[PATCH 1/3] mgcp/rtp: Refactor timestamp offset calculation into own function

Currently the timestamp offset calculation is done in two different places. This patch moves and unifies both code parts into a separate function. Sponsored-by: On-Waves ehf --- openbsc/src/libmgcp/mgcp_network.c | 98 ++++++++++++++++++++++++------------ 1 file changed, 66 insertions(+), 32 deletions(-) diff --git a/openbsc/src/libmgcp/mgcp_network.c b/openbsc/src/libmgcp/mgcp_network.c index bf205d1..8bd8afb 100644 --- a/openbsc/src/libmgcp/mgcp_network.c +++ b/openbsc/src/libmgcp/mgcp_network.c @@ -200,6 +200,58 @@ static int check_rtp_timestamp(struct mgcp_endpoint *endp, return 1; } +/* Set the timestamp offset according to the packet duration. */ +static int adjust_rtp_timestamp_offset(struct mgcp_endpoint *endp, + struct mgcp_rtp_state *state, + struct mgcp_rtp_end *rtp_end, + struct sockaddr_in *addr, + int16_t delta_seq, uint32_t timestamp) +{ + int32_t tsdelta = state->packet_duration; + int timestamp_offset; + + if (tsdelta == 0) { + tsdelta = state->out_stream.last_tsdelta; + if (tsdelta != 0) { + LOGP(DMGCP, LOGL_NOTICE, + "A fixed packet duration is not available on 0x%x, " + "using last output timestamp delta instead: %d " + "from %s:%d in %d\n", + ENDPOINT_NUMBER(endp), tsdelta, + inet_ntoa(addr->sin_addr), ntohs(addr->sin_port), + endp->conn_mode); + } else { + tsdelta = rtp_end->rate * 20 / 1000; + LOGP(DMGCP, LOGL_NOTICE, + "Fixed packet duration and last timestamp delta " + "are not available on 0x%x, " + "using fixed 20ms instead: %d " + "from %s:%d in %d\n", + ENDPOINT_NUMBER(endp), tsdelta, + inet_ntoa(addr->sin_addr), ntohs(addr->sin_port), + endp->conn_mode); + } + } + + timestamp_offset = + state->out_stream.last_timestamp - timestamp + + delta_seq * tsdelta; + + if (state->timestamp_offset != timestamp_offset) { + state->timestamp_offset = timestamp_offset; + + LOGP(DMGCP, LOGL_NOTICE, + "Timestamp offset change on 0x%x SSRC: %u " + "SeqNo delta: %d, TS offset: %d, " + "from %s:%d in %d\n", + ENDPOINT_NUMBER(endp), state->in_stream.ssrc, + delta_seq, state->timestamp_offset, + inet_ntoa(addr->sin_addr), ntohs(addr->sin_port), + endp->conn_mode); + } + + return timestamp_offset; +} /** * The RFC 3550 Appendix A assumes there are multiple sources but @@ -259,22 +311,14 @@ void mgcp_patch_and_count(struct mgcp_endpoint *endp, struct mgcp_rtp_state *sta state->in_stream.ssrc = ssrc; if (rtp_end->force_constant_ssrc) { - int32_t tsdelta = state->out_stream.last_tsdelta; - if (tsdelta == 0) { - tsdelta = state->packet_duration; - LOGP(DMGCP, LOGL_NOTICE, - "Timestamp delta is not available on 0x%x, " - "using packet duration instead: %d " - "from %s:%d in %d\n", - ENDPOINT_NUMBER(endp), tsdelta, - inet_ntoa(addr->sin_addr), ntohs(addr->sin_port), - endp->conn_mode); - } + const int16_t delta_seq = 1; + state->seq_offset = - (state->out_stream.last_seq + 1) - seq; - state->timestamp_offset = - (state->out_stream.last_timestamp + tsdelta) - - timestamp; + (state->out_stream.last_seq + delta_seq) - seq; + + adjust_rtp_timestamp_offset(endp, state, rtp_end, addr, + delta_seq, timestamp); + state->patch_ssrc = 1; ssrc = state->orig_ssrc; if (rtp_end->force_constant_ssrc != -1) @@ -282,10 +326,10 @@ void mgcp_patch_and_count(struct mgcp_endpoint *endp, struct mgcp_rtp_state *sta LOGP(DMGCP, LOGL_NOTICE, "SSRC patching enabled on 0x%x SSRC: %u " - "offset: %d tsdelta: %d " + "SeqNo offset: %d, TS offset: %d " "from %s:%d in %d\n", ENDPOINT_NUMBER(endp), state->in_stream.ssrc, - state->seq_offset, tsdelta, + state->seq_offset, state->timestamp_offset, inet_ntoa(addr->sin_addr), ntohs(addr->sin_port), endp->conn_mode); } @@ -307,22 +351,12 @@ void mgcp_patch_and_count(struct mgcp_endpoint *endp, struct mgcp_rtp_state *sta if (rtp_end->force_constant_timing && state->out_stream.ssrc == ssrc && state->packet_duration) { - int delta_seq = seq + state->seq_offset - state->out_stream.last_seq; - int timestamp_offset = - state->out_stream.last_timestamp - timestamp + - delta_seq * state->packet_duration; - if (state->timestamp_offset != timestamp_offset) { - state->timestamp_offset = timestamp_offset; + /* Update the timestamp offset */ + const int delta_seq = + seq + state->seq_offset - state->out_stream.last_seq; - LOGP(DMGCP, LOGL_NOTICE, - "Timestamp patching enabled on 0x%x SSRC: %u " - "SeqNo delta: %d, TS offset: %d, " - "from %s:%d in %d\n", - ENDPOINT_NUMBER(endp), state->in_stream.ssrc, - delta_seq, state->timestamp_offset, - inet_ntoa(addr->sin_addr), ntohs(addr->sin_port), - endp->conn_mode); - } + adjust_rtp_timestamp_offset(endp, state, rtp_end, addr, + delta_seq, timestamp); } /* Store the updated SSRC back to the packet */ -- 1.7.9.5