[PD] smoothing things ...

B. Bogart ben at ekran.org
Tue Jul 26 16:17:07 CEST 2005


Hey Thoralf,

The way I see it is that what you want is a circular interpolator. That is
one that knows 0 and 359 are one step away not 359 steps away. I think
this would be useful for a number of things where wrapping (roll-over) is
desired, of course your example of rotation is a good representation.

I have not looked at Frank's patch yet, maybe it is such a thing?

To roll-over at a certain point would be done by multiplying the scale 0-1
(where 0 & 1 are the same point) by your scale (360). I'm not sure what
you mean by a smoother that would deal with data in whatever shape... you
would always need to tell it the roll-over point.

lop~ method will deal with any incoming value and interpolate from the
last position to the target. without roll-over this does satisfy your
first need.  I guess it would be a matter of a "roll-over" mode. Of course
the roll-over interpolator would not interpolate at all if you sent it 0
and then 1. Which is most cases would be desired.

that is enough of me.

b>


> Hi Johannes, hi list,
>
>> i don't think that you can use soemthing like "set
>> <f>" with dsp-filters.
> bad news ...
>
>> now that'll be cool: doing interpolation between
>> (however yet) unknown
>> values.
>> i guess this would solve many many problems.
> Yeah. Perfect knowledge of the future is a good thing.
> Let's throw probability on the garbage dump ...
> Seriously, the mail I wrote yesterday didn't make much
> sense, it was a hot day here :-).
> I'll try to reformulate my problem: I need a filter
> that interpolates control signals in real time.
> Ideally, this filter would be self-adopting in a way
> that it could be fed with control data that are a)
> non-predictable and b) come in in varying intervals
> and that it (the filter) would still output smooth
> curves. Another prerequisite is that the filter is
> able to recognise parameter jumps that exceed a
> certain threshold and doesn't interpolate these jumps.
> I realise that this is probably impossible to
> accomplish.
>
>> a simple non-linear (IIR) low-pass filter is
>> x[n]=a*x[n-1]+(1-a)*y[n]
>> (with 0<=a<=1)
> So this would basically be lop~ , but not in the
> frequency domain? I'm a bit confused about the y[n],
> shouldn't that be x[n] as well?
> Sorry, I'm totally new to this ...
>
> thank you,
> thoralf (quite confused).
>
>
>
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