Re: [Linuxwacom-discuss] Intuos4 and pointer jitter

[SHIRAKAWA A. <shi...@gm...>]

Emil Assarsson wrote:
> I don't know that much about the windows driver but they maybe uses
> some kind of reduction of the jitter for the pointer. it might be an
> idea to add some kind of "sluggishness" that average the last 10 ms
> position data to the xorg driver for the pointer.

Well, in Linux drivers there's already a "RawSample" setting which 
averages the last N pointer position samples. Most Wacom tablets have a 
133 Hz sample rate, so a RawSample of 4 samples (the default value) 
already averages about 30 milliseconds of data (1000/133*4). Ramping up 
this setting doesn't bring appreciable changes on jitter unless high 
values are used (15 and up), which introduce in my opinion excessive 
pointer lag.

Windows drivers work perfectly with no lag, so if they have some jitter 
reduction feature, it's probably not just by averaging the last few data 
samples.

By the way, if on Linux Wacom drivers we had an option to use on Intuos4 
tablets the special 200 Hz sampling rate mode, a higher "RawSample" 
setting could be used without adding more pointer lag (for a target of 
30 ms, we could use a RawSample value of 6 with no difference compared 
to the 133 Hz mode). To the developers reading this: are there any plans 
to introduce this option in the near future? It's rather useful (not 
only to raise RawSample, of course).

-- 
SHIRAKAWA Akira