Re: [MMUSIC] [Technical Errata Reported] RFC5576 (7544)

Not sure what the semantics would be. Ultimately, the grouping framework should not try to prescribe the semantics of its interpretation, and one could possibly create a use case where the same ssrc-id might appear multiple times. For the present ones, it doesn’t seem to maske sense.

Not sure that any action is needed.

Jörg

Sent from my iPad

> On 16. Jun 2023, at 09:18, Christer Holmberg <christer.holmberg@ericsson.com> wrote:
> 
> Why would someone use something like a=ssrc-group:FID 1234 1234? And, even if 
> someone does, what error would it cause?
> 
> Also, we don't have similar text for e.g., the SDP group attribute.
> 
> Regards,
> 
> Christer
> 
> 
> -----Original Message-----
> From: mmusic <mmusic-bounces@ietf.org> On Behalf Of RFC Errata System
> Sent: Thursday, 15 June 2023 21.37
> To: jonathan@vidyo.com; jo@acm.org; ts@thomas-schierl.de; superuser@gmail.com; 
> Francesca Palombini <francesca.palombini@ericsson.com>; Bo Burman 
> <bo.burman@ericsson.com>; fandreas@cisco.com
> Cc: phancke@microsoft.com; mmusic@ietf.org; rfc-editor@rfc-editor.org
> Subject: [MMUSIC] [Technical Errata Reported] RFC5576 (7544)
> 
> The following errata report has been submitted for RFC5576, "Source-Specific 
> Media Attributes in the Session Description Protocol (SDP)".
> 
> --------------------------------------
> You may review the report below and at:
> https://www.rfc-editor.org/errata/eid7544
> 
> --------------------------------------
> Type: Technical
> Reported by: Philipp Hancke <phancke@microsoft.com>
> 
> Section: 4.2
> 
> Original Text
> -------------
> Every <ssrc-id> listed in an "ssrc-group" attribute MUST be defined by a 
> corresponding "ssrc:" line in the same media description
> 
> Corrected Text
> --------------
> Every <ssrc-id> listed in an "ssrc-group" attribute MUST be defined by a 
> corresponding "ssrc:" line in the same media description and MUST appear only 
> once in this ssrc-group
> 
> Notes
> -----
> The goal is to clarify that something like
>  a=ssrc-group:FID 1234 1234
> is not valid. While this is demuxable (in the BUNDLE sense) it would require 
> chaining of ssrc-demuxing and payload type demuxing which is a lot of 
> complexity.
> The uniqueness is already implied by the following sentence (emphasis is 
> mine):
>   The SDP media attribute "ssrc-group" expresses a relationship among 
> *several* sources of an RTP session earlier in the section.
> 
> Instructions:
> -------------
> This erratum is currently posted as "Reported". If necessary, please use 
> "Reply All" to discuss whether it should be verified or rejected. When a 
> decision is reached, the verifying party can log in to change the status and 
> edit the report, if necessary.
> 
> --------------------------------------
> RFC5576 (draft-ietf-mmusic-sdp-source-attributes-02)
> --------------------------------------
> Title               : Source-Specific Media Attributes in the Session 
> Description Protocol (SDP)
> Publication Date    : June 2009
> Author(s)           : J. Lennox, J. Ott, T. Schierl
> Category            : PROPOSED STANDARD
> Source              : Multiparty Multimedia Session Control RAI
> Area                : Real-time Applications and Infrastructure
> Stream              : IETF
> Verifying Party     : IESG
> 
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