Re: [MMUSIC] Mux Category and RFC4566bis

[Paul Kyzivat <[e-mail]>]

On 8/9/19 2:07 PM, Christer Holmberg wrote:
> Hi Paul,
> 
>>     Upon looking further at mux-attributes, perhaps it is a more likely
>>     candidate to reference criteria for new parameter values. In particular,
>>     section 4 (SDP Attribute Analysis Framework) comes close to serving the
>>     purpose.
>    
> I agree. When one defines a new attribute, one needs to read the semantics of the mux categories, and pick the one that fits the new attribute. I am not sure what else could be said regarding "how to choose a category".

Me either. But if an expert were charged with approving a new attribute, 
what criteria would he use for deciding if the mux category was "right"? 
Is the answer just "IESG review"?

>    
>>     I have a concern about it as it stands: this section only talks about
>>     *attributes*. But mux categories apply to many SDP parameters other than
>>     attributes. I *think* this is perhaps just sloppy terminology, and it is
>>     intended to apply more generally to parameters that are affected by mux
>>     category.
>    
> What other SDP parameters than attributes and b= do you think it applies to?

mux-attributes updates a whole bunch of parameter registries. Other than 
the actual attribute registries, none of them *are* attributes. Many of 
them are carried in a field in a value of some attribute, but that is 
different from them *being* an attribute.

> As far as calling b= an attribute is concerned, RFC 3556 actually DOES call it an attribute (see e.g., Section 2). Same thing for RFC 3890 (see e.g., section 1.1).
> 
> So, perhaps we could add some text to RFC4566bis saying that b= is often referred to as an attribute?

It may be that the most practical fix is to put some explanation 
somewhere in 4566, even though that is probably not the most ideal way. 
I'm groping for how to do that.

I guess I'll try to come up with something, but then I'll need others to 
review whether I've succeeded in being clear.

I'm wondering whether it might actually make sense to create another 
document that factors the Mux Category *framework* out from the specific 
analysis for preexisting values. It would have more in the way of 
guidance on how to choose. And maybe it could also consider what needs 
to be done in the future when another SDP parameter is defined that has 
interactions with bundle. (Can we do an update to a document that hasn't 
yet made it to RFC?)

	Thanks,
	Paul