Submission of draft-ietf-avt-rtp-text-00.txt to IETF

Mon Aug 30 10:41:15 EDT 1999

Hi Gunnar,

I believe we had this discussion before - And I still find no justification
to sending Text (which inherently must be lossless and is extreme low
using RTP.  Nothing stops us from opening an TCP channel using OLC/CLC
and sending text over it.  I agree - when lip-sync is required, TCP delay
(on average
1/3 for text chat type apps) may miss out a little, but I don't believe
that to be
such a big issue.

The main problem I see is that using RTP on average text typist means that
packets are going to be sent every 2-3 characters, and even with
redundancy, packetloss
can still occur which is unacceptable.

- gur

The document "RTP Payload for Text Conversation" is submitted to IETF-draft
as agreed in the avt wg in the IETF Oslo meeting. Comments are welcome to
the author at gunnar.hellstrom at or to the rem-conf at mail

This RTP payload is used by H.323 Annex G Text conversation and text SET


   This memo describes how to carry text conversation session contents
   in RTP packets. Text conversation session contents is specified in
   ITU-T Recommendation T.140 [1].

   Text conversation is used alone or in connection to other
   conversational facilities such as video and voice, to form multimedia
   conversation services.

   This RTP payload description contains an optional possibility to
   include redundant text from already transmitted packets in order to
   reduce the risk of text loss caused by packet loss. The redundancy
   coding follows RFC 2198.

Gunnar Hellstr
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Gunnar Hellstr?m
LM Ericsson

Tel +46 708 204 288 or +46 556 002 03
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