[PD] I'm stuck in a corner, please help! RE: [delta~] object

cyrille henry cyrille.henry at la-kitchen.fr
Fri Mar 21 09:55:27 CET 2008


hello,
i think it's quite simple to emulate z~ with a simple delread~ / delwrite~.


cyrille

Andy Farnell a écrit :
> I have a problem, that is partly of my own making and need to air
> this on the list for advice. This isn't a rant, just a frustrating situation.
> 
> As some of you know I have been working on a textbook for Pd for some time.
> In the final stages and adding the practical exercises and the problem is this:
> 
> 
> The book is completely for vanilla Pd to keep things simple and I really don't
> want to change this.
> 
> I have three crucial exercises that use [delta~]
> 
> [delta~] does not exist in vanilla Pd
> 
> [delta~] must be recreated _EXACTLY_ as the external behaves.
> 
> It IS possible to recreate [delta~] exactly using [z~]
> 
> [z~] does not exist in vanilla
> 
> It is not, as far as I can see, possible to emulate [delta~] using
> [rzero~] or any other signal domain method, in a way that doesn't 
> confuse the hell out of the reader or provide unsatisfactory results. 
> 
> I am left with these options:
> 
> 
> 1) Drop three of the most interesting exercises from the textbook.
> 
> 2) Change my policy and make the textbook require pd-extended on account of
> only  _one_ object!
> 
> 3) Find a vanilla replacement for [delta~] that is simple. (less than three objects)
> 
> 4) Convince Miller to include [delta~] in vanilla
> 
> 5) Convince Miller to include [z~] in vanilla
> 
> 
> To the list: I'm hoping some bright spark will solve (3). Be warned, it isn't as
> simple as it seems, AFAICS. [rzero~] should provide a differentiator response in
> theory. In practice dealing with the offsets and scales ruins the whole show and
> leads to over-complex and unstable patches. Using [biquad~] is extremely confusing
> to most readers and I don't want to do this. You cannot obtain a single sample delay
> using [delwrite~] as far as I know, if you can it certainly means [samplerate~] must
> be added to all patches to make sure they run at different sr, which is mucho annoying.
> 
> To Miller: Please consider admitting [z~] or [delta~] (I actually prefer the former
> because it is more educational to see differentiator built from sample delay) 
> into the vanilla distro. This would need to be time for release quite soon. I'm sure
> it would greatly benefit Pd to do this.
> 
> Best regards 2 all,
> 
> Andy
> 
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