Subject: WG Last Call on SDP

From: Mark Handley <[email-masked]>
Date: Wed, 02 Apr 1997 12:05:07 -0500

I'd like to issue a working-group last call on the current draft of
the Session Description Protocol (draft-ietf-mmusic-sdp-03.{txt,ps})
We plan to submit it to the IESG for Proposed Standard in about three
weeks time.

Mark

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From: Pete Cordell <[email-masked]>
Date: Thu, 3 Apr 1997 18:18:25 +0100

Mark,

Some comments on SDP:

1. I think the maximum line length ought to be specified as some value
or as unbounded.

2 .We have been looking at the a=cat field, and wanted to suggest that
users/organisations should register a top level label with IANA so that
their categorisations can be identified.  e.g. a TV station, say MTV,
could register mtv, which would allow them to have cat fields like:

a=cat:mtv.rock.heavy

To fit in with this scheme, users/organisations that didn't want to
register a top level category, could use x- notation, i.e.:

a=cat:x-mtv.rock.heavy

It may also be useful to allow for a digital signature at the end of the
line so that things like TV ratings could be signed.  This would
probably have to be based on a signature of everything minus the cat
lines.

Thanks,

Pete

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P.S. Although this should not affect the SDP RFC, we have also been
considering the following media encodings to give some hierarchy to SDP
announcements, and also allow some more attractive presentation of
information as per the TV times etc.  Hopefully the extensibility of SDP
will allow this and no action is required at this time.

m=sdp <port> <transport>
c=IN IP4 <IP dotted notation address>/<ttl>

and

m=embedded <MIME-type> <MIME-transfer-encoding> [<name>]
a=data:<encoded data>
a=.....

e.g.

m=sdp 127 sap
c=IN IP4 224.1.2.3/127

m=embedded application/html 7bit 
a=data:<html><body><img src="jurasic.gif">
a=data:<A HREF="hollywood.com/films/jurasic">Jurasic Park</A> was last
years big blockbuster and a great
a=data:success for director <A
HREF="hollywood.com/directors/spielberg">Steven Spielberg</A>.
a=data:</body></html>

m=embedded image/gif base64 jurasic.gif
a=data:akjhvgkjygkuekjhvbkdjhvbkjhg9763t9uyg9876tv976ds876t
a=data:oniuhbcd897y4b097yd097y4-98yd9-8y-9487y097yt0874
a=data:bt0987bn0

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Notice:  This contribution is the personal view of the author and does
not necessarily reflect the technical nor commercial direction of
British telecommunications plc.
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