Protocol compression

Harco de Hilster harcoh "at"
Fri, 13 Mar 1998 11:17:29 +0000

Andy Eskilsson wrote:

> Just a thought, can't you control zlib's level of compression (1-9),
> therefore tune in how much you want it to work..

Yes, and it should be the client who decides what compressionlevel is required.

It's up to the ORL people to decide if they want compression to be
part of the VNC protocol. I just wanted to see if we could improve
on the default encodings at all.

An other optimization would be to sent only the real screen diffs to
the client.
E.g. the update region for xclock might be the entire clock area,
but 59 out of 60 times only the second marker is different.
That means the server should keep an extra frame buffer for each client,
and compute the diff between the update region of the real frame buffer
and the client's framebuffer.
Depending on the repaint behavior of the application, that could save a lot
of bandwidth at the expense of memory and computing on the server.



Harco de Hilster  CAOS/CAMM Center       Phone:  +31(0)24-3653379
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