Re: [AVTCORE] WGLC on draft-ietf-avtcore-idms-05

Roni,

I have some comments on this draft:

- I don't believe RTCP is on the RFC Editor's list of approved acronyms for document titles, but RTP is, so I suggest changing the title of the draft to "Inter-destination Media Synchronisation Using the RTP Control Protocol (RTCP)".

- Acronyms also need expanding on first use in the abstract.

- Editorial: the draft might read better if the Section 1.1 heading were removed, and if sub-sections 1.2, 1.3, and 1.4 were made part of a new Section 2 "Rationale".

- Editorial: in Section 1.2, "scalable to large multicast networks" may be better phrased "scalable to large groups" since the functionality is not multicast specific.

- Section 3, near the end of page 6, the draft says "...when both Alice and Bob received (or played out) a particular RTP packet". This might be clearer written "when both Alice and Bob received (and, optionally, when they played out) a particular RTP packet". 

- Section 3 doesn't seem to mention that Alice and Bob need synchronised clocks for this to work. It probably should.

- I find the justification for using a 32 bit NTP presentation timestamp in Section 6, but a 64 bit NTP presentation timestamp in Section 7 to be unconvincing. Could you either strengthen the justification, or move to a common size?

- Section 6: is the PT field needed? The combination of RTP timestamp and SSRC should identify a packet, even with changes in PT and clock rate.

- Section 6, penultimate paragraph: "...in which a certain RTP timestamp shows up for the first time" is problematic, since the RTP timestamp can wrap. 

- Section 8: "receiver involved need synchronised clocks" - yes, but be clear what clock needs to be synchronised. The RTP-format media clocks don't need to be synchronised, for example, while the NTP-format clock does.

- Section 8, 3rd paragraph: is the use of the mechanism in draft-williams-avtcore-clksrc mandatory? It would be useful to make an RFC 2119 style recommendation here.

- Section 8, last paragraph: should "...is therefore recommended to take the guidelines..." be "...RECOMMENDED..."?

Colin

On 17 Jun 2012, at 17:04, Roni Even wrote:
> Hi,
> I would like to start a WGLC on http://tools.ietf.org/html/draft-ietf-avtcore-idms-05 , RTCP for inter-destination media synchronization.
>  
> The WGLC will end on July 10th, 2012
>  
> Please review the draft and send comments to the list.
>  
> For the draft authors;  Are you aware of any IPR that applies to draft-ietf-avtcore-idms-05? If so,
> has this IPR been disclosed in compliance with IETF IPR rules (see RFCs 3979, 4879, 3669 and 5378 for more details)?
> The above question is needed for the document write-up when sent to publication.
>  
> Thanks
>  
> Roni Even
> AVTcore  co-chair
>  
> _______________________________________________
> Audio/Video Transport Core Maintenance
> avt@ietf.org
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-- 
Colin Perkins
http://csperkins.org/