neels has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-msc/+/35307?usp=email )
Change subject: SDP/MGCP: pass octet-align=1 for AMR / pass all fmtp ......................................................................
SDP/MGCP: pass octet-align=1 for AMR / pass all fmtp
Since recent libosmo-mgcp-client update (see Depends), we can now pass fmtp for each individual codec entry to be sent in the SDP. Use that new feature to pass any fmtp from rtp_stream.c to the MGW via MGCP.
In effect, this adds the 'octet-align=1', defined in codec_mapping.c as the default for AMR, which was missing from the SDP/MGCP that osmo-msc sends out.
A 2G to 2G call worked out OK without it, because omitting the 'octet-align' setting from MGCP disables all octet-align payload checks in osmo-mgw. Both 2G call legs use octet-align=1, and things work out.
Running a call from 3G to 2G before this patch would result in osmo-mgw dropping the RTP with logging like:
DRTP NOTICE (rtpbridge/1@bsc0 I:B38CF524) rx_rtp(44 bytes): Expected RTP AMR octet-aligned=1 but got octet-aligned=0. check the config of your call-agent! (mgcp_network.c:1527)
...because osmo-bsc's MGW was instructed to expect octet-align=1, while osmo-msc's MGW emits octet-align=0. This happens because converting the 3G IuUP to 2G AMR heeds the RFC 6871 specified default of octet-align=0.
Depends: osmo-mgw If58590bda8627519ff07e0b6f43aa47a274f052b Change-Id: Ief9225c9bcf7525a9a0a07c282ffb8cc0d092186 --- M src/libmsc/rtp_stream.c 1 file changed, 32 insertions(+), 0 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-msc refs/changes/07/35307/1
diff --git a/src/libmsc/rtp_stream.c b/src/libmsc/rtp_stream.c index 1f885c5..38bf2ba 100644 --- a/src/libmsc/rtp_stream.c +++ b/src/libmsc/rtp_stream.c @@ -334,6 +334,7 @@ .codec = m->mgcp, .pt = codec->payload_type, }; + OSMO_STRLCPY_ARRAY(verb_info.ptmap[i].fmtp, codec->fmtp); i++; verb_info.codecs_len = i; verb_info.ptmap_len = i;