[PD] HID and timestamp

[Hans-Christoph Steiner]

Yes, this is an area that needs some work, but its not an easy problem  
unfortunately.  Have you tried setting the poll time to 2ms?  That's  
about as fast as it can go.  Basically, you can't expect smooth data  
out of a device or sensor even it the values were coming out one at a  
time.  I recommend smoothing the output using averaging or low-pass  
filtering.  Try [hid_average] for example.

Going forward, it would be a good idea for [hid] to output one value  
per cycle when polling absolute axes like what the Wacom gives you.   
Its on the TODO list, but I have had little time recently to work on  
[hid] since I am working numerous freelance jobs to pay the bills.  I  
have applied for a 1 year fellowship to work on this, let's hope I get  
it.

.hc

On Aug 27, 2005, at 1:50 AM, etienne deleflie wrote:

> Hello,
>
> I'm getting stuttering data output from my wacom tablet using the  
> latest HID.
>
> stuttering .... I put a [timer] on the output of the abs X position  
> messages, and discovered that the HID object spits out around 4 X  
> position messages in one go ..... i.e. without any time delay.
>
> I've got a patch where you can really hear this (it is using a vd~ to  
> do a dopler effect on ambisonic spatialisation stuff).... if I do a  
> straight consistent line on my Wacom, the output comes out all  
> stuttery and spitty.... and I have traced the reason to the fact that  
> (around) 4 messages get spat out at once. NOTE: changeing the poll  
> value of the HID object does not aleviate the problem.
>
> I concluded that this is what the timestamp (inlcuded in the USB  
> messages) is for.... right? .......... the USB driver _or_ the USB  
> device( I dont know about these things) instantaneously spits out 4 X  
> positions and includes the timestamp between them.... so it should be  
> (by using those timestamps) possible to get PureData to space out  
> those 4 messages in time and hence get a smooth data line.
>
> do I sound like I dont know what I am talking about? does anyone want  
> to educate me?
>
> Etienne
>
>
>
>
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