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

cyrille henry cyrille.henry at la-kitchen.fr
Fri Mar 21 11:41:26 CET 2008



Andy Farnell a écrit :
> Doesn't quite work. If you try it with 1/sr in place of [z~] in a patch that's
> sensitive to it the results are wrong . Not sure why.
> 
this is strange.
look at my exemple, it show that it should work. (1 signal is delayed with z~ and with delread/write; diference of both is pure silence)

Could you send the patch you tested?

cyrille


> andy
> 
> On Fri, 21 Mar 2008 09:55:27 +0100
> cyrille henry <cyrille.henry at la-kitchen.fr> wrote:
> 
>> 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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