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

[Philipp Hancke <[e-mail]>]

apologies for top-quoting...

We have run into an issue with Chrome/libWebRTC which does not support this particular case well.
Since it is very much an edge case I'd prefer (and I think Harald agrees with me) to reject the attempt to call setRemoteDescription.
This is more visible than an error while processing the RTP packets which we can't even bubble up to the API user.

cheers

Philipp

________________________________
Von: Christer Holmberg
Gesendet: Freitag, 16. Juni 2023 09:18
Bis: RFC Errata System; [e-mail]; [e-mail]; [e-mail]; [e-mail]; Francesca Palombini; Bo Burman; [e-mail]
Cc: Philipp Hancke; [e-mail]
Betreff: [EXTERNAL] RE: [MMUSIC] [Technical Errata Reported] RFC5576 (7544)

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 <[e-mail]> On Behalf Of RFC Errata System
Sent: Thursday, 15 June 2023 21.37
To: [e-mail]; [e-mail]; [e-mail]; [e-mail];
Francesca Palombini <[e-mail]>; Bo Burman
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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 <[e-mail]>

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:
-------------
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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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