x11vnc and vncviewer for classroom

[Anna]

>From the original email by Arjun Sarwal:

"The idea is that in a classroom, teacher wants to have these
intermediate sessions where he just wants to explain to kids by doing
things on his screen - mainly go through specific pages of a pdf while
simultaneously explaining something orally. There are ~30 kids in the
classroom."

Another option to accomplish this is to stream the screen of the
Ubuntu machine as ogg and then the XOs can simply play the stream via
totem.

On my Ubuntu box, I installed Istanbul, changed my screen resolution
to 800x600, then did this to stream my entire desktop to the icecast
server on my XS 0.4 test box:

 gst-launch-0.10 oggmux name=mux ! shout2send ip=<myip> port=<port>
password=secret mount=ubuntu.ogg istximagesrc name=videosource
use-damage=false endx=800 endy=600 ! video/x-raw-rgb,framerate=5/1 !
videorate ! ffmpegcolorspace ! videoscale method=1 !
video/x-raw-yuv,width=800,height=600,framerate=5/1 ! theoraenc ! queue
! mux.

The stream looked really good on the XO - very clear and legible.  The
settings probably need tweaking, though, to scale up to ~30 users.

I haven't tried setting up icecast on Ubuntu, but it should be
possible to stream and broadcast on the same machine.  At any rate,
this doesn't require anything extra to be installed on the XOs
themselves.

Anna Schoolfield
Birmingham