Subject: Re: Can pure datagrams really service real-time applications?

From: Simon E Spero <[email-masked]>
Date: Mon, 28 Mar 94 11:57:21 -0500

>>>>> "Jon" == Jon Crowcroft <[email-masked]> writes:

    Jon> a video compression scheme is scene dependneent - should a
    Jon> user look at the shirt they are wearing before bookingthe
    Jon> network call.

*ANY* sheme which penalises obnoxious shirts has got to be worthwhile

---

From: Valdis Kletnieks <[email-masked]>
Date: Mon, 28 Mar 94 12:54:19 EST

>*ANY* sheme which penalises obnoxious shirts has got to be worthwhile

Today, I'm wearing a sedate Levi's Docker shirt, which is a dark blue and
light blue plaid.  Most definitely NOT obnoxious.  However, the plaid is
going to play hell with most attemts at compression.  Unless the algorithm
is smart enough to compress the fact that there are 16 vertical stripes
of alternating widths and colors every 2 inches - even when the shirt is
looking somewhat rumpled due to lack of ironing.

On the other hand, the violently orange tshirt I was wearing Saturday while
playing lumberjack in my backyard would compress very well:

repeat 2 zillion times *BRIGHT ORANGE*.

There is also the issue of artifacts created by the television scanning
technology - as anybody who has seen a news anchorperson's shirt suddenly
explode into a Moire pattern when he moves 3 millimeters left can testify.
Suddenly, the shirt goes from being one color all over to a patchwork of
different colors (at least as seen by the camera).  Do current compression
schemes know how to deal with these Moire's and filter them back out?

There is of course another reason for the user to look at his shirt - as the
AT&T commercial says: "Fred just closed the deal of his life wearing duckie
pajamas..."  ;)

                                  Valdis Kletnieks
                                  Computer Systems Engineer
                                  Virginia Polytechnic Institute