Re: [gtk-vnc-devel] [PATCH] ZRLE Encoding support

[Anthony Liguori <anthony codemonkey ws>]

Jonh Wendell wrote:
> Em Qui, 2007-12-27 às 21:10 -0600, Anthony Liguori escreveu:
>   
> > Hi,
> >
> > Attached is a patch for gtk-vnc to enable the ZRLE encoding.  ZRLE is a 
> > compressed encoding that's documented in the RFB specification.  While 
> > not as popular as Tight, since it's the "official" compressed encoding 
> > for RFB I thought it was a good place to start.
> >     
>
> What do you mean by 'popular'? Is it better than ZRLE? Is it the best
> encoding available? If so, is there any plan to support it? Is it too
> complicated?
>   

Last time I looked, only RealVNC server/clients support ZRLE and only 
versions 4 and greater.  This means that derivatives based on the old 
code base (like Tightvnc) don't support it.

I'm not sure if that's still the case but it was a while ago.

I'm planning on adding support for the Tight encoding for the next 
release.  Tight is a little weirder as it uses multiple zlib streams and 
can send jpegs.  I'm not sure that one is really much better than the other.

> > I'd like to commit this before the next release (which I'll do before 
> > Monday) so please give it a try and let me know if it works for you.
> >     
>
> I tried it with Vinagre and it works perfectly, but i didn't see any
> performance improvement when compared to hextile. Didn't i do enough
> tests? (I tested against an UltraVNC server in a Windows XP)
>   

Your server may be limited in the quality it sends more than the 
bandwidth in your connection.  ZRLE/Tight use considerable less 
bandwidth especially for large screen updates.

Of course, if bandwidth is not a limiting factor, then it's better to 
use less compression.  RealVNC actually measures the available bandwidth 
and dynamically switches the preferred encoding accordingly.  It 
wouldn't be a bad idea to do something like that in gtk-vnc.

> PS: Look at the banner bellow: :P
>
>   

:-)

Regards,

Anthony Liguori

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>
> Cheers,
>