[MMUSIC] Comments/nits on draft-ietf-mmusic-sdp-media-capabilities-03.txt

["Ingemar Johansson S" <ingemar.s.johansson at ericsson.com>]

Hi

Some comments/nits on the draft:

==========
In general
"AMR/16000/1" should be replaced by "AMR-WB/16000/1" according to http://www.iana.org/assignments/media-types/
"AMR/8000/1" is correct however

==========
Page 8:
The example :
             a=tcap:1 RTP/SAVP
..
             a=pcfg:3 m=4 t=2 pt=4:18

Makes me believe that the tcap line should be something like

             a=tcap:1 RTP/SAVP RTP/AVP

or as an alternative "t=2" should be removed from the "a=pcfg:3" line

==========
A comment on section 3.3.3 (mscap)
This attribute makes it possible to formulate SDP's like 
m=audio 4321 RTCP/AVP ...
...
a=mcap:1 AMR
a=mcap:2 telephone-event
a=mscap:1 sendrecv
a=mscap:2 sendonly
...

It may be troublesome however to formulate the 1st answer SDP and the 2nd pass offer/answer. As a "plain SDP" cannot do this. Is there a way to solve this issue or should similar tricks be forbidden?. This problem is BTW formulated in 
http://www.3gpp.org/ftp/tsg_sa/WG4_CODEC/TSGS4_47/Docs/S4-080027.zip
I believe that this extra liberty in SDPCapNeg+SDPMedCapNeg can yield some interop issues unless they are addressed (perhaps they are, I'm a slow reader).

Regards
Ingemar
*******************************************
Ingemar Johansson
Senior Research Engineer, IETF "nethead"
EAB/TVP - Multimedia Technologies
  Ericsson Research Ericsson AB
  Box 920 S-971 28 Luleå, Sweden
Tel: +46 (0)8 4043042
ECN: 850-43042
ECC: 850-43074
Mobile: +46 (0)730 783289
*******************************************
  


_______________________________________________
mmusic mailing list
mmusic at ietf.org
https://www.ietf.org/mailman/listinfo/mmusic