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Date: Wed, 21 May 2008 08:51:01 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] Sensible VNC encodings
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To: qemu-devel@nongnu.org

Jamie Lokier wrote:
> Anthony Liguori wrote:
>   
>> I really don't like the idea of using a lossy encoding though.
>>     
>
> Lossy encoding sounds very useful if you're on a very slow link and it
> would take 30s to display a major update even with the most brilliant
> of lossless compressions.  Having a blurry, progressively updated
> image until it's exact would sometimes be useful.
>   

VNC has a builtin notion of "lossy" encoding via SetPixelFormat.  You 
can use it to reduce the overall color depth.  Hextile et. al. are also 
paletted encodings so I doubt there are a lot of circumstances where 
jpeg compression really saves you anything.

If someone wants to actually do some experiments and can post numbers 
where jpeg compression provides the best bandwidth/quality, I'd be happy 
to implement it.  FWIW, Tight is not part of the RFB spec.  ZRLE (which 
is meant to replace it) does not support JPEG encoding at all.

Regards,

Anthony Liguori

> -- Jamie
>
>
>