[FreeNX-kNX] NX screen refresh performance

[chris at ccburton.com]

Toni Asensi Esteve <asmond at orange.es> wrote on 26/05/2010 16:03:06:

> Chris wrote:
> > Obviously other's experiences help and we could do with more feedback 
. . . 
> .
> A week has passed and no one answered with its case :-(. I'll try to 
comment 
> on our own case, we have 
>    freenx-server   0.7.3
>    nx client for Windows 3.4.0-7
> 
> [...]
> 
> > What I did when I was looking at this, was to try the same tasks using 
both 
> > high quality jpeg and RGB and compare how it seemed to be on the 
screen. 
> 
> In our case:  the speed difference was not a great one, the 
> behaviour was a bit 
> faster using the lossless RGB compresion.
> 

The settings are changed depending upon the link speed you select.

I had ADSL, yours is set to modem !!

I was swinging windows around, which should be just compressed
X traffic not graphics at all.

With RGB the deferred updates were noticable, with a whole trail of
window edges all round the screen, but its not a real world test.

I can see more sluggish text entry with RGB than jpeg, even though
it shouldn't make any difference.

> > I found that I couldn't distinguish between the quality of image ( on 
a 
> > spreadsheet, which is one of our core apps, lots of thin straight 
black 
> > lines on a white background, just what the jpeg people say they aren't 
good
> > at ) 
> 
> In our case:  the presentation made a visible difference. I attach 
> screenshots 
> of the configuration (with "modem" settings and setting both rgb and 
jpeg 
> compression, jpeg at the highest quality) and obtaining a low quality 
result 
> in some places of the screenshot (like the buttons),

Yup, I see the button icons a bit blurry too, that's lossy jpeg I guess . 
. . .

> a result somewhat worse 
> than the Windows remote desktop protocol one, which would make us 
> look like if 
> we had something of worse quality. This is very important. Maybe it's a 
> setting that has to be tuned? :-?

There seems to be a difference in compression methodology between
bitmaps and text.