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Add support for centralised timing, jitter calculation, probably not working, add an aging factor to dispersion, as per NTP. Check crudely for out of sequence packets.

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This commit is contained in:
Mike Brady
2014-08-24 16:23:12 +01:00
parent ac59141848
commit 7bf5d4d63f
2 changed files with 55 additions and 17 deletions
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rtp.c
+52 -17
View File
@@ -33,6 +33,8 @@
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include "common.h"
#include "player.h"
#include "rtp.h"
@@ -71,7 +73,8 @@ static int request_sent;
static uint8_t time_ping_count;
struct time_ping_record time_pings[time_ping_history];
static struct timespec dtt; // dangerous -- this assumes that there will never be two timing request in flight at the same time
//static struct timespec dtt; // dangerous -- this assumes that there will never be two timing request in flight at the same time
static uint64_t departure_time; // dangerous -- this assumes that there will never be two timing request in flight at the same time
static pthread_mutex_t reference_time_mutex = PTHREAD_MUTEX_INITIALIZER;
@@ -79,6 +82,8 @@ uint64_t static local_to_remote_time_difference; // used to switch between local
static void *rtp_audio_receiver(void *arg) {
// we inherit the signal mask (SIGUSR1)
int32_t last_seqno = -1;
uint8_t packet[2048], *pktp;
ssize_t nread;
@@ -98,6 +103,16 @@ static void *rtp_audio_receiver(void *arg) {
plen -= 4;
}
seq_t seqno = ntohs(*(unsigned short *)(pktp+2));
// increment last_seqno and see if it's the same as the incoming seqno
if (last_seqno==-1)
last_seqno=seqno;
else {
last_seqno = (last_seqno+1)&0xffff;
if (seqno!=last_seqno)
debug(2,"RTP: Packets out of sequence: expected: %d, got %d.",last_seqno,seqno);
last_seqno=seqno; // reset warning...
}
uint32_t timestamp = ntohl(*(unsigned long *)(pktp+4));
//if (packet[1]&0x10)
@@ -138,8 +153,9 @@ static void *rtp_control_receiver(void *arg) {
if (please_shutdown)
break;
nread = recv(control_socket, packet, sizeof(packet), 0);
clock_gettime(CLOCK_MONOTONIC,&tn);
local_time_now=((uint64_t)tn.tv_sec<<32)+((uint64_t)tn.tv_nsec<<32)/1000000000;
local_time_now=get_absolute_time_in_ns();
// clock_gettime(CLOCK_MONOTONIC,&tn);
// local_time_now=((uint64_t)tn.tv_sec<<32)+((uint64_t)tn.tv_nsec<<32)/1000000000;
if (nread < 0)
break;
@@ -175,7 +191,8 @@ static void *rtp_control_receiver(void *arg) {
pthread_mutex_lock(&reference_time_mutex);
reference_timestamp_time = remote_time_of_sync-local_to_remote_time_difference;
reference_timestamp = sync_rtp_timestamp;
pthread_mutex_unlock(&reference_time_mutex);
pthread_mutex_unlock(&reference_time_mutex);
// debug(1,"New Reference timestamp and timestamp time...");
// get estimated remote time now
remote_time_now = local_time_now+local_to_remote_time_difference;
@@ -205,8 +222,6 @@ static void *rtp_timing_sender(void *arg) {
uint64_t request_number=0;
debug(1, "Timing requester startup.");
struct timing_request req; // *not* a standard RTCP NACK
req.leader = 0x80;
@@ -229,7 +244,8 @@ static void *rtp_timing_sender(void *arg) {
req.filler = 0;
req.origin = req.receive = req.transmit=0;
clock_gettime(CLOCK_MONOTONIC,&dtt);
// clock_gettime(CLOCK_MONOTONIC,&dtt);
departure_time=get_absolute_time_in_ns();
sendto(timing_socket, &req, sizeof(req), 0, (struct sockaddr*)&rtp_client_timing_socket, sizeof(rtp_client_timing_socket));
request_number++;
if (request_number<=4)
