If my memory serves me right, the "codepoints" of 4 for G.723.1 and 18 for G.729 were added to H.225.0 a while ago to reflect text in the revised RFC 1890 mentioned by Steve Casner. At one point, the payload format descriptions also matched, but I haven't compared the 2 documents lately to see if that is still the case.
Glen
Stephen Casner wrote:
On Wed, 23 Feb 2000, Chip Sharp wrote:
At 01:11 PM 2/23/00 -0800, Hutton, Charles wrote:
I have the same concerns for G.729E.
I'd recommend that as SG16 defines new encoding types that it register them with IANA.
Theoretically, someone could register your codepoints for a different algorithm.
No. As I mentioned in my previous response, the registration policy has been revised. There will be no more assignments of static payload type numbers because mechanisms are now in place in various control protocols to dynamically define payload type number bindings for each session. It should be clear that static assignments cannot continue indefinitely in a small number space. This rationale is explained further in section 3 of the draft revision of RFC 1890, which is
http://www.ietf.org/internet-drafts/draft-ietf-avt-profile-new-08.txt
My understanding is that H.245 provides a means to define dynamic payload types as part of the capability exchange using OIDs. This is necessary for non-standard encodings, for example. It should be used for future standard encodings as well to dynamically map from a larger encoding name space to the small payload type number space.
In addition to whatever namespace(s) may be needed for ITU protocols, several IETF protocols use the MIME namespace, including the "rtpmap" attribute used for dynamic payload type mapping in SDP. A few weeks ago, the IETF AVT working group sent a liaison statement to SG16 (or at least attempted to) via Joerg Ott to the Rapporteur of ITU SG16 Q.13 to describe the procedure for defining new RTP payload formats. In particular, we encourage the registration of new payload formats in the MIME namespace according to the procedures in
http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-mime-01.txt
I don't know the details of G.729E. If it requires a different payload format than G.729, then I would encourage you to let AVT review the payload format specification and that you register the payload format in the MIME namespace. -- Steve
-- Glen Freundlich ggf@lucent.com Lucent Technologies office: +1 303 538 2899 11900 N. Pecos fax: +1 303 538 3907 Westminster, Colorado 80234 USA