rtcp.c

一个开源SIP协议栈

/* $Id: rtcp.c 974 2007-02-19 01:13:53Z bennylp $ */
/* 
 * Copyright (C) 2003-2007 Benny Prijono <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#include <pjmedia/rtcp.h>
#include <pjmedia/errno.h>
#include <pj/assert.h>
#include <pj/log.h>
#include <pj/os.h>
#include <pj/sock.h>
#include <pj/string.h>

#define THIS_FILE "rtcp.c"

#define RTCP_SR   200
#define RTCP_RR   201


#if PJ_HAS_HIGH_RES_TIMER==0
#   error "High resolution timer needs to be enabled"
#endif



#if 0
#   define TRACE_(x)	PJ_LOG(3,x)
#else
#   define TRACE_(x)	;
#endif


/*
 * Get NTP time.
 */
PJ_DEF(pj_status_t) pjmedia_rtcp_get_ntp_time(const pjmedia_rtcp_session *sess,
					      pjmedia_rtcp_ntp_rec *ntp)
{
/* Seconds between 1900-01-01 to 1970-01-01 */
#define JAN_1970  (2208988800UL)
    pj_timestamp ts;
    pj_status_t status;

    status = pj_get_timestamp(&ts);

    /* Fill up the high 32bit part */
    ntp->hi = (pj_uint32_t)((ts.u64 - sess->ts_base.u64) / sess->ts_freq.u64)
	      + sess->tv_base.sec + JAN_1970;

    /* Calculate seconds fractions */
    ts.u64 %= sess->ts_freq.u64;
    pj_assert(ts.u64 < sess->ts_freq.u64);
    ts.u64 = (ts.u64 << 32) / sess->ts_freq.u64;

    /* Fill up the low 32bit part */
    ntp->lo = ts.u32.lo;


#if (defined(PJ_WIN32) && PJ_WIN32!=0) || \
    (defined(PJ_WIN32_WINCE) && PJ_WIN32_WINCE!=0)

    /* On Win32, since we use QueryPerformanceCounter() as the backend
     * timestamp API, we need to protect against this bug:
     *   Performance counter value may unexpectedly leap forward
     *   http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q274323
     */
    {
	/*
	 * Compare elapsed time reported by timestamp with actual elapsed 
	 * time. If the difference is too excessive, then we use system
	 * time instead.
	 */

	/* MIN_DIFF needs to be large enough so that "normal" diff caused
	 * by system activity or context switch doesn't trigger the time
	 * correction.
	 */
	enum { MIN_DIFF = 400 };

	pj_time_val ts_time, elapsed, diff;

	pj_gettimeofday(&elapsed);

	ts_time.sec = ntp->hi - sess->tv_base.sec - JAN_1970;
	ts_time.msec = (long)(ntp->lo * 1000.0 / 0xFFFFFFFF);

	PJ_TIME_VAL_SUB(elapsed, sess->tv_base);

	if (PJ_TIME_VAL_LT(ts_time, elapsed)) {
	    diff = elapsed;
	    PJ_TIME_VAL_SUB(diff, ts_time);
	} else {
	    diff = ts_time;
	    PJ_TIME_VAL_SUB(diff, elapsed);
	}

	if (PJ_TIME_VAL_MSEC(diff) >= MIN_DIFF) {

	    TRACE_((sess->name, "RTCP NTP timestamp corrected by %d ms",
		    PJ_TIME_VAL_MSEC(diff)));


	    ntp->hi = elapsed.sec + sess->tv_base.sec + JAN_1970;
	    ntp->lo = (elapsed.msec * 65536 / 1000) << 16;
	}

    }
#endif

    return status;
}


PJ_DEF(void) pjmedia_rtcp_init(pjmedia_rtcp_session *sess, 
			       char *name,
			       unsigned clock_rate,
			       unsigned samples_per_frame,
			       pj_uint32_t ssrc)
{
    pjmedia_rtcp_pkt *rtcp_pkt = &sess->rtcp_pkt;
    pj_time_val now;
    
    /* Memset everything */
    pj_bzero(sess, sizeof(pjmedia_rtcp_session));

    /* Last RX timestamp in RTP packet */
    sess->rtp_last_ts = (unsigned)-1;

    /* Name */
    sess->name = name ? name : THIS_FILE,

    /* Set clock rate */
    sess->clock_rate = clock_rate;
    sess->pkt_size = samples_per_frame;

    /* Init common RTCP header */
    rtcp_pkt->common.version = 2;
    rtcp_pkt->common.count = 1;
    rtcp_pkt->common.pt = RTCP_SR;
    rtcp_pkt->common.length = pj_htons(12);
    
    /* Init SR */
    rtcp_pkt->sr.ssrc = pj_htonl(ssrc);
    
    /* Get time and timestamp base and frequency */
    pj_gettimeofday(&now);
    sess->tv_base = now;
    sess->stat.start = now;
    pj_get_timestamp(&sess->ts_base);
    pj_get_timestamp_freq(&sess->ts_freq);

