Subject: [SIP] SIP/SDP attribute under......

From: "rahul pande" <[email-masked]>
Date: Thu, 05 Oct 2000 09:06:29 IST

Hello All,
    I am having problem in understanding the "a=fmtp:" attribute, i haave 
tried to contact the [email-masked], but no one responds. The problem is 
somewhat related to SIP and other tools also which will be using SDP.
    SDP rfc2327 says ::

   "a=fmtp:<format> <format specific parameters>
       This attribute allows parameters that are specific to a
       particular format to be conveyed in a way that SDP doesn't have
       to understand them.  The format must be one of the formats
       specified for the media.  Format-specific parameters may be any
       set of parameters required to be conveyed by SDP and given
       unchanged to the media tool that will use this format. "

Sir, above whom is the rfc refering to as a "media tool"
    Secondly sir,
             Its clear that the SDP parsers don't have to worry about the 
<format specific parameters>, but who is going to handle the parseing of 
this parameter, since PINT, RTP payload types and others are having 
different grammar for <format specific parameter>.

Can someone please give me some details reguerding this or please do refer 
me a URL.
   Thanking  you,
       rahul

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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 6 Oct 2000 17:52:23 -0400

The original usage of SDP was in mbone tools where you had a directory tool
(namely, SDR), which would receive SAP advertisements of sessions encoded in
SDP. If you clicked on a session, it would start tools (like vat, nevot,
nevit, vic, rat) which could handle the media streams described in the
session. So, what this text means is that in this application, the session
directory tool would not parse the fmtp parameter, since it is ignorant of
media details.

In applications where there is no distinction between the tool parsing the
SDP and the tool using the SDP for media streams, of course the code using
the SDP would need to parse it fully.

-Jonathan R.

---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com

> -----Original Message-----
> From: rahul pande [mailto:[email-masked]]
> Sent: Thursday, October 05, 2000 5:06 AM
> To: [email-masked]
> Subject: [SIP] SIP/SDP attribute under......
> 
> 
> Hello All,