current and
// previous sync frame.
remote_time_of_timestamp = conn->remote_reference_timestamp_time -
timestamp_interval_time; // based on the reference timestamp time
// plus the time interval calculated based
// on the specified fps.
}
*time = remote_time_of_timestamp - local_to_remote_time_difference_now(conn);
debug_mutex_unlock(&conn->reference_time_mutex, 3);
return result;
}
int local_time_to_frame(uint64_t time, uint32_t *frame, rtsp_conn_info *conn) {
debug_mutex_lock(&conn->reference_time_mutex, 1000, 1);
int result = 0;
uint64_t time_difference;
uint32_t frame_difference;
result = sanitised_source_rate_information(&frame_difference, &time_difference, conn);
// first, get from [local] time to remote time.
uint64_t remote_time = time + local_to_remote_time_difference_now(conn);
// next, get the remote time interval from the remote_time to the reference time
uint64_t time_interval;
// here, we calculate the time interval, in terms of remote time
uint64_t offset = modulo_64_offset(conn->remote_reference_timestamp_time, remote_time);
int reference_time_was_earlier = (offset <= (uint64_t)0x100000000 * 3600);
if (reference_time_was_earlier) // if we haven't had a reference within the last hour, it'll be
// taken as afterwards
time_interval = remote_time - conn->remote_reference_timestamp_time;
else
time_interval = conn->remote_reference_timestamp_time - remote_time;
// now, convert the remote time interval into frames using the frame rate we have observed or
// which has been nominated
uint32_t frame_interval = (time_interval * frame_difference) / time_difference;
if (reference_time_was_earlier) {
// debug(1,"Frame interval is %" PRId64 " frames.",frame_interval);
*frame = (conn->reference_timestamp + frame_interval);
} else {
// debug(1,"Frame interval is %" PRId64 " frames.",-frame_interval);
*frame = (conn->reference_timestamp - frame_interval);
}
debug_mutex_unlock(&conn->reference_time_mutex, 3);
return result;
}
void rtp_request_resend(seq_t first, uint32_t count, rtsp_conn_info *conn) {
if (conn->rtp_running) {
// if (!request_sent) {
// debug(2, "requesting resend of %d packets starting at %u.", count, first);
// request_sent = 1;
//}
char req[8]; // *not* a standard RTCP NACK
req[0] = 0x80;
req[1] = (char)0x55 | (char)0x80; // Apple 'resend'
*(unsigned short *)(req + 2) = htons(1); // our sequence number
*(unsigned short *)(req + 4) = htons(first); // missed seqnum
*(unsigned short *)(req + 6) = htons(count); // count
socklen_t msgsize = sizeof(struct sockaddr_in);
#ifdef AF_INET6
if (conn->rtp_client_control_socket.SAFAMILY == AF_INET6) {
msgsize = sizeof(struct sockaddr_in6);
}
#endif
uint64_t time_of_sending_fp = get_absolute_time_in_fp();
uint64_t resend_error_backoff_time = (uint64_t)1 << (32 - 4); // one sixteenth of a second
if ((conn->rtp_time_of_last_resend_request_error_fp == 0) ||
((time_of_sending_fp - conn->rtp_time_of_last_resend_request_error_fp) >
resend_error_backoff_time)) {
if ((config.diagnostic_drop_packet_fraction == 0.0) ||
(drand48() > config.diagnostic_drop_packet_fraction)) {
// put a time limit on the sendto
struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = 100000;
if (setsockopt(conn->control_socket, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout,
sizeof(timeout)) < 0)
debug(1, "Can't set timeout on resend request socket.");
if (sendto(conn->control_socket, req, sizeof(req), 0,
(struct sockaddr *)&conn->rtp_client_control_socket, msgsize) == -1) {
char em[1024];
strerror_r(errno, em, sizeof(em));
debug(1, "Error %d using sendto to an audio socket: \"%s\". Backing off for 1/16th of a "
"second.",
errno, em);
conn->rtp_time_of_last_resend_request_error_fp = time_of_sending_fp;
} else {
conn->rtp_time_of_last_resend_request_error_fp = 0;
}
} else {
debug(
3,
"Dropping resend request packet to simulate a bad network. Backing off for 1/16th of a "
"second.");
conn->rtp_time_of_last_resend_request_error_fp = time_of_sending_fp;
}
} else {
debug(3, "Backing off sending resend requests due to a previous send-to error");
}
} else {
// if (!request_sent) {
debug(2, "rtp_request_resend called without active stream!");
// request_sent = 1;
//}
}
}
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