    /* RR will be initialized on receipt of the first RTP packet. */
}


PJ_DEF(void) pjmedia_rtcp_fini(pjmedia_rtcp_session *sess)
{
    /* Nothing to do. */
    PJ_UNUSED_ARG(sess);
}

static void rtcp_init_seq(pjmedia_rtcp_session *sess)
{
    sess->received = 0;
    sess->exp_prior = 0;
    sess->rx_prior = 0;
    sess->transit = 0;
    sess->jitter = 0;
}

PJ_DEF(void) pjmedia_rtcp_rx_rtp(pjmedia_rtcp_session *sess, 
				 unsigned seq, 
				 unsigned rtp_ts,
				 unsigned payload)
{   
    pj_timestamp ts;
    pj_uint32_t arrival;
    pj_int32_t transit;
    pjmedia_rtp_status seq_st;
    unsigned last_seq;

    if (sess->stat.rx.pkt == 0) {
	/* Init sequence for the first time. */
	pjmedia_rtp_seq_init(&sess->seq_ctrl, (pj_uint16_t)seq);
    } 

    sess->stat.rx.pkt++;
    sess->stat.rx.bytes += payload;

    /* Process the RTP packet. */
    last_seq = sess->seq_ctrl.max_seq;
    pjmedia_rtp_seq_update(&sess->seq_ctrl, (pj_uint16_t)seq, &seq_st);

    if (seq_st.status.flag.restart) {
	rtcp_init_seq(sess);
    }
    
    if (seq_st.status.flag.dup) {
	sess->stat.rx.dup++;
	TRACE_((sess->name, "Duplicate packet detected"));
    }

    if (seq_st.status.flag.outorder && !seq_st.status.flag.probation) {
	sess->stat.rx.reorder++;
	TRACE_((sess->name, "Out-of-order packet detected"));
    }

    if (seq_st.status.flag.bad) {
	sess->stat.rx.discard++;
	TRACE_((sess->name, "Bad packet discarded"));
	return;
    }

    /* Only mark "good" packets */
    ++sess->received;

    /* Calculate loss periods. */
    if (seq_st.diff > 1) {
	unsigned count = seq_st.diff - 1;
	unsigned period;

	period = count * sess->pkt_size * 1000 / sess->clock_rate;
	period *= 1000;

	/* Update packet lost. 
	 * The packet lost number will also be updated when we're sending
	 * outbound RTCP RR.
	 */
	sess->stat.rx.loss += (seq_st.diff - 1);
	TRACE_((sess->name, "%d packet(s) lost", seq_st.diff - 1));

	/* Update loss period stat */
	if (sess->stat.rx.loss_period.count == 0 ||
	    period < sess->stat.rx.loss_period.min)
	{
	    sess->stat.rx.loss_period.min = period;
	}
	if (period > sess->stat.rx.loss_period.max)
	    sess->stat.rx.loss_period.max = period;
	sess->stat.rx.loss_period.avg = 
	    (sess->stat.rx.loss_period.avg * sess->stat.rx.loss_period.count +
	     period) / (sess->stat.rx.loss_period.count + 1);
	sess->stat.rx.loss_period.last = period;
	++sess->stat.rx.loss_period.count;
    }


    /*
     * Calculate jitter only when sequence is good (see RFC 3550 section A.8),
     * AND only when the timestamp is different than the last packet
     * (see RTP FAQ).
     */
    if (seq_st.diff == 1 && rtp_ts != sess->rtp_last_ts) {
	/* Get arrival time and convert timestamp to samples */
	pj_get_timestamp(&ts);
	ts.u64 = ts.u64 * sess->clock_rate / sess->ts_freq.u64;
	arrival = ts.u32.lo;

	transit = arrival - rtp_ts;
    
	/* Ignore the first N packets as they normally have bad jitter
	 * due to other threads working to establish the call
	 */
	if (sess->transit == 0 || 
	    sess->received < PJMEDIA_RTCP_IGNORE_FIRST_PACKETS) 
	{
	    sess->transit = transit;
	    sess->stat.rx.jitter.min = 2000;
	} else {
	    pj_int32_t d;
	    pj_uint32_t jitter;
	    
	    d = transit - sess->transit;
	    sess->transit = transit;
	    if (d < 0) 
		d = -d;
	    
	    sess->jitter += d - ((sess->jitter + 8) >> 4);

	    /* Get jitter in usec */
	    if (d < 4294)
		jitter = d * 1000000 / sess->clock_rate;
	    else {
		jitter = d * 1000 / sess->clock_rate;
		jitter *= 1000;
	    }

	    /* Add to average */
	    sess->avg_jitter = 
		(jitter + sess->avg_jitter * sess->stat.rx.jitter.count) /
		(sess->stat.rx.jitter.count + 1);
	    sess->stat.rx.jitter.avg = (unsigned)sess->avg_jitter;
	    ++sess->stat.rx.jitter.count;

	    /* Update jitter stat */
	    if (jitter < sess->stat.rx.jitter.min)
		sess->stat.rx.jitter.min = jitter;
	    if (jitter > sess->stat.rx.jitter.max)
		sess->stat.rx.jitter.max = jitter;

	    sess->stat.rx.jitter.last = jitter;
	}
    }

    /* Update timestamp of last RX RTP packet */
    sess->rtp_last_ts = rtp_ts;
}

PJ_DEF(void) pjmedia_rtcp_tx_rtp(pjmedia_rtcp_session *sess, 
				 unsigned bytes_payload_size)
{