osmux: Set Marker bit on osmux frame loss detected

Until this patch, we didn't notify in any way to the RTP reader when an
Osmux frame was lost. Instead, we updated the seq&timestamp as if there
was no lost, and as a result the RTP reader would only see a steady
increase of delay every time an osmux frame was lost.

As the batch_factor for the lost packet is unknown, we cannot assume any
number of amr payloads lost, and thus we cannot simply increment seq and
timestamp for a specific amount. Instead, the only viable solution seems
to set the M marker bit in the first rtp packet generated after a
non-consecutive osmux frame is received.

The implementation may act differently with the first generated RTP
packet based on the first osmux seq number used for the stream. In case
0 it's used as first osmux seq number, M will be set depending on
request from original RTP packet having the M bit set. If it's not 0,
the first RTP packer will unconditionally have the M bit. That's not an
issue because it's anyway expect for receiver to sync on the first
packet.

Related: OS#3185

Change-Id: I2efed6d726a1b8e77e686c7a5fe1940d3f4901a7

2 files changed, 17 insertions, 10 deletions

diff --git a/tests/osmux/osmux_test.c b/tests/osmux/osmux_test.c
index 01ce2d1..631ade8 100644
--- a/tests/osmux/osmux_test.c
+++ b/tests/osmux/osmux_test.c
@@ -152,7 +152,8 @@ static void osmux_test_marker(int ccid) {
 			memcpy(msg->data, rtp_pkt, sizeof(rtp_pkt));
 			cpy_rtph = (struct rtp_hdr *) msgb_put(msg, sizeof(rtp_pkt));
 
-			if ((i+j) % 7 == 0) {
+			/* first condition guarantees that 1st packet per stream contains M bit set. */
+			if (i == 0 || (i+j) % 7 == 0) {
 				cpy_rtph->marker = 1;
 				mark_pkts++;
 			}
@@ -175,7 +176,7 @@ static void osmux_test_marker(int ccid) {
 	}
 
 	if (mark_pkts) {
-		fprintf(stdout, "RTP M bit (marker) mismatch! %d\n", mark_pkts);
+		fprintf(stdout, "osmux_test_marker: RTP M bit (marker) mismatch! %d\n", mark_pkts);
 		exit(EXIT_FAILURE);
 	}
 }
@@ -183,6 +184,7 @@ static void osmux_test_marker(int ccid) {
 static void osmux_test_loop(int ccid)
 {
 	struct rtp_hdr *rtph = (struct rtp_hdr *)rtp_pkt;
+	struct rtp_hdr *cpy_rtph;
 	struct msgb *msg;
 	int i, j, k = 0;
 	char buf[1024];
@@ -194,11 +196,16 @@ static void osmux_test_loop(int ccid)
 			exit(EXIT_FAILURE);
 
 		memcpy(msg->data, rtp_pkt, sizeof(rtp_pkt));
-		msgb_put(msg, sizeof(rtp_pkt));
+		cpy_rtph = (struct rtp_hdr *) msgb_put(msg, sizeof(rtp_pkt));
 
 		seq = ntohs(rtph->sequence);
 		seq++;
 		rtph->sequence = htons(seq);
+		if (i < 3) {
+			/* Mark 1 rtp packet of each stream */
+			cpy_rtph->marker = 1;
+			mark_pkts++;
+		}
 
 		osmo_rtp_snprintf(buf, sizeof(buf), msg);
 		fprintf(stderr, "adding to ccid=%u %s\n", (i % 2) + ccid, buf);
@@ -239,7 +246,7 @@ static void osmux_test_loop(int ccid)
 	}
 
