Re: Boxy video

Tim_Dorcey@cornell.edu
Tue, 25 Apr 1995 10:32:12 -0400


At 1:35 PM 4/24/95 -0700, Michael Sattler wrote:
>At 4:02 PM 4/23/95, Andrew Barilla wrote:
>>When I use CUSeeme I get only part of each window. Just a bunch of boxes of
>>video. Is this right or is something set up wrong.
>
>This is right. CU-SeeMe only updates each portion of the screen as it's
>changed (by, for example, a moving object). There's no way, currently, to
>say "yo! send me the whole image and start me from here".

True, although non-changing squares are also updated if they get too "old"
(i.e., have not been transmitted for x frames). Otherwise, a lost packet
could corrupt the picture indefinitely. The number "x" is set by the
"Refresh Interval" control under "Compression" settings. Also, each sender
is aware of when a new receiver opens their window, and the square "ages"
are adjusted to speed up the fill-in beyond what is provided by the Refresh
Interval (obviously, we could just send the entire frame at that time, but
such a burst would increase the likelihood of packet loss on a loaded
link). Persistent blockiness is a result of high packet-loss. Reducing
the number of windows you are watching should help (assuming that you would
prefer 1 clear picture to lots of blotchy ones).

Tim
__________________________________________________________________
Tim Dorcey Tim_Dorcey@cornell.edu
Sr. Programmer/Analyst (607) 255-5715
Advanced Technologies & Planning
CIT Network Resources
Cornell University
Ithaca, NY 14850
__________________________________________________________________