Re: [MMUSIC] comments on draft-ietf-mmusic-sdp-g723-g729-03

[<[e-mail]>]

Hello

My answers inline
(I removed the agreed parts)

Aurelien

-----Message d'origine-----
De : Parthasarathi R [mailto:[e-mail]]
Envoyé : mercredi 3 juillet 2013 19:29
À : SOLLAUD Aurelien OLNC/OLN; [e-mail]; [e-mail] Objet : RE: comments on draft-ietf-mmusic-sdp-g723-g729-03

Hi Aurelien,

Sorry for the delay response. Thanks for the review comments. 

Please read inline.

Thanks
Partha

> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]]
> Sent: Thursday, June 27, 2013 1:52 PM
> To: [e-mail]; [e-mail]; [e-mail]
> Subject: comments on draft-ietf-mmusic-sdp-g723-g729-03
> 

  (snip)
> 
> 
> ** Section 3.1
> 
> 2)
> After the first paragraph, I suggest to insert the new paragraph below:
> 
> ---NEW
>  The Annex A of the codec concerns both sending and receiving, so both 
> sides of a bi-directional session MUST have the same setting.  If  one 
> party indicates that it does not support Annex A, Annex A  must be 
> deactivated both ways.
> -----
> That defines the general rationale of the following paragraphs.
>
<Partha> I agree with that it is the objective of this O/A requirement but how this statement qualifies for normative statement is not clear. From the offerer perspective, there is no control on same setting in both sides. In case you look at the combine requirements of this draft, this object is met.
</Partha>

[Aurelien] OK. I agree you can turn "MUST" into "must". I think this new paragraph helps anyway.

 
> 
> 3)
> -----
>    When the offer has G723 with annexa=no then the answer MUST NOT have
>    annexa=yes for G723.  Thus the annexa parameter can be turned off by
>    the answerer, but cannot be turned on.
> -----
> I don't think this new requirement is needed.
> Anyway implementation that will not implement this RFC-to-be will not 
> comply with it.
> 
<Partha> As per based G723 RFC, it is expected for all the implementation to support annexa. This issue is discussed in http://www.ietf.org/mail-archive/web/mmusic/current/msg11165.html </Partha> 

[Aurelien] Yes I agree all implementations support annexa. What I called the RFC-to-be is the document draft-ietf-mmusic-sdp-g723-g729. My comment was that previous implementations will not comply with this "MUST NOT". A warning should be written on this. The receiver of the SDP should be tolerant and ready to receive SDP not compliant with this new requirement, without breaking.
I the offer has annexa=no and the answer (of an old implementation) has annexa=yes, Annex A must not be used.
It is the same kind of thing you describe later about the case where the offer has annexa=no and the answer has no annexa at all. Annex A must not be used.


  (snip)
> 
> ** Section 3.2
> 
> 5)
> After the first two paragraphs, I suggest to insert the new paragraph
> below:
> 
> ---NEW
>  The Annex B of the codec concerns both sending and receiving, so both 
> sides of a bi-directional session MUST have the same setting.  If  one 
> party indicates that it does not support Annex B, Annex B must be 
> deactivated both ways.
> -----
> That defines the general rationale of the following paragraphs.
> 

<Partha> Same as comment 2 reply. I agree with that it is the objective of this O/A requirement but how this statement qualifies for normative statement is not clear. From the offerer perspective, there is no control on same setting in both sides. In case you look at the combine requirements of this draft, this object is met. </Partha>

[Aurelien] same as comment 2, you can keep it informative and turn the "MUST" into "must".


> 
> 6)
> -----
>    When the offer or answer has G729 and the annexb parameter is 
> absent,
>    it MUST be considered as if the offer or answer has G729 with
>    annexb=yes.
> -----
> This paragraph is redundant with what is said before.
> Remove it.
> 
> 

<Partha> As per based G729 RFC, it is expected for all the implementation to support annexb. This issue is discussed in http://www.ietf.org/mail-archive/web/mmusic/current/msg11165.html </Partha>

[Aurelien] You did not understand me. I said to remove the paragraph because it is an exact repetition of text. I quote the whole text:

----
   When the offer or answer has G729 and the annexb parameter is absent,
   the offerer or answerer knows that it has implied the default
   "annexb=yes".  This is because the annexb attribute is part of the
   original registration of audio/G729 [RFC4856].  All implementations
   that support G729 understand the annexb attribute.  Hence, this case
   MUST be considered as if the offer or answer has G729 with
   annexb=yes.

   When the offer or answer has G729 and the annexb parameter is absent,
   it MUST be considered as if the offer or answer has G729 with
   annexb=yes.
----

As you can see, the second paragraph says the exact same thing as the first one.


> 7)
> -----
>    When the offer has G729 with annexb=no then the answer MUST NOT have
>    annexb=yes for G729.  Thus the annexb parameter can be turned off by
>    the answerer, but cannot be turned on.
> -----
> I don't think this new requirement is needed.
> For the same reason as for G723
> 
<Partha> Same reply as comment 3. As per based G729 RFC, it is expected for all the implementation to support annexb. This issue is discussed in http://www.ietf.org/mail-archive/web/mmusic/current/msg11165.html </Partha>

[Aurelien] Same as comment 3, I suggest adding a warning on previous implementation that may not comply with this new requirement.

  (snip)

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