Re: Genart Telechat review: draft-ietf-avtext-rtp-grouping-taxonomy-07

Robert Sparks <rjsparks@xxxxxxxxxxx> · Tue, 07 Jul 2015 13:34:01 -0500



    On 7/7/15 12:22 PM, Bo Burman wrote:

    
        Regarding
            your remaining nit:
        Am
            I interpreting you correctly that you are concerned with RTP
            streams that only sends RTCP, never anything else?
      
    
    Yes.

    
        We
            have two concepts in the draft that are affected by this;
            Source RTP Streams and Redundancy RTP Streams. If no RTP
            data is ever sent, how do we distinguish between an “empty”
            Source RTP Stream and an “empty” Redundancy RTP Stream?
      
    
    I'm not sure why you would need to. Maybe that's why I don't
    understand why you need the qualification in the first place?

    
        Would
            it be enough with a formulation saying that _if_ any
            RTP data is ever sent, a Source RTP Stream would take that
            from an Encoded Stream? Would that take care of your
            concern?
      
    
    Probably.

    
    Think of it this way - look at Figure 1 in the current draft.

    Consider an encoder that does silence suppression as a special case
    of VBR encoding, and the case I mention where silence suppression is
    constantly on, and the resulting bit rate is zero. Now, after
    encoding, and packetizing, you hit the new RTP-based Security boxes,
    which are configured through some magic to combat the known security
    issues with using VBR encodings by producing a constant rate output.
    You still want to talk about source streams in this case even if
    they're empty  - while there aren't packets going into that security
    box, there are lots of packets coming out.

    
    RjS

    
              From:
                  Robert Sparks [mailto:rjsparks@xxxxxxxxxxx]
                  

                  Sent: den 6 juli 2015 22:41

                  To: General Area Review Team; ietf@xxxxxxxx;
                  draft-ietf-avtext-rtp-grouping-taxonomy@xxxxxxxx;
                  avtext@xxxxxxxx

                  Subject: Genart Telechat review:
                  draft-ietf-avtext-rtp-grouping-taxonomy-07
            
          
          I am the assigned Gen-ART reviewer for this draft. For background on
            

            Gen-ART, please see the FAQ at 

            < http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
            

            Please wait for direction from your document shepherd 

            or AD before posting a new version of the draft. 

            
            Document: draft-ietf-avtext-rtp-grouping-taxonomy-07

            Reviewer: Robert Sparks

            Review Date: 6 Jul 2015

            IETF LC End Date: past

            IESG Telechat date: 9 Jul 2015

            
            Summary: Ready for publication as an Informational RFC

            
            Thanks for addressing the comments I made at LC.

            
            Very small nit:

            
            I still worry that with "at least some content ... at some
            point during its lifetime" that you are improperly excluding
            streams that may never send RTP packets (because of silence
            suppression or the way a codec works), when RTCP will be
            sent. This could happen in a multimedia situation where
            multiple microphones are signaled, but one just happens to
            never get used for example.