[core] Add RTP_BUG_DONT_REPORT_FLUSHED_AS_LOST to exclude flushed packets from RTCP loss

src/include/switch_types.h

@@ -739,6 +739,7 @@ typedef struct {
 	uint32_t last_rpt_ext_seq;    /* Packet loss calculation, extended sequence number at the begining of this RTCP report interval */
 	uint16_t last_rpt_cycle;      /* Packet loss calculation, sequence number cycle at the begining of the current RTCP report interval */
 	uint16_t period_pkt_count;    /* Packet loss calculation, packet count received during this RTCP report interval */
+	switch_size_t last_rpt_flush_count; /* inbound.flush_packet_count at the start of this RTCP report interval (RTP_BUG_DONT_REPORT_FLUSHED_AS_LOST) */
 	uint16_t pkt_count;           /* Packet loss calculation, packet count received during this session */
 	uint16_t sent_pkt_count;
 	uint32_t rtcp_rtp_count;      /* RTCP report generated count */
@@ -975,13 +976,21 @@ typedef enum {
 	*/
 
 
-	RTP_BUG_ALWAYS_AUTO_ADJUST = (1 << 12)
+	RTP_BUG_ALWAYS_AUTO_ADJUST = (1 << 12),
 
 	/*
 	  Leave the auto-adjust behavior enableed permenantly rather than only at appropriate times.  (IMPLICITLY sets RTP_BUG_ACCEPT_ANY_PACKETS)
 
 	 */
 
+	RTP_BUG_DONT_REPORT_FLUSHED_AS_LOST = (1 << 13)
+
+	/*
+	  Do not count packets FreeSWITCH itself flushed (do_flush) as lost in the RTCP
+	  receiver report. They arrived over the network; discarding them locally is not
+	  transport loss. Genuine network loss (packets that never arrived) is still reported.
+	 */
+
 } switch_rtp_bug_flag_t;
 
 #ifdef _MSC_VER

src/switch_core_media.c

@@ -1018,6 +1018,14 @@ SWITCH_DECLARE(void) switch_core_media_parse_rtp_bugs(switch_rtp_bug_flag_t *fla
 		*flag_pole &= ~RTP_BUG_FLUSH_JB_ON_DTMF;
 	}
 
+	if (switch_stristr("DONT_REPORT_FLUSHED_AS_LOST", str)) {
+		*flag_pole |= RTP_BUG_DONT_REPORT_FLUSHED_AS_LOST;
+	}
+
+	if (switch_stristr("~DONT_REPORT_FLUSHED_AS_LOST", str)) {
+		*flag_pole &= ~RTP_BUG_DONT_REPORT_FLUSHED_AS_LOST;
+	}
+
 	if (switch_stristr("ALWAYS_AUTO_ADJUST", str)) {
 		*flag_pole |= (RTP_BUG_ALWAYS_AUTO_ADJUST | RTP_BUG_ACCEPT_ANY_PACKETS);
 	}

src/switch_rtp.c

@@ -1854,6 +1854,14 @@ static void rtcp_generate_report_block(switch_rtp_t *rtp_session, struct switch_
 	}
 
 	pkt_lost = expected_pkt - stats->period_pkt_count;
+
+	if (rtp_session->rtp_bugs & RTP_BUG_DONT_REPORT_FLUSHED_AS_LOST) {
+		switch_size_t fc = rtp_session->stats.inbound.flush_packet_count;
+		if (fc > stats->last_rpt_flush_count) {
+			pkt_lost -= (int32_t)(fc - stats->last_rpt_flush_count); /* flushed by FS = arrived, not transport loss */
+		}
+	}
+
 	if (pkt_lost < 0) pkt_lost = 0;
 
 	stats->cum_lost=stats->cum_lost+pkt_lost;
@@ -1920,6 +1928,7 @@ static void rtcp_stats_init(switch_rtp_t *rtp_session)
 	stats->bad_seq = (1<<16) + 1; /* Make sure we wont missmatch 2 consecutive packets, so seq == bad_seq is false */
 	stats->cum_lost = 0;
 	stats->period_pkt_count = 0;
+	stats->last_rpt_flush_count = rtp_session->stats.inbound.flush_packet_count;
 	stats->sent_pkt_count = 0;
 	stats->pkt_count = 0;
 	stats->rtcp_rtp_count = 0;
@@ -2468,6 +2477,7 @@ static int check_rtcp_and_ice(switch_rtp_t *rtp_session)
 			stats->last_rpt_ext_seq = stats->high_ext_seq_recv;
 			stats->last_rpt_ts = rtp_session->write_timer.samplecount;
 			stats->period_pkt_count = 0;
+			stats->last_rpt_flush_count = rtp_session->stats.inbound.flush_packet_count;
 		}