[AVT] draft-ietf-avt-tfrc-profile-03.txt - imbed feedback in RTP?

[Jim Kleck <jimk at 8x8.com>]

The draft-ietf-avt-tfrc-profile-03.txt is specifically restricted to 
unicast,
and specifies feedback possibly once per data packet. This can generate
too much feedback traffic in the case of one-to-one video conferencing
(which typically operates at 64K - 512K bps). However, this case offers
a ready feedback path with much less overhead: the data pkts coming from
the far end. An additional extension to the RTP hdr could possibly add
the feedback at a small cost. The challenges with this scheme are:

- there is an implicit tie between the Tx and Rx RTP sessions, but in
 a one-to-one video conference that should not be too hard to formalize

- if the app does not recv any data pkts from the farend for a while then
 there will be no feedback, that could mean the far end has nothing to send
 (in which case a noop RTP pkt with the feedback could be specified,
 see draft-wing-avt-rtp-noop-01.txt, with no worries about using extra
 bandwidth because the lack of data makes that bandwidth available...
 or use the suggested Receiver Report extensions), or it could mean that
 there is some network problem


Does this seem worth further investigation?

Jim Kleck
8x8, Inc


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