Hi Cullen,
Thanks for your comments. I want to mention some more issues with
the VNC.
1) VNC uses a client-pull mechanism which results in poor
performance in high RTT situations.
Our proposal uses a server-push mechanism.
2) VNC uses the same encoding for all updates.
This new system may use different encodings for updates in the
same session.
For example, if the user plays a movie, our implementation
detects that and uses Theora or MJPEG just for this movie region.
3) VNC uses a separate compressor for each connected user. This
results high CPU usage if more than one person connects.
Also due to this compressor issue, one can not use these
encodings in a multicast session (decompressor needs all the packets).
TeleTeachingTool uses Hextile encoding (which means uncompressed
data and bandwidth inefficiency) to overcome this limitation.
Our proposed system compresses each update only once. The
compressed updates are stored with metadata such as the top-left
coordinates, width and height.
Then ready-to-go updates are transmitted to participants. For
low bandwidth clients, the system skips some updates if they are
overwritten by the following updates.
-Omer Boyaci
On Nov 14, 2008, at 8:52 PM, Cullen Jennings wrote:
I like the idea of an applications share protocol that can be set
up over SIP and glad to see this submission.
Few comments
At a high level, why not just standardize something like VNC. It
seems like this would be better than inventing something new.
I also wondered about why run it over RTP vs just be it's own
protocol. It was not clear that RTP was a good match.
Some more small details ... you might want to look at how X deals
with mouse and keyboard events - particularly compression of mouse
motion.
Make sure that you have some way for the protocol to send a CTRL-
ALT-DEL to the far side without the user actually having to
simultaneously press CTRL, ALT and DEL.
You probably want your PLI to be able to specify a partial
rectangle to update.
Cullen in my individual contributor roll
_______________________________________________
Audio/Video Transport Working Group
avt at ietf.org
https://www.ietf.org/mailman/listinfo/avt
_______________________________________________
Audio/Video Transport Working Group
avt at ietf.org
https://www.ietf.org/mailman/listinfo/avt