Re: [rtcweb] Does RID require the same ext id for all the m= sections?

Aliases are already restricted in same m-line by the header extension RFC.

Best regard
Sergio
On 11/09/2017 17:02, Mo Zanaty (mzanaty) wrote:
> Bundle defines MID, and section 13 restricts all extmap IDs (including 
> MID, RID, etc.) to be consistent across all bundled m= sections, just 
> like PTs. I see no restriction against aliases, nor any reason to 
> impose one.
>
> Mo
>
> From: Iñaki Baz Castillo <ibc@aliax.net <mailto:ibc@aliax.net>>
> Date: Monday, September 11, 2017 at 9:52 AM
> To: mzanaty <mzanaty@cisco.com <mailto:mzanaty@cisco.com>>
> Cc: "rtcweb@ietf.org <mailto:rtcweb@ietf.org>" <rtcweb@ietf.org 
> <mailto:rtcweb@ietf.org>>
> Subject: Re: [rtcweb] Does RID require the same ext id for all the m= 
> sections?
>
> Ok, but that is not valid for MID, as the reveiver transport is 
> supposed to check the MID value using a single extmap ID, right?
>
> El 11 sept. 2017 3:34 p. m., "Mo Zanaty (mzanaty)" <mzanaty@cisco.com 
> <mailto:mzanaty@cisco.com>> escribió:
>
>     See bundle section 13.
>
>     https://tools.ietf.org/html/draft-ietf-mmusic-sdp-bundle-negotiation-38#section-13
>     <https://tools.ietf.org/html/draft-ietf-mmusic-sdp-bundle-negotiation-38#section-13>
>
>     The same ID must always map to the same URN. Different IDs can map
>     to the same URN as aliases. (The latter is not stated but implied.)
>
>     Mo
>
>     On Sep 11, 2017, at 8:49 AM, Iñaki Baz Castillo <ibc@aliax.net
>     <mailto:ibc@aliax.net>> wrote:
>
>     On Sun, Sep 10, 2017 at 8:22 PM, Mo Zanaty (mzanaty)
>     <mzanaty@cisco.com <mailto:mzanaty@cisco.com>> wrote:
>>     All extmap IDs must be consistent in all bundled m= sections,
>>     just like PTs.
>
>     Thanks.
>
>     However, what does "consistent" mean? I assume/expect that the extmap
>     ID (for example a=extmap:4) cannot exist in two different m= sections
>     pointing to different extension URLs, right?
>
>     But, and given that you told about PTs, it's perfectly valid that two
>     different PTs point to the same codec+condiguration within the same m=
>     section or in different m= sections.
>
>     So, could a m=audio section have an "a=extmap:4 urn:foo" line while a
>     m=video section has "a=extmap:8 urn:foo"? or should both use extmap ID
>     4?
>
>     For example, the extmap ID for MID must be *UNIQUE* across all the
>     m=sections. Does the same constrain exist for the extmap ID for RID?
>
>
>
>     -- 
>     Iñaki Baz Castillo
>     <ibc@aliax.net <mailto:ibc@aliax.net>>
>
>
>
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