Re: [rtcweb] Fwd: New Version Notification for draft-alvestrand-mmusic-simulcast-ssrc-00.txt

Hi Harald,

Just one quick comment in case you find it useful.

I have been using this format for signaling both rids and ssrcs (and 
association between both):

a=simulcast:send c;b;a a=rid:c send ssrc=2564467881 a=rid:b send ssrc=1 
a=rid:a send ssrc=3 a=ssrc-group:FID 2564467881 32941417 
a=ssrc-group:FID 1 2 a=ssrc-group:FID 3 4 a=ssrc:2564467881 
cname:eRUkt2XxiSTlri77 a=ssrc:32941417 cname:eRUkt2XxiSTlri77 a=ssrc:1 
cname:eRUkt2XxiSTlri77 a=ssrc:2 cname:eRUkt2XxiSTlri77 a=ssrc:3 
cname:eRUkt2XxiSTlri77 a=ssrc:4 cname:eRUkt2XxiSTlri77

Note that the ssrc param (as a rid-param-other) in rid attribute is 
valid per the ABNF in:

https://tools.ietf.org/html/draft-ietf-mmusic-rid-15#page-19 
<https://tools.ietf.org/html/draft-ietf-mmusic-rid-15#page-18>

  rid-param = rid-width-param
                        / rid-height-param
                        / rid-fps-param
                        / rid-fs-param
                        / rid-br-param
                        / rid-pps-param
                        / rid-bpp-param
                        / rid-depend-param
                        / rid-param-other
  rid-param-other   = 1*(alpha-numeric / "-") [ "=" param-val ]
  param-val         = *( %x20-58 / %x60-7E ) ; Any printable character 
except semicolon

IMHO the usage of FID for signaling the "SIM" group is not a good choice 
as it is being used today for signaling the rtx association, and should 
be still present in the SDP if not using rids/rrids (which I understand 
that is the goal of the draft)

Best regards
Sergio

On 11/04/2019 12:30, Harald Alvestrand wrote:
>
> I have made a proposal.
>
> Note: This is strictly a *personal* contribution. Do not attach undue 
> authority to it.
>
>
> Harald
>
>
>
> -------- Forwarded Message --------
> Subject: 	New Version Notification for 
> draft-alvestrand-mmusic-simulcast-ssrc-00.txt
> Date: 	Thu, 11 Apr 2019 03:28:17 -0700
> From: 	internet-drafts@ietf.org
> To: 	Harald Alvestrand <harald@alvestrand.no>
>
>
>
>
> A new version of I-D, draft-alvestrand-mmusic-simulcast-ssrc-00.txt
> has been successfully submitted by Harald Alvestrand and posted to the
> IETF repository.
>
> Name: draft-alvestrand-mmusic-simulcast-ssrc
> Revision: 00
> Title: Using SSRC with WebRTC Simulcast
> Document date: 2019-04-11
> Group: Individual Submission
> Pages: 6
> URL: 
> https://www.ietf.org/internet-drafts/draft-alvestrand-mmusic-simulcast-ssrc-00.txt
> Status: 
> https://datatracker.ietf.org/doc/draft-alvestrand-mmusic-simulcast-ssrc/
> Htmlized: 
> https://tools.ietf.org/html/draft-alvestrand-mmusic-simulcast-ssrc-00
> Htmlized: 
> https://datatracker.ietf.org/doc/html/draft-alvestrand-mmusic-simulcast-ssrc
>
>
> Abstract:
> This document describes a convention for sending "a=ssrc" attributes
> in SDP together with "a=simulcast" attributes. This allows SFUs that
> need SSRC information to have this info easily accessible.
>
> Given that it is intended as an interim measure, it does not aim for
> being published as an RFC.
>
>
>
> Please note that it may take a couple of minutes from the time of 
> submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> The IETF Secretariat
>
>
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