Re: [MMUSIC] SDP Directorate Review: draft-ietf-payload-rtp-h265-13.txt
"Ben Campbell" <ben@nostrum.com> Sun, 19 July 2015 10:34 UTC
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From: Ben Campbell <ben@nostrum.com>
To: draft-ietf-payload-rtp-h265@tools.ietf.org
Date: Sun, 19 Jul 2015 12:34:23 +0200
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Cc: Flemming Andreasen <fandreas@cisco.com>, payload-chairs@ietf.org, mmusic <mmusic@ietf.org>
Subject: Re: [MMUSIC] SDP Directorate Review: draft-ietf-payload-rtp-h265-13.txt
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Hi, Have I missed a response to Flemming's SDP review? Assuming that I haven't, can you comment on when you might be able to respond? If this requires a revision, it would be helpful to see the updates discussed via mail first. Thanks! Ben. On 12 Jun 2015, at 18:44, Flemming Andreasen wrote: > Hi > > I am the assigned SDP directorate reviewer for > draft-ietf-payload-rtp-h265 and I have reviewed the -13 version. For > background on the SDP directorate, please see the FAQ at > > > http://www.ietf.org/iesg/directorate/sdp.html > > > Please wait for direction from your document shepherd or AD before > posting a new version of the draft. > > > > Summary: > --------- > The document does not define any new SDP attributes and as such it > does not fall within the typical scope of SDP directorate reviews. The > document does however define a number of parameters for use in SDP in > the form of media format ("a=fmtp") parameters, including support for > these as source-specific parameters (per RFC5576). The review of the > document was performed to ensure that the "fmtp" parameters defined > are indeed reasonably defined as fmtp parameters and that they do not > interfere with other SDP related standards and design principles. > > Note that this review does not attempt to review the overall > specification for technical accuracy above and beyond the SDP-related > aspects described above. In particular, this review does not attempt > to evaluate the technical accuracy of the fmtp-parameters defined as > this requires more detailed H.265 knowledge and falls under the scope > of the PAYLOAD WG. > > From an SDP point of view, and as the document notes in Section 4.3, > there are interactions between the "multiple RTP streams over a single > Media Transport (MRST)" mode defined and the Standards Track Bundle > mechanism currently being defined in MMUSIC > (seehttp://datatracker.ietf.org/doc/draft-ietf-mmusic-sdp-bundle-negotiation/). > From a signaling point of view, this overlap manifests itself in the > form of the tx-mode fmtp parameter defined for the different > transmission modes in Section 7.1. It would be highly desirable to > clarify this overlap and provide procedures for how to deal with any > inconsistencies between the two. > > Another general comment is the lack of an overall grammer for the set > of parameters. There is only a grammar for one of the parameters > (namely dec-parallel-cap); an overall grammer covering all the > parameters would be highly desirable. > > Other than that (and a few more detailed comments below), there are no > significant SDP-related issues with the document. > > > > Detailed comments: > ------------------- > 1) Section 7.2.2: > <quote> > o The capability parameters max-lsr, max-lps, max-cpb, max-dpb, > max-br, max-tr, and max-tc MAY be used to declare further > capabilities of the offerer or answerer for receiving. These > parameters MUST NOT be present when the direction attribute is > "sendonly". > > o The capability parameter max-fps MAY be used to declare lower > capabilities of the offerer or answerer for receiving. The > parameters MUST NOT be present when the direction attribute is > "sendonly". > </quote> > > It is unclear why these parameters are not allowed in either the offer > or the answer as the "sendonly direction attribute would seem to make > them relevant in at least one direction (unless the direction > attribute specifically applies to the SDP being sent and not the > overall media stream, which is not entirely clear based on the > wording). > > 2) Section 7.2.2 also describes how the same payload type number needs > to be used in the offer and the answer. To be clear, this restriction > can only be applied to payload type numbers used for H265 and hence > does not affect offer/answer procedures for any other media formats. > The text should be updated to clarify this point (e.g. in the bullet > that begins with "The same RTP payload type number used in the offer > MUST be used in the answer when the answer includes > recv-sub-layer-id") > > > Thanks > > -- Flemming > > _______________________________________________ > mmusic mailing list > mmusic@ietf.org > https://www.ietf.org/mailman/listinfo/mmusic
- [MMUSIC] SDP Directorate Review: draft-ietf-paylo… Flemming Andreasen
- Re: [MMUSIC] SDP Directorate Review: draft-ietf-p… Ben Campbell