[AG-TECH] upgrade questions
renambot at cs.vu.nl
Fri Aug 2 04:18:13 CDT 2002
] -----Original Message-----
] From: Osland, CD (Chris) [mailto:C.D.Osland at rl.ac.uk]
] Sent: Friday, August 02, 2002 10:49
] To: 'Luc Renambot'; ag-tech
] Subject: RE: [AG-TECH] upgrade questions
] I take your point. We have a regular meeting (every month) with
] at least 10 sites - the current UK AG sites - all attending. This
] number is likely to increase to about 15 quite soon. The number of
] video feeds from each site varies from 1 to 4 depending on number of
] participants and I normally land up with about 5 or 6 Mediums and 15
] or so Smalls on the wall. I've noticed that this brings me up
] to 100% utilization (peaky) on our 1.4 GHz system and would like to
] have some headroom in the performance. I guess I should have stated
] my target as 60-70% utilization rather than 30 windows!
] However, as noted in an e-mail a week or so ago, I'm also interested
] in the usability of more pixels on the wall, since with even 2
] or 3 participating sites in a shared visualization project we
] rapidly run out of wall space. This would make it feasible to
] accommodate higher numbers of video feeds worthwhile. Even an
] agenda and a working doucument (say one DPPT and one VNC) puts a
] strain on wall space if there are lots of sites.
] Re higher quality feeds, we are also interested in that, but
] compressed D1 requires 270 Mbits/sec so a little compression may
] be necessary until gigabit backbones get replaced by terabit ones!
Computing like that, you get a CIF video stream in YUV color at
36.5 Mbit/sec. If you multiply by 30, you have a big network !
A DVD in MPEG-2 is around 5 Mbits/sec. Fast PC nowadays can compress
in real-time into Divx or Mpeg-4. I think there's options here...
(I use my old PC at home to compress TV in real-time in Divx, and it's
of a decent quality).
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