Re: [Qemu-devel] Re: [PATCH 7/7] Add tight encoding (jpeg) to vnc.c

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Anthony Liguori wrote:

> If we implement Tight and then use jpeg by default, for most clients,
> the default is going to be lossy encoding.  While lossy isn't so bad for
> high detailed images (like pictures), it's pretty terrible for simple,
> high contrast images (like windows in a desktop).
> 
> TightVNC has some sophisticated heuristics for determining whether to
> use jpeg or not (when it's enabled).  I think that sort of heuristic is
> a prerequisite for enabling tight's jpeg support.
> 
> FWIW, Tight essentially does hextile encoding but adds zlib
> compression.  That's probably a better place to start as it should
> outperform hextile while remaining lossless.
> 

Another thing to consider is that using jpeg compression is going to
worsen qemu performances, so I think it should be used only when
necessary, e.g. the network connection between client and server is  bad.