 	if (mark_pkts) {
-		fprintf(stdout, "RTP M bit (marker) mismatch! %d\n", mark_pkts);
+		fprintf(stdout, "osmux_test_loop: RTP M bit (marker) mismatch! %d\n", mark_pkts);
 		exit(EXIT_FAILURE);
 	}
 }
diff --git a/tests/osmux/osmux_test2.ok b/tests/osmux/osmux_test2.ok
index 1e6f95a..53ab67d 100644
--- a/tests/osmux/osmux_test2.ok
+++ b/tests/osmux/osmux_test2.ok
@@ -1,6 +1,6 @@
 ===test_output_consecutive===
 sys={0.000000}, mono={0.000000}: clock_override_set
-sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 enqueued=5
+sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 M enqueued=5
 sys={0.000000}, mono={0.000000}: first dequed before first select
 sys={0.020000}, mono={0.020000}: clock_override_add
 sys={0.020000}, mono={0.020000}: second select, second dequed
@@ -32,7 +32,7 @@ sys={0.200000}, mono={0.200000}: dequeue: seq=61 ts=2260 enqueued=0
 sys={0.200000}, mono={0.200000}: calling flush on empty list, should do nothing
 ===test_output_interleaved===
 sys={0.000000}, mono={0.000000}: clock_override_set
-sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 enqueued=5
+sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 M enqueued=5
 sys={0.040000}, mono={0.040000}: clock_override_add
 sys={0.040000}, mono={0.040000}: select, 3 dequed, 3 still queued
 sys={0.040000}, mono={0.040000}: dequeue: seq=51 ts=660 enqueued=4
@@ -51,7 +51,7 @@ sys={0.140000}, mono={0.140000}: dequeue: seq=60 ts=2100 enqueued=1
 sys={0.140000}, mono={0.140000}: dequeue: seq=61 ts=2260 enqueued=0
 ===test_output_2together===
 sys={0.000000}, mono={0.000000}: clock_override_set
-sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 enqueued=5
+sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 M enqueued=5
 sys={0.000000}, mono={0.000000}: calling select in between 2 osmux recv
 sys={0.000000}, mono={0.000000}: calling select after receiving 2nd osmux. Dequeue 1st osmux frame and 1st rtp from 2nd osmux frame.
 sys={0.000000}, mono={0.000000}: dequeue: seq=51 ts=660 enqueued=10
@@ -70,7 +70,7 @@ sys={0.100000}, mono={0.100000}: dequeue: seq=61 ts=2260 enqueued=0
 ===test_output_frame_lost===
 sys={0.000000}, mono={0.000000}: clock_override_set
 sys={0.000000}, mono={0.000000}: first osmux frame
-sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 enqueued=5
+sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 M enqueued=5
 sys={0.100000}, mono={0.100000}: clock_override_add
 sys={0.100000}, mono={0.100000}: dequeue: seq=51 ts=660 enqueued=4
 sys={0.100000}, mono={0.100000}: dequeue: seq=52 ts=820 enqueued=3
@@ -80,7 +80,7 @@ sys={0.100000}, mono={0.100000}: dequeue: seq=55 ts=1300 enqueued=0
 sys={0.100000}, mono={0.100000}: one osmux frame is now lost (seq++)
 sys={0.220000}, mono={0.220000}: clock_override_add
 sys={0.220000}, mono={0.220000}: 3rd osmux frame arrives
-sys={0.220000}, mono={0.220000}: dequeue: seq=56 ts=1460 enqueued=5
+sys={0.220000}, mono={0.220000}: dequeue: seq=56 ts=1460 M enqueued=5
 sys={0.320000}, mono={0.320000}: clock_override_add
 sys={0.320000}, mono={0.320000}: dequeue: seq=57 ts=1620 enqueued=4
 sys={0.320000}, mono={0.320000}: dequeue: seq=58 ts=1780 enqueued=3
@@ -90,7 +90,7 @@ sys={0.320000}, mono={0.320000}: dequeue: seq=61 ts=2260 enqueued=0
 ===test_output_flush===
 sys={0.000000}, mono={0.000000}: clock_override_set
 sys={0.000000}, mono={0.000000}: first osmux frame
-sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 enqueued=5
+sys={0.000000}, mono={0.000000}: dequeue: seq=50 ts=500 M enqueued=5
 sys={0.040000}, mono={0.040000}: clock_override_add
 sys={0.040000}, mono={0.040000}: dequeue: seq=51 ts=660 enqueued=4
 sys={0.040000}, mono={0.040000}: dequeue: seq=52 ts=820 enqueued=3