@@ -247,14 +263,17 @@ static void *rtp_timing_receiver(void *arg) {
ssize_t nread;
pthread_t timer_requester;
pthread_create(&timer_requester, NULL, &rtp_timing_sender, NULL);
struct timespec att;
uint64_t distant_receive_time,distant_transmit_time,arrival_time,departure_time,return_time,transit_time,processing_time;
local_to_remote_time_difference=0;
// struct timespec att;
uint64_t distant_receive_time,distant_transmit_time,arrival_time,return_time,transit_time,processing_time;
local_to_remote_time_jitters = 0;
local_to_remote_time_jitters_count = 0;
uint64_t l2rtd=0;
while (1) {
if (please_shutdown)
break;
nread = recv(timing_socket, packet, sizeof(packet), 0);
clock_gettime(CLOCK_MONOTONIC,&att);
arrival_time=get_absolute_time_in_ns();
// clock_gettime(CLOCK_MONOTONIC,&att);
if (nread < 0)
break;
@@ -274,8 +293,8 @@ static void *rtp_timing_receiver(void *arg) {
//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;
//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-departure_time;
@@ -300,6 +319,7 @@ static void *rtp_timing_receiver(void *arg) {
unsigned int cc;
for (cc=time_ping_history-1;cc>0;cc--) {
time_pings[cc]=time_pings[cc-1];
time_pings[cc].dispersion = (time_pings[cc].dispersion*133)/100; // make the dispersions 'age' by this rational factor
}
time_pings[0].local_to_remote_difference = local_time_by_remote_clock-arrival_time;
time_pings[0].dispersion = return_time;
@@ -308,14 +328,29 @@ static void *rtp_timing_receiver(void *arg) {
// now pick the timestamp with the lowest dispersion
local_to_remote_time_difference = time_pings[0].local_to_remote_difference;
uint64_t l2rtd = time_pings[0].local_to_remote_difference;
uint64_t tld = time_pings[0].dispersion;
for (cc=1;cc<time_ping_count;cc++)
if (time_pings[cc].dispersion<tld) {
local_to_remote_time_difference=time_pings[cc].local_to_remote_difference;
l2rtd=time_pings[cc].local_to_remote_difference;
tld=time_pings[cc].dispersion;
}
// rtus = (tld*1000000)>>32; debug(1,"Choosing time difference with dispersion of %lld us.",rtus);
int64_t ji;
if (time_ping_count>1) {
if (l2rtd>local_to_remote_time_difference) {
local_to_remote_time_jitters=local_to_remote_time_jitters+l2rtd-local_to_remote_time_difference;
ji = l2rtd-local_to_remote_time_difference;
} else {
local_to_remote_time_jitters=local_to_remote_time_jitters+local_to_remote_time_difference-l2rtd;
ji = - (local_to_remote_time_difference-l2rtd);
}
local_to_remote_time_jitters_count+=1;
}
// int64_t rtus = (tld*1000000)>>32; int64_t ji = ((local_to_remote_time_jitters/local_to_remote_time_jitters_count)*1000000)>>32; debug(1,"Choosing time difference with dispersion of %lld us with jitter of %lld",rtus,ji);
// int64_t rtus = (tld*1000000)>>32; ji = (ji*1000000)>>32; debug(1,"Choosing time difference with dispersion of %lld us with jitter of %lld us",rtus,ji);
local_to_remote_time_difference=l2rtd;
} else {
@@ -416,7 +451,7 @@ void rtp_setup(SOCKADDR *remote, int cport, int tport, int *lsport, int *lcport,
}
// now, we open three sockets -- one for the audio stream, one for the timing and one for the control
// bind to an available port
*lsport = bind_port(remote,&audio_socket,0);
*lcport = bind_port(remote,&control_socket,0);
*ltport = bind_port(remote,&timing_socket,0);
rtp.h
+3
View File
@@ -10,4 +10,7 @@ void rtp_request_resend(seq_t first, seq_t last);
void get_reference_timestamp_stuff(uint32_t *timestamp,uint64_t *timestamp_time);
void clear_reference_timestamp(void);
uint64_t static local_to_remote_time_jitters;
uint64_t static local_to_remote_time_jitters_count;
#endif // _RTP_H