RTCP SDES contains bogus information
When looking at the RTCP generated by osmo-bts, we see bogus content, such as "unknown@unknown" as CNAME and only the ORTP version as "TOOL" name.
Would be better to use libortp's rtp_session_set_source_description() API to put in some reasonable values. Of course RFC3550 didn't assume/expect GSM / cellular usage, so the recommendations for the content of CNAME, NAME, EMAIL, PHONE and TOOL sdes items are not entirely applicable.
I would suggest we use something that makes it easy to map the RTP stream to what it is used for. So on Abis, the BTS unit-id as well as the timeslot/sub-slot definitely should be encoded somehow to aid the mapping of RTP streams to physical GSM resources. The MSISDN is unfortunately not known to the BTS, so "PHONE" cannot reasonably be filled-in :(
Add a new osmo_rtp_set_source_desc() function to set the RTCP SDES items
This allows the users of libosmotrau to set the content of the SDES
items to something more useful than their compile-time defaults.
Put useful information in RTCP SDES.
The RTCP Sender Description is supposed to contain useful information
to identify the source of the RTP stream. So far, it only contained
compile-time default data of libortp. Let's put the BTS UnitID, the
lchan number and the OsmoBTS version in there.
This change requires libosmo-abis Change-Id Ice794f9e0c6caeea1c67520c12efbfa375d1fb82
#2 Updated by laforge about 3 years ago
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1 User Datagram Protocol, Src Port: 10351, Dst Port: 3334 Real-time Transport Control Protocol (Sender Report) Real-time Transport Control Protocol (Source description) [Stream setup by GSM A- (frame 15075)] 10.. .... = Version: RFC 1889 Version (2) ..0. .... = Padding: False ...0 0001 = Source count: 1 Packet type: Source description (202) Length: 20 (84 bytes) Chunk 1, SSRC/CSRC 0x318C8FD4 Identifier: 0x318c8fd4 (831295444) SDES items Type: CNAME (user and domain) (1) Length: 13 Text: email@example.com Type: NAME (common name) (2) Length: 23 Text: (bts=0,trx=0,ts=2,ss=0) Type: LOC (geographic location) (5) Length: 8 Text: 1234/0/0 Type: TOOL (name/version of source app) (6) Length: 21 Text: OsmoBTS-0.6.0.24-6bf9 Type: END (0)