--- rtp.c	2007-04-26 17:08:30.000000000 +0100
+++ rtp.c.rttfixed	2007-04-26 17:10:47.000000000 +0100
@@ -831,15 +831,16 @@
 	struct timeval now;
 	unsigned int length;
 	int rc;
-	double rtt = 0;
-	double a;
-	double dlsr;
-	double lsr;
+	double rttsec;
+	uint64_t rtt;
+	unsigned int dlsr;
+	unsigned int lsr;
 	unsigned int msw;
 	unsigned int lsw;
 	unsigned int comp;
 	struct ast_frame *f = &ast_null_frame;
 	
+	
 	if (!rtp || !rtp->rtcp)
 		return &ast_null_frame;
 
@@ -914,26 +915,45 @@
 				break;
 			/* Intentional fall through */
 		case RTCP_PT_RR:
-			/* This is the place to calculate RTT */
 			/* Don't handle multiple reception reports (rc > 1) yet */
+				/* Calculate RTT per RFC */
 			gettimeofday(&now, NULL);
 			timeval2ntp(now, &msw, &lsw);
-			/* Use the one we sent them in our SR instead, rtcp->txlsr could have been rewritten if the dlsr is large */
-			if (ntohl(rtcpheader[i + 4])) { /* We must have the LSR */
+				if (ntohl(rtcpheader[i + 4]) && ntohl(rtcpheader[i + 5])) { /* We must have the LSR && DLSR */
 				comp = ((msw & 0xffff) << 16) | ((lsw & 0xffff0000) >> 16);
-				a = (double)((comp & 0xffff0000) >> 16) + (double)((double)(comp & 0xffff)/1000000.);
-				lsr = (double)((ntohl(rtcpheader[i + 4]) & 0xffff0000) >> 16) + (double)((double)(ntohl(rtcpheader[i + 4]) & 0xffff) / 1000000.);
-				dlsr = (double)(ntohl(rtcpheader[i + 5])/65536.);
-				rtt = a - dlsr - lsr;
-				if (rtt >= 0) {
-					rtp->rtcp->accumulated_transit += rtt;
-					rtp->rtcp->rtt = rtt;
-					if (rtp->rtcp->maxrtt < rtt)
-						rtp->rtcp->maxrtt = rtt;
-					if (rtp->rtcp->minrtt > rtt)
-						rtp->rtcp->minrtt = rtt;
+					lsr = ntohl(rtcpheader[i+4]);
+					dlsr = ntohl(rtcpheader[i+5]);
+					rtt = comp - lsr - dlsr;
+
+					/* Convert end to end delay to usec (keeping the calculation in 64bit space)
+					   sess->ee_delay = (eedelay * 1000) / 65536; */
+					if (rtt < 4294) {
+					    rtt = (rtt * 1000000) >> 16;
+					} else {
+					    rtt = (rtt * 1000) >> 16;
+					    rtt *= 1000;
 				}
+					rtt = rtt/1000.;
+					rttsec = rtt/1000.;
+
+					if (comp-dlsr >= lsr) {
+						rtp->rtcp->accumulated_transit += rttsec;
+						rtp->rtcp->rtt = rttsec;
+						if (rtp->rtcp->maxrtt<rttsec)
+							rtp->rtcp->maxrtt = rttsec;
+						if (rtp->rtcp->minrtt>rttsec)
+							rtp->rtcp->minrtt = rttsec;
+					} else {
+						ast_verbose("Internal RTCP NTP clock skew detected: "
+								   "lsr=%p, now=%p, dlsr=%p (%d:%03dms), "
+								   "diff=%d",
+								   lsr, comp, dlsr, dlsr/65536,
+								   (dlsr%65536)*1000/65536,
+								   dlsr-(comp-lsr));
 			}
+				}
+
+
 			rtp->rtcp->reported_jitter = ntohl(rtcpheader[i + 3]);
 			rtp->rtcp->reported_lost = ntohl(rtcpheader[i + 1]) & 0xffffff;
 			if (rtcp_debug_test_addr(&sin)) {