A little help needed

[Greg Breland]

After looking at the Win32 code, it looks like the mouse pointer is sent in
raw bitmap format.  I modified the WinVNCserver to include bandwidth usage
stats and just moving the mouse around takes about 10k/sec.  If you have a
busy network, this could cause a slow down.  WinVNCserver maxed out the
bandwidth usage at 100k/sec when playing a movie, but normal use uses
25k/sec.  But what I don't like is that 10k/sec of that is mouse.  The
algorithms that VNC uses to transmit most of the screen updates are very
good, but sending the mouse cursor as raw bitmap, considering it is the most
often updated thing on the screen slows VNC down a lot.  There has to be a
better way to do mouse updates.  

I understand the problems of client side caching/layering techniques, but
what about having an option to turn the server mouse pointer off entirely
and just have a client side cursor?  I understand that the cursor gives you
a lot of feedback about the action you are taking when clicking, but it
might speed things up a lot.  Even better, there might be a hook on Win32
that lets you know when the cursor changes and you could use this to change
the client side cursor.  This would not be a layering/cache technique, as it
would use the true client cursor of the OS the client is using.


Greg


-----Original Message-----
From: James "Wez" Weatherall [mailto:jnw22 "at" cam.ac.uk]
Sent: Thursday, November 04, 1999 6:33 AM
To: vnc-list "at" uk.research.att.com
Subject: Re: A little help needed


> > Nothing... If the server were X-win, it would work fast, I think. I'm in
> > almost the same situation as you (but a 100Mb network), and I notice the
> > same thing. From what I've read on this list, the problem is not so much
> > getting the update acress the wire, but determining when something has
> > updated/changed... This seems to go much better under X-Win than under
> > MS-Win.
> >
> > Arnt
>
> OK, I can understand that the change detection issue is not so easy, but I
> wonder why it should be so difficult to get a smooth view when all I'm
doing
> is moving the mouse around. I just thought that it should be obvious to
VNC
> that the mouse pointer is moving and that this movement causes screen
> changes. All right... I must be missing something else. I am still trying
to
> understand what is happening behind-the-scenes in situations like that one
> described above (mouse moving only). I will be looking into the source
code
> soon. Maybe then things get clearer.

Which Polling options do you have checked in the Properties dialog?  If you
have Poll Full Screen enabled then disable it.  If you have Poll Foreground
or Poll Under Cursor then make sure that you have Poll Console Windows Only
also checked.

Cheers,

James "Wez" Weatherall
--
          "Xenophobes should go back to Xenophobia"
Laboratory for Communications Engineering, Cambridge - Tel : 766513
AT&T Labs Cambridge, UK                              - Tel : 343000




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