Re: [MMUSIC] Bundle and "m=" line terminology [Re: Review of draft-ietf-mmusic-sdp-bundle-negotiation-32 (Part I)]

[Flemming Andreasen <[e-mail]>]

On 11/7/16 11:08 AM, Eric Rescorla wrote:
>
>
> On Mon, Nov 7, 2016 at 1:52 AM, Christer Holmberg 
> <[e-mail] 
> <mailto:[e-mail]>> wrote:
>
>     Hi,
>
>     As Ekr said, the issue is not “m= line” versus “media
>     description”. It’s more whether e.g., an SDP attribute belongs to
>     a media description, is within a media description, or is
>     associated with a media description/m- line.
>
>     The reason I use “associated” is because I have many times been
>     told that an attribute is not part of a media description/m- line
>     (compared to e.g., the port and proto value).
>
>
An attribute can indeed be part of a media description, however it 
cannot be part of an "m=" line.

> I had understood the difference between m= line and media description 
> to precisely be that the media description contained the attributes 
> and the m= line did not.
>
Exactly.

-- Flemming


> -Ekr
>
>     Regards,
>
>     Christer
>
>     From: Eric Rescorla <[e-mail] <mailto:[e-mail]>>
>     Date: Sunday 6 November 2016 at 21:01
>     To: Flemming Andreasen <[e-mail]
>     <mailto:[e-mail]>>
>     Cc: Christer Holmberg <[e-mail]
>     <mailto:[e-mail]>>, "[e-mail]
>     <mailto:[e-mail]>" <[e-mail] <mailto:[e-mail]>>
>     Subject: Re: Bundle and "m=" line terminology [Re: [MMUSIC] Review
>     of draft-ietf-mmusic-sdp-bundle-negotiation-32 (Part I)]
>
>
>
>     On Thu, Nov 3, 2016 at 8:31 PM, Flemming Andreasen
>     <[e-mail] <mailto:[e-mail]>> wrote:
>
>
>         Christer reminded me to pick up the part below:
>
>
>         On 10/3/16 10:00 AM, Eric Rescorla wrote:
>>
>>
>>         On Mon, Oct 3, 2016 at 4:01 AM, Christer Holmberg
>>         <[e-mail]
>>         <mailto:[e-mail]>> wrote:
>>
>         <snip>
>>
>>                 >S 10.3.1.1.
>>
>>                 >   When an offerer generates an initial offer, the
>>                 offerer MUST
>>
>>                 >   associate either an SDP 'rtcp-mux' attribute
>>                 [RFC5761] or an SDP
>>
>>                 > 'rtcp-mux-only' attribute
>>                 [I-D.ietf-mmusic-mux-exclusive] with each
>>
>>                 >   bundled RTP-based "m=" line in the offer.  The
>>                 offerer MUST associate
>>
>>                 >   an SDP 'rtcp-mux-only' attribute with each
>>                 bundle-only "m=" line.  If
>>
>>                 >   the offerer associates a 'rtcp-mux-only' attribute
>>                 with an "m=" line,
>>
>>                 >   the offerer may also associate a 'rtcp-mux'
>>                 attribute with the same
>>
>>                 >   "m=" line, as described in
>>                 [I-D.ietf-mmusic-mux-exclusive].
>>
>>                 >
>>
>>                 > This is a particularly egregious case of associate
>>                 disease that could
>>
>>                 > be easily solved by using "add" when referring to
>>                 the attributes
>>
>>                 > you put in the m= section.
>>
>>                 People have previously said that you don’t “add”
>>                 attributes to m- lines: you add port values etc, but
>>                 not attributes.
>>
>>                 This is an example of where I’ve had to re-write big
>>                 parts of the documents a number of times already,
>>                 because every time someone else reads the document
>>                 he/she is not happy with the terminology. I just
>>                 don’t want to do it again.
>>
>>
>>             The terminology that JSEP uses is that "m= sections"
>>             include attribute lines.
>>
>>             I think this is a lot clearer.
>>
>>              I don’t personally disagree, but there are people that
>>             have had other opinions.
>>
>>              In general I think it would be really useful to have
>>             common terminology in BUNDLE and JSEP, but I don’t want
>>             to re-write the document once again, and then later be
>>             told to do it again…
>>
>>
>>         Resolving the appropriate terminology seems like a chair issue.
>>
>         RFC 4566 (SDP) Section 5 makes it pretty clear that a Media
>         Description consists of an "m=" line optionally followed by a
>         number of other lines (typically attribute lines). In other
>         words, an "m=" line and a media description is generally not
>         synonymous.
>
>         Earlier versions of bundle did not reflect that distinction
>         properly, and about a year ago, I asked for the terminology to
>         be aligned with RFC 4566. There were a few off-list comments
>         from other people that agreed with that view and the draft got
>         updated accordingly (as of -24). That is what the current
>         bundle draft does and I continue to believe that is what it
>         should do.
>
>
>     This message leaves me extremely puzzled because I'm not saying
>     otherwise, and that's why JSEP uses "m= section" for this concept.
>     Media description would also be fine. What is problematic is the
>     use of "associated with an m= line" to mean "part of a media
>     description" or "part of an m= section". That text is extremely
>     confusing, especially when the word "associated" is used in a
>     number of other concepts. So, what I'm asking for is one of the
>     alternative terms I list here.
>
>     -Ekr
>
>
>         Thanks
>
>         -- Flemming (with chair hat on)
>
>
>
>>         -Ekr
>>
>>
>>             Regards,
>>
>>             Christer
>>
>>
>>
>>
>>
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>