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Re: [MMUSIC] WGLC: draft-ietf-mmusic-rfc2326bis-22
Thomas Schierl skrev:
> Dear authors,
>
> I have one question, which came into my mind reading Appendix D.
>
> In section D.1.2, I read "
>
> Usage of grouping of media lines [RFC3388 <http://tools.ietf.org/html/rfc3388>] to determine which media
> lines should or should not be included in a RTSP session is
> unspecified.
>
> "
>
> Earlier in the Appendix, I read "
>
> However
> ,the SDP extension "Grouping of Media Lines in the Session
> Description Protocol (SDP)" [RFC3388 <http://tools.ietf.org/html/rfc3388>] may provide such functionality
> depending on need. Also future grouping semantics may in the future
> be developed.
>
> "
>
>
> What does it mean? Is SDP grouping allowed to be used with this spec?
> If not, then there might be an issue with respect of using the RFC 5583
> decoding dependency signaling required for multi flow transmission of
> layered codecs such as SVC.
>
>
I guess we need to clarify this. Grouping of media lines will require
that one understands the semantic that is used. But from an RTSP point
of view most semantics would be easy to incorporate as long as they
describe the relationship between media streams that you all most
receive. If any semantic would be more in the context of alternatives or
play only one at the time that creates also interaction with RTSP. I
think we can add text to clarify that it is required to understand the
semantics, and define what to do with the known semantics.
Cheers
Magnus Westerlund
IETF Transport Area Director
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