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Diffstat (limited to 'openbsc/src/mgcp/mgcp_network.c')
-rw-r--r--openbsc/src/mgcp/mgcp_network.c28
1 files changed, 25 insertions, 3 deletions
diff --git a/openbsc/src/mgcp/mgcp_network.c b/openbsc/src/mgcp/mgcp_network.c
index d2dbeebe4..b5e2cddf8 100644
--- a/openbsc/src/mgcp/mgcp_network.c
+++ b/openbsc/src/mgcp/mgcp_network.c
@@ -97,6 +97,7 @@ int mgcp_send_dummy(struct mgcp_endpoint *endp)
static void patch_and_count(struct mgcp_rtp_state *state, int payload, char *data, int len)
{
uint16_t seq;
+ uint32_t timestamp;
struct rtp_hdr *rtp_hdr;
if (len < sizeof(*rtp_hdr))
@@ -104,15 +105,36 @@ static void patch_and_count(struct mgcp_rtp_state *state, int payload, char *dat
rtp_hdr = (struct rtp_hdr *) data;
seq = ntohs(rtp_hdr->sequence);
+ timestamp = ntohl(rtp_hdr->timestamp);
if (!state->initialized) {
- state->seq_no = seq;
+ state->seq_no = seq - 1;
+ state->ssrc = state->orig_ssrc = rtp_hdr->ssrc;
state->initialized = 1;
- } else if (state->seq_no + 1u != seq)
- state->lost_no = abs(seq - (state->seq_no + 1));
+ state->last_timestamp = timestamp;
+ } else if (state->ssrc != rtp_hdr->ssrc) {
+ state->ssrc = rtp_hdr->ssrc;
+ state->seq_offset = (state->seq_no + 1) - seq;
+ state->timestamp_offset = state->last_timestamp - timestamp;
+ LOGP(DMGCP, LOGL_NOTICE, "The SSRC changed... SSRC: %u offset: %d\n",
+ state->ssrc, state->seq_offset);
+ }
+
+ /* apply the offset and store it back to the packet */
+ seq += state->seq_offset;
+ rtp_hdr->sequence = htons(seq);
+ rtp_hdr->ssrc = state->orig_ssrc;
+ timestamp += state->timestamp_offset;
+ rtp_hdr->timestamp = htonl(timestamp);
+
+ /* seq changed, now compare if we have lost something */
+ if (state->seq_no + 1u != seq)
+ state->lost_no = abs(seq - (state->seq_no + 1));
state->seq_no = seq;
+ state->last_timestamp = timestamp;
+
if (payload < 0)
return;