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Re: [AVT] draft-ietf-avt-rtp-speex-02.txt





On Thu, 21 Jun 2007, Colin Perkins wrote:

There shouldn't be any parameter definitions in the SDP usage section. That section is only used to specify how the media type parameters are represented in SDP.

The text you proposed seems fine to me: However, there is one point where you could probably help again.

Is it acceptable for section defining media type and parameters that
"mode" parameter can be specified several times? I wanted this to
be possible for SDP usage but I'm not sure it is authorized to allow
multiple "mode" to appear in section 4.1.1.

tks,
Aymeric

Having now had time to read the draft in detail, what's needed is something like:

 The information carried in the media type specification has a
 specific mapping to fields in the Session Description Protocol (SDP)
 [5], which is commonly used to describe RTP sessions.  When SDP is
 used to specify sessions employing the Speex codec, the mapping is
 as follows:

 o  The media type ("audio") goes in SDP "m=" as the media name.

 o  The media subtype ("speex") goes in SDP "a=rtpmap" as the encoding
    name. The required parameter "rate" also goes in "a=rtpmap" as the
    clock rate.

 o  The parameters "ptime" and "maxptime" go in the SDP "a=ptime" and
    "a=maxptime" attributes, respectively.

 o  Any remaining parameters go in the SDP "a=fmtp" attribute by
    copying them directly from the media type string as a semicolon
    separated list of parameter=value pairs.

 Some example SDP session descriptions utilizing Speex encodings
 follow.

To replace much of the existing text in the first half of Section 5. The rationale is that all parameters are defined as parameters of the media type, and the SDP usage just describes how those media type parameters are encoded into SDP.

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



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