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Jacob Erlbeck jerlbeck at sysmocom.deThis patch parses the 'ptime' and 'maxptime' SDP attributes, and the
SDP rate information and sets up packet_duration_ms accordingly. If
the packet duration is unknown or allows for different values (e.g.
because 'ptime' uses a range or 'maxptime' allows for more than one
frame) the duration is set to 0.
Sponsored-by: On-Waves ehf
---
openbsc/src/libmgcp/mgcp_network.c | 9 ++++++
openbsc/src/libmgcp/mgcp_protocol.c | 53 +++++++++++++++++++++++++++++++----
openbsc/tests/mgcp/mgcp_test.c | 4 +++
openbsc/tests/mgcp/mgcp_test.ok | 10 +++----
4 files changed, 65 insertions(+), 11 deletions(-)
diff --git a/openbsc/src/libmgcp/mgcp_network.c b/openbsc/src/libmgcp/mgcp_network.c
index 8bd8afb..40227af 100644
--- a/openbsc/src/libmgcp/mgcp_network.c
+++ b/openbsc/src/libmgcp/mgcp_network.c
@@ -300,6 +300,15 @@ void mgcp_patch_and_count(struct mgcp_endpoint *endp, struct mgcp_rtp_state *sta
state->seq_offset, state->packet_duration,
inet_ntoa(addr->sin_addr), ntohs(addr->sin_port),
endp->conn_mode);
+ if (state->packet_duration == 0 && rtp_end->force_constant_timing)
+ LOGP(DMGCP, LOGL_ERROR,
+ "Cannot patch timestamps on 0x%x: "
+ "RTP packet duration is unknown, SSRC: %u, "
+ "from %s:%d in %d\n",
+ ENDPOINT_NUMBER(endp), state->in_stream.ssrc,
+ inet_ntoa(addr->sin_addr), ntohs(addr->sin_port),
+ endp->conn_mode);
+
} else if (state->in_stream.ssrc != ssrc) {
LOGP(DMGCP, LOGL_NOTICE,
"The SSRC changed on 0x%x: %u -> %u "
diff --git a/openbsc/src/libmgcp/mgcp_protocol.c b/openbsc/src/libmgcp/mgcp_protocol.c
index 5403861..b9e1382 100644
--- a/openbsc/src/libmgcp/mgcp_protocol.c
+++ b/openbsc/src/libmgcp/mgcp_protocol.c
@@ -562,25 +562,64 @@ static int parse_sdp_data(struct mgcp_rtp_end *rtp, struct mgcp_parse_data *p)
{
char *line;
int found_media = 0;
+ int audio_payload = -1;
for_each_line(line, p->save) {
switch (line[0]) {
- case 'a':
case 'o':
case 's':
case 't':
case 'v':
/* skip these SDP attributes */
break;
+ case 'a': {
+ int payload;
+ int rate;
+ int channels = 1;
+ int ptime, ptime2 = 0;
+ char audio_name[64];
+ char audio_codec[64];
+
+ if (audio_payload == -1)
+ break;
+
+ if (sscanf(line, "a=rtpmap:%d %64s",
+ &payload, audio_name) == 2) {
+ if (payload != audio_payload)
+ break;
+
+ if (sscanf(audio_name, "%[^/]/%d/%d",
+ audio_codec, &rate, &channels) < 2)
+ break;
+
+ rtp->rate = rate;
+ if (channels != 1)
+ LOGP(DMGCP, LOGL_NOTICE,
+ "Channels != 1 in SDP: '%s' on 0x%x\n",
+ line, ENDPOINT_NUMBER(p->endp));
+ } else if (sscanf(line, "a=ptime:%d-%d",
+ &ptime, &ptime2) >= 1) {
+ if (ptime2 > 0 && ptime2 != ptime)
+ rtp->packet_duration_ms = 0;
+ else
+ rtp->packet_duration_ms = ptime;
+ } else if (sscanf(line, "a=maxptime:%d", &ptime2) == 1) {
+ if (ptime2 * rtp->frame_duration_den >
+ rtp->frame_duration_num * 1500)
+ /* more than 1 frame */
+ rtp->packet_duration_ms = 0;
+ }
+ break;
+ }
case 'm': {
int port;
- int payload;
+ audio_payload = -1;
if (sscanf(line, "m=audio %d RTP/AVP %d",
- &port, &payload) == 2) {
+ &port, &audio_payload) == 2) {
rtp->rtp_port = htons(port);
rtp->rtcp_port = htons(port + 1);
- rtp->payload_type = payload;
+ rtp->payload_type = audio_payload;
found_media = 1;
}
break;
@@ -608,8 +647,10 @@ static int parse_sdp_data(struct mgcp_rtp_end *rtp, struct mgcp_parse_data *p)
if (found_media)
LOGP(DMGCP, LOGL_NOTICE,
- "Got media info via SDP: port %d, payload %d, addr %s\n",
- ntohs(rtp->rtp_port), rtp->payload_type, inet_ntoa(rtp->addr));
+ "Got media info via SDP: port %d, payload %d, "
+ "duration %d, addr %s\n",
+ ntohs(rtp->rtp_port), rtp->payload_type,
+ rtp->packet_duration_ms, inet_ntoa(rtp->addr));
return found_media;
}
diff --git a/openbsc/tests/mgcp/mgcp_test.c b/openbsc/tests/mgcp/mgcp_test.c
index 3591124..8768426 100644
--- a/openbsc/tests/mgcp/mgcp_test.c
+++ b/openbsc/tests/mgcp/mgcp_test.c
@@ -636,6 +636,10 @@ static void test_packet_error_detection(int patch_ssrc, int patch_ts)
* trunk.endpoints are set up properly. */
mgcp_free_endp(&endp);
+ /* There is no MGCP/SDP around, so set this by hand to make timestamp
+ * patching possible */
+ rtp->packet_duration_ms = 20;
+
rtp->payload_type = 98;
for (i = 0; i < ARRAY_SIZE(test_rtp_packets1); ++i) {
diff --git a/openbsc/tests/mgcp/mgcp_test.ok b/openbsc/tests/mgcp/mgcp_test.ok
index 24f9b33..f9dd7cb 100644
--- a/openbsc/tests/mgcp/mgcp_test.ok
+++ b/openbsc/tests/mgcp/mgcp_test.ok
@@ -16,22 +16,22 @@ Testing AUEP2
Testing MDCX1
Testing MDCX2
Testing CRCX
-Packet duration not set
+Detected packet duration: 40
Requested packetetization period: 20-20
Testing MDCX3
Packet duration not set
Requested packetization period not set
Testing MDCX4
-Packet duration not set
+Detected packet duration: 40
Requested packetetization period: 20-20
Testing MDCX4_PT1
-Packet duration not set
+Detected packet duration: 40
Requested packetetization period: 20-40
Testing MDCX4_PT2
-Packet duration not set
+Detected packet duration: 40
Requested packetetization period: 20-20
Testing MDCX4_PT3
-Packet duration not set
+Detected packet duration: 40
Requested packetization period not set
Testing DLCX
Detected packet duration: 20
--
1.7.9.5