Subject: [MMUSIC] fmtp specific configuration vs parameters

From: Marc Petit-Huguenin <[email-masked]>
Date: Wed, 05 Feb 2014 10:47:42 -0700

RFC 3264 section 6.1:

  "The interpretation of fmtp parameters in an offer depends on the
   parameters.  In many cases, those parameters describe specific
   configurations of the media format, and should therefore be processed
   as the media format value itself would be.  This means that the same
   fmtp parameters with the same values MUST be present in the answer if
   the media format they describe is present in the answer.  Other fmtp
   parameters are more like parameters, for which it is perfectly
   acceptable for each agent to use different values.  In that case, the
   answer MAY contain fmtp parameters, and those MAY have the same
   values as those in the offer, or they MAY be different.  SDP
   extensions that define new parameters SHOULD specify the proper
   interpretation in offer/answer."

I am not sure I understand this paragraph.  It seems to say that there is fmtp
parameters that must be the same in the Offer and in the Answer, and some that
can be different.  But I went through the definition of 50 or so codecs, and
cannot find one fmtp parameter that is be required to be identical on both SDPs.

Can someone tell me if my understanding is correct, and if it is the case,
give me an example of parameter that must be identical on both sides?

Thanks.

- -- 
Marc Petit-Huguenin
Email: [email-masked]
Blog: http://blog.marc.petit-huguenin.org
Profile: http://www.linkedin.com/in/petithug