Re: [AVT] I-D ACTION:draft-ietf-avt-rtp-speex-01.txt

[Colin Perkins <csp at csperkins.org>]

On 12 Jun 2007, at 17:03, Aymeric Moizard wrote:
> On Tue, 12 Jun 2007, Colin Perkins wrote:
...
> > Section 5: the "a=fmtp:" attribute is for media type parameters  
> > only. If you wish to define vbr, cng, and mode parameters, they  
> > must be defined as media type parameters in the IANA  
> > considerations, and then mapped into the "a=fmtp:" line. Section  
> > 6.2 of RFC 4749 is a good example of how to do this.
>
> But that's definitly what is being said in section 5: in the following
> text, we wanted to inform that you MUST use a=fmtp for mode, vbr  
> and cng:
>
>    An other way to make recommendations to the remote Speex encoder is
>    to use its specific parameters via the a=fmtp: directive.  The
>    following parameters are defined for use in this way:
>
> Would you advise to change it to this text?:
>
>    An other way to make recommendations to the remote Speex encoder is
>    to use its specific parameters via the a=fmtp: directive.  "mode",
>    "cng" and "vbr" parameter MUST be specified using this  
> directive. The
>    parameters are defined for use in this way:
>
> As I understand your comment, you mean that "mode", "vbr" and "cng"  
> should
> appear in the section "4.1.1.  Registration of media type audio/ 
> speex"? Right?

The problem is that this sounds, due to "An other way to make  
recommendations", that the "a=fmtp:" parameters are different from  
the media type parameters. In fact the "a=fmtp:" line is an encoding  
of (some of) the media type parameters. All the parameters should be  
listed in the media type registration for audio/speex, and the  
section on SDP usage should explain how to code those in "a=fmtp:"  
and/or other SDP attributes, rather than defining new parameters.

Cheers,
--
Colin Perkins
http://csperkins.org/



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