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libosmo-netif
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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
This commit is contained in:
Pau Espin 2018-04-18 19:10:20 +02:00
parent 9452adcc33
commit e259c8ab18
4 changed files with 34 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/osmocom/netif/osmux.h
View File

@ -80,6 +80,7 @@ struct osmux_out_handle {
uint16_t rtp_seq;
uint32_t rtp_timestamp;
uint32_t rtp_ssrc;
uint8_t osmux_seq_ack; /* Latest received seq num */
struct osmo_timer_list timer;
struct llist_head list;
void (*tx_cb)(struct msgb *msg, void *data); /* Used defined rtp tx callback */

18
src/osmux.c
View File

@ -151,8 +151,14 @@ osmux_rebuild_rtp(struct osmux_out_handle *h, struct osmux_hdr *osmuxh,
rtph->timestamp = htonl(h->rtp_timestamp);
rtph->sequence = htons(h->rtp_seq);
rtph->ssrc = htonl(h->rtp_ssrc);
/* rtp packet with the marker bit is always warranted to be the first one */
rtph->marker = first_pkt && osmuxh->rtp_m;
/* rtp packet with the marker bit is always guaranteed to be the first
* one. We want to notify with marker in 2 scenarios:
* 1- Sender told us through osmux frame rtp_m.
* 2- Sntermediate osmux frame lost (seq gap), otherwise rtp receiver only sees
* steady increase of delay
*/
rtph->marker = first_pkt &&
(osmuxh->rtp_m || (osmuxh->seq != h->osmux_seq_ack + 1));
msgb_put(out_msg, sizeof(struct rtp_hdr));
@ -218,6 +224,10 @@ int osmux_xfrm_output(struct osmux_hdr *osmuxh, struct osmux_out_handle *h,
#endif
llist_add_tail(&msg->list, list);
}
/* Update last seen seq number: */
h->osmux_seq_ack = osmuxh->seq;
return i;
}
@ -291,6 +301,10 @@ int osmux_xfrm_output_sched(struct osmux_out_handle *h, struct osmux_hdr *osmuxh
llist_add_tail(&msg->list, &h->list);
}
/* Update last seen seq number: */
h->osmux_seq_ack = osmuxh->seq;
/* In case list is still empty after parsing messages, no need to rearm */
if(was_empty && !llist_empty(&h->list))
osmux_xfrm_output_trigger(h);

15
tests/osmux/osmux_test.c
View File

@ -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);
}
}

12
tests/osmux/osmux_test2.ok
View File

@ -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