H.323 Annex I

Adam Li adamli at icsl.ucla.edu
Mon Feb 5 19:47:25 EST 2001

Dear Mr. Baese, and Q.3 experts,

First, since I haven't got Mr. Baese's opinion on what we pointed out in the
last email, I would like to repeat one more time and seeking a definite
answer (i.e., agree or disagree with your reasons).

For the following in the testing condition documents "When the Annex K
and/or Annex V is used, the length of the slice should be such to make
packets fit in the length of segment to avoid segmentation of the IP packet
(for fixed segment-loss-rate channels, see below)."

The reason for it:

If one want to evaluate if a protection scheme works, s/he need to show how
much the performance improves between the cases "with" and "without" the
proposed scheme. For a realistic measurement of the gain, the benchmark
performance in the "without" case that one compared to needs to be the
(near) optimal scenario. In other word, to demonstrate effectiveness of any
scheme, one need to show that it can provide any gain over the *best* case
the system has without it.

I think Mr. Baese agrees that use the right video slice length to avoid
segmentation gives the (near) optimal performance for the case *without* any
protection. Those annexes are in the mobile profile for a reason. That is
the benchmark case that both of our proposals need to be compared to. This
requirement is a fair condition and is not in favor of either proposal.

Mr. Baese wrote:

> it is quite discouraging that our questions remaining
> unanswered and the positive signs we were sending are
> ignored still.

All the email correspondence between Mr. Baese and me are on the email
reflector, so everyone knows what is going on.

It is strange to me that my explaination and reasoning for the testing
condition gets no technical answers and is met with reactions from Mr. Baese
such as above. I believe that we are here in ITU to discuss technical issues
and to design the best technical solutions that works, not politics.

Mr. Baese, could you give me just your comments on my on the slice length
(agree or disagree) with technical reasons?


Adam Li

Adam H. Li
Image Communication Lab                    (310) 825-5178 (Lab)
University of California, Los Angeles      (310) 825-7928 (Fax)

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