qiurui
/
uvgrtp-base
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Use NTP to calculate RTP timestamps

This commit is contained in:
Aaro Altonen 2020-10-26 07:28:10 +02:00
parent 0102bb2801
commit 3195a271e9
3 changed files with 15 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/rtp.hh
View File

@ -42,7 +42,7 @@ namespace uvg_rtp {
uint8_t payload_;
uint32_t clock_rate_;
uint32_t wc_start_;
uint64_t wc_start_;
uvg_rtp::clock::hrc::hrc_t wc_start_2;
size_t sent_pkts_;

17
src/clock.cc
View File

@ -6,20 +6,23 @@
#endif
#include "clock.hh"
#include <stdio.h>
static const uint64_t EPOCH = 2208988800ULL;
static const uint64_t NTP_SCALE_FRAC = 4294967296ULL;
static inline uint32_t ntp_diff_ms(uint64_t t1, uint64_t t2)
{
uint32_t s_diff = (t1 >> 32) - (t2 >> 32);
uint32_t us_diff = (((t1 & 0xffffffff) - (t2 & 0xffffffff)) * 1000000UL) >> 32;
uint32_t s1 = (t1 >> 32) & 0xffffffff;
uint32_t s2 = (t2 >> 32) & 0xffffffff;
uint64_t us1 = ((t1 & 0xffffffff) * 1000000UL) / NTP_SCALE_FRAC;
uint64_t us2 = ((t2 & 0xffffffff) * 1000000UL) / NTP_SCALE_FRAC;
return s_diff / 1000 + (us_diff / 1000);
return (((s1 - s2) * 1000000) + ((us1 - us2))) / 1000;
}
uint64_t uvg_rtp::clock::ntp::now()
{
static const uint64_t EPOCH = 2208988800ULL;
static const uint64_t NTP_SCALE_FRAC = 4294967296ULL;
struct timeval tv;
#ifdef _WIN32
uvg_rtp::clock::gettimeofday(&tv, NULL);
@ -30,7 +33,7 @@ uint64_t uvg_rtp::clock::ntp::now()
uint64_t tv_ntp, tv_usecs;
tv_ntp = tv.tv_sec + EPOCH;
tv_usecs = (NTP_SCALE_FRAC * tv.tv_usec) / 1000000UL;
tv_usecs = (float)(NTP_SCALE_FRAC * tv.tv_usec) / (float)1000000UL;
return (tv_ntp << 32) | tv_usecs;
}

8
src/rtp.cc
View File

@ -90,10 +90,9 @@ void uvg_rtp::rtp::fill_header(uint8_t *buffer)
/* This is the first RTP message, get wall clock reading (t = 0)
* and generate random RTP timestamp for this reading */
if (wc_start_ == 0) {
if (!wc_start_) {
ts_ = uvg_rtp::random::generate_32();
wc_start_2 = uvg_rtp::clock::hrc::now();
wc_start_ = 1;
wc_start_ = uvg_rtp::clock::ntp::now();
}
buffer[0] = 2 << 6; // RTP version
@ -105,10 +104,11 @@ void uvg_rtp::rtp::fill_header(uint8_t *buffer)
if (timestamp_ == INVALID_TS) {
*(uint32_t *)&buffer[4] = htonl(
ts_
+ uvg_rtp::clock::hrc::diff_now(wc_start_2)
+ uvg_rtp::clock::ntp::diff_now(wc_start_)
* clock_rate_
/ 1000
);
} else {
*(uint32_t *)&buffer[4] = htonl(timestamp_);
}