Re: set_encoding() in VncDisplay

[Jonh Wendell <jwendell gnome org>]

Hi, Daniel.

Em Ter, 2009-09-01 às 15:52 +0100, Daniel P. Berrange escreveu:
> On Mon, Aug 31, 2009 at 05:19:05PM -0300, Jonh Wendell wrote:
> > Hi, folks.
> > 
> > I've created this function in 'encoding' branch of gtk-vnc[1]
> 
> I'd prefer it if patches are sent to the list, rather than pushed to
> branches in the repo - it is not good practice to publish throw-away
> branches in the main repository. Once something is pushed to the main
> repo it should never be deleted or rebased, because that can cause
> trouble / confusion for people tracking the repo.

Ok, will do that next times.

> I'm not really understanding the point of this new function, adding
> two tunables
> 
>   VNC_DISPLAY_ENCODING_SPEED
>   VNC_DISPLAY_ENCODING_QUALITY
> 
> When 'SPEED' is set, it is just adding the ZRLE encoding, and swapping
> order of RRE/COPYRECT, and then duplicating the existing tunable for
> allowing JPEG or not. ZRLE, RRE, COPYRIGHT are all loss-less encodings
> so if one order is faster, it should be used all the time, there is no
> quality issue involved in that choice. 

My idea is: slow (low power cpu) machines accessing servers in local
network could use the 'QUALITY' flag, thus avoiding zlib operations. 

Also, my idea is to implement the 'AUTO' flag, just like vncviewer does,
based on network throughput. Most of times applications will want to use
AUTO flag, but 'advanced' users might want to tune that setting.

> If that ordering is determined, then having a set_encoding method is 
> redundant since we already have a set_lossy method for turning on/off
> JPEG encodings which do impact quality.

I think that even choosing 'SPEED' setting we should not use tight jpeg
by default. So, this function should be used, just like it's used
currently.

Once this get accepted, I'll add an 'connection options' dialog in
vinagre, allowing the user to change those flags.

> BTW, on the performance front we could do with having a method to set
> an artificially lower colour depth. Switching from 32/24-bit to 16-bit
> colour depth can hugely increase our performance

Yes, that will be my next job ;)

> Regards,
> Daniel

Cheers,
-- 
Jonh Wendell
http://www.bani.com.br