[PD] Sigmund+reblocking

[Fede Camara Halac]

Hi all,

Would reblocking a subpatch have any effect on [sigmund~]? 

Below is what I did. My idea was to delay the signal by one sample before going 
to sigmund. This is certainly not what is happening, though, but sigmund still 
works for all 10 tracks as if no reblocking had been made. Is sigmund 
overriding the block object and reblocking to 128?

[block~ 1]

[inlet~]
|
[sigmund~ -hop 1024 -npeak 10 tracks]
|
[outlet~]


Thanks!

Fede

fedecamarahalac.com



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Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?

[Ed Kelly via Pd-list]

PS - I normally use cyclone/svf~ in my objects, but there is a good argument 
for a decent state-variable filter included in vanilla I think.Ed
 


On Sunday, 16 October 2016, 4:52, Ed Kelly  wrote:
 
 

 Hey people,
While I'm not an expert with digital filters, I did manage to piece together a 
decent-sounding ladder emulation instead of vcf~ a while ago. It only does 
resonant lowpass though. It's called mvcf~ and is found in the ekext externals 
library.
I've since been reading about analogue filter design and I reckon there may be 
high pass and band pass filters available from the source code, with the 
correct adjustment to the algorithm. I'm trying to work out how to adjust the 
coefficients to accurately model the alternative functions (i.e. highpass, and 
hence bandpass through arithmetic processes) according to the resistance 
factors outlined in this paper. Any help would be appreciated :)
So, currently, at line 78 in the code I have translations for highpass and 
bandpass (the current implementation is lowpass only with a gain factor) but I 
may be stupid in not trying this myself (or I've just been super-busy with 
other stuff!). The idea of implementing the other two modes comes from an 
Electronotes paper from Bernie Hutchins in the 1970s. This doesn't seem to be 
free online any more, but I've enclosed it.
Take a look.Cheers,Ed



Lone Shark releases: Light Vessel Automatic available now on 12" vinyl.Build 
Your Wings on the Way Down, the new digital album available @ 
http://scifirecords.co.uk/releases 
Earthlings compilation is out now @ http://www.pyramidtransmissions.com

Ninja Jamm - the revolutionary music remix app for iOS and Android: 
http://www.ninjajamm.com/

Gemnotes-0.2: Live music notation for Pure Data, and Metastudio 5 live 
composition and improvisation suite, available at 
http://sharktracks.co.uk/html/software.html 

   

 On Saturday, 15 October 2016, 22:10, Julian Brooks  wrote:
 
 

 And my learning for the day is done.

Thanks both

On 15 October 2016 at 15:59, katja  wrote:

Thanks for your pointers Christof. The recipe you mention from
arpchord.com is different than iemlib's, but yields identical
normalization and feedback coefficients, thus the same beautiful
response. As you say, what's in the textbooks is common knowledge and
can be used by everyone. Now I'll try to get the same result in C.

By the way, [iemlib/hp~] seems to recalculate coefficients for every
dsp vector which explains the higher CPU load.

Katja

On Sat, Oct 15, 2016 at 1:59 PM, Christof Ressi  wrote:
>> If iemlib's license allows to use the recipe in BSD
>
> IMHO, the correct formular for the cutoff frequency below (which I guess is 
> also used in [hp1~] since the frequency response is the same) is 'common 
> knowledge', so I don't think you'd have to pay attention to any licence.
>
>
>> Gesendet: Samstag, 15. Oktober 2016 um 13:52 Uhr
>> Von: "Christof Ressi" 
>> An: katja , "Miller Puckette" 
>> Cc: pd-list 
>> Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?
>>
>> > But coefficients aren't recalculated so
>> > often, therefore this difference will be negligible.
>>
>> That's a good point. You're right that both involve a feedback and 
>> feedforward, so I'm wondering why [hp1~] needs more CPU... otherwise, 
>> iemlib's filters are very efficient.
>>
>> Anyway, I researched a bit and found the reason why the frequency response 
>> of Pd filters seems 'wrong':
>>
>> Miller uses a formular for calculating the cutoff frequency which is taken 
>> from analog filters but is not really adequate for digital filters since it 
>> doesn't reflect the cyclic nature of the digital domain (although you can 
>> see it in some articles on digital filters).
>>
>> Let's take [hip~] as an example:
>>
>> the formular for a 1-pole 1-zero highpass goes:
>> y[n] = (x[n] - x[n-1]) * (1 + k) / 2   +   k * y[n-1]
>>
>> Miller calculates the position of the pole with
>> k = 1 - (fc * 2*pi / SR).
>>
>> The correct formular, however (if you want the frequency response to be zero 
>> at Nyquist!), would be
>> k = (1-sin(a))/cos(a), where a = fc * 2*pi / SR.
>>
>> You can find it here: http://www.arpchord.com/pdf/ 
>> coeffs_first_order_filters_ 0p1.pdf
>>
>> BTW, the reason why [hip~] seems to get stuck at 7018 Hz is because Miller 
>> clips the coefficient below 0, so it never reaches -1 (where the gain would 
>> be all zero).
>>
>> Also, there is another approximation with a similiar behaviour, which goes 
>> like this:
>> k = e^(-2*pi*fc/SR). I could find it here: http://www.dspguide.com/ch19/ 
>> 2.htm
>> Here, the pole can only move from 1 to 0 and doesn't ever reach -1 as well.
>>
>> Now, is the behaviour of [hip~] 'wrong'?
>> If you define at 1-pole 1-zero high pass filter as something which passes 
>> everything at fc = DC 

Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?

[Julian Brooks]

And my learning for the day is done.

Thanks both

On 15 October 2016 at 15:59, katja  wrote:

> Thanks for your pointers Christof. The recipe you mention from
> arpchord.com is different than iemlib's, but yields identical
> normalization and feedback coefficients, thus the same beautiful
> response. As you say, what's in the textbooks is common knowledge and
> can be used by everyone. Now I'll try to get the same result in C.
>
> By the way, [iemlib/hp~] seems to recalculate coefficients for every
> dsp vector which explains the higher CPU load.
>
> Katja
>
> On Sat, Oct 15, 2016 at 1:59 PM, Christof Ressi 
> wrote:
> >> If iemlib's license allows to use the recipe in BSD
> >
> > IMHO, the correct formular for the cutoff frequency below (which I guess
> is also used in [hp1~] since the frequency response is the same) is 'common
> knowledge', so I don't think you'd have to pay attention to any licence.
> >
> >
> >> Gesendet: Samstag, 15. Oktober 2016 um 13:52 Uhr
> >> Von: "Christof Ressi" 
> >> An: katja , "Miller Puckette" 
> >> Cc: pd-list 
> >> Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?
> >>
> >> > But coefficients aren't recalculated so
> >> > often, therefore this difference will be negligible.
> >>
> >> That's a good point. You're right that both involve a feedback and
> feedforward, so I'm wondering why [hp1~] needs more CPU... otherwise,
> iemlib's filters are very efficient.
> >>
> >> Anyway, I researched a bit and found the reason why the frequency
> response of Pd filters seems 'wrong':
> >>
> >> Miller uses a formular for calculating the cutoff frequency which is
> taken from analog filters but is not really adequate for digital filters
> since it doesn't reflect the cyclic nature of the digital domain (although
> you can see it in some articles on digital filters).
> >>
> >> Let's take [hip~] as an example:
> >>
> >> the formular for a 1-pole 1-zero highpass goes:
> >> y[n] = (x[n] - x[n-1]) * (1 + k) / 2   +   k * y[n-1]
> >>
> >> Miller calculates the position of the pole with
> >> k = 1 - (fc * 2*pi / SR).
> >>
> >> The correct formular, however (if you want the frequency response to be
> zero at Nyquist!), would be
> >> k = (1-sin(a))/cos(a), where a = fc * 2*pi / SR.
> >>
> >> You can find it here: http://www.arpchord.com/pdf/
> coeffs_first_order_filters_0p1.pdf
> >>
> >> BTW, the reason why [hip~] seems to get stuck at 7018 Hz is because
> Miller clips the coefficient below 0, so it never reaches -1 (where the
> gain would be all zero).
> >>
> >> Also, there is another approximation with a similiar behaviour, which
> goes like this:
> >> k = e^(-2*pi*fc/SR). I could find it here:
> http://www.dspguide.com/ch19/2.htm
> >> Here, the pole can only move from 1 to 0 and doesn't ever reach -1 as
> well.
> >>
> >> Now, is the behaviour of [hip~] 'wrong'?
> >> If you define at 1-pole 1-zero high pass filter as something which
> passes everything at fc = DC and blocks everything at fc = Nyquist, then
> I'd say yes.
> >> If it should roughly model an analogue filter (where the cutoff
> frequency can go up to infinity) for low cutoff frequencies only, then I'd
> say no.
> >>
> >> Also, as I tried to point out, this issue with the cutoff frequency is
> true for all Pd filters!
> >>
> >> So I think this behaviour should either be changed (great, if Katja is
> willing to submit a patch!) or documented in the help patch (gain is not 0
> at Nyquist!).
> >>
> >> I'm not an engineer or any expert on filter design. It's just my two
> cents :-)
> >>
> >> Christof
> >>
> >>
> >>
> >>
> >>
> >> > Gesendet: Samstag, 15. Oktober 2016 um 11:39 Uhr
> >> > Von: katja 
> >> > An: "Christof Ressi" 
> >> > Cc: pd-list 
> >> > Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?
> >> >
> >> > I'm pretty confident [hip~] would not loose its efficiency when using
> >> > iemlib's recipe. Both hi pass filters have a feed forward and feedback
> >> > component, with coefficients for normalization and feedback.
> >> > Calculation of these coefficients is a bit more involved with iemlib's
> >> > recipe, using trig functions. But coefficients aren't recalculated so
> >> > often, therefore this difference will be negligible.
> >> >
> >> > To reassure, it is not my intention to spark another 'what's wrong
> >> > with pd' thread. If iemlib's license allows to use the recipe in BSD
> >> > code I'll try patch the C of [hip~] and submit on the tracker for
> >> > review. Who knows, it may be a no-brainer.
> >> >
> >> > Katja
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > On Sat, Oct 15, 2016 at 2:34 AM, Christof Ressi <
> christof.re...@gmx.at> wrote:
> >> > > There are a number of big problems with all build-in filters in Pd
> (expect for the raw filters).
> >> > >
> >> > > Problem number 1:
> >> > > [lop~] 

Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?

[katja]

Thanks for your pointers Christof. The recipe you mention from
arpchord.com is different than iemlib's, but yields identical
normalization and feedback coefficients, thus the same beautiful
response. As you say, what's in the textbooks is common knowledge and
can be used by everyone. Now I'll try to get the same result in C.

By the way, [iemlib/hp~] seems to recalculate coefficients for every
dsp vector which explains the higher CPU load.

Katja

On Sat, Oct 15, 2016 at 1:59 PM, Christof Ressi  wrote:
>> If iemlib's license allows to use the recipe in BSD
>
> IMHO, the correct formular for the cutoff frequency below (which I guess is 
> also used in [hp1~] since the frequency response is the same) is 'common 
> knowledge', so I don't think you'd have to pay attention to any licence.
>
>
>> Gesendet: Samstag, 15. Oktober 2016 um 13:52 Uhr
>> Von: "Christof Ressi" 
>> An: katja , "Miller Puckette" 
>> Cc: pd-list 
>> Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?
>>
>> > But coefficients aren't recalculated so
>> > often, therefore this difference will be negligible.
>>
>> That's a good point. You're right that both involve a feedback and 
>> feedforward, so I'm wondering why [hp1~] needs more CPU... otherwise, 
>> iemlib's filters are very efficient.
>>
>> Anyway, I researched a bit and found the reason why the frequency response 
>> of Pd filters seems 'wrong':
>>
>> Miller uses a formular for calculating the cutoff frequency which is taken 
>> from analog filters but is not really adequate for digital filters since it 
>> doesn't reflect the cyclic nature of the digital domain (although you can 
>> see it in some articles on digital filters).
>>
>> Let's take [hip~] as an example:
>>
>> the formular for a 1-pole 1-zero highpass goes:
>> y[n] = (x[n] - x[n-1]) * (1 + k) / 2   +   k * y[n-1]
>>
>> Miller calculates the position of the pole with
>> k = 1 - (fc * 2*pi / SR).
>>
>> The correct formular, however (if you want the frequency response to be zero 
>> at Nyquist!), would be
>> k = (1-sin(a))/cos(a), where a = fc * 2*pi / SR.
>>
>> You can find it here: 
>> http://www.arpchord.com/pdf/coeffs_first_order_filters_0p1.pdf
>>
>> BTW, the reason why [hip~] seems to get stuck at 7018 Hz is because Miller 
>> clips the coefficient below 0, so it never reaches -1 (where the gain would 
>> be all zero).
>>
>> Also, there is another approximation with a similiar behaviour, which goes 
>> like this:
>> k = e^(-2*pi*fc/SR). I could find it here: http://www.dspguide.com/ch19/2.htm
>> Here, the pole can only move from 1 to 0 and doesn't ever reach -1 as well.
>>
>> Now, is the behaviour of [hip~] 'wrong'?
>> If you define at 1-pole 1-zero high pass filter as something which passes 
>> everything at fc = DC and blocks everything at fc = Nyquist, then I'd say 
>> yes.
>> If it should roughly model an analogue filter (where the cutoff frequency 
>> can go up to infinity) for low cutoff frequencies only, then I'd say no.
>>
>> Also, as I tried to point out, this issue with the cutoff frequency is true 
>> for all Pd filters!
>>
>> So I think this behaviour should either be changed (great, if Katja is 
>> willing to submit a patch!) or documented in the help patch (gain is not 0 
>> at Nyquist!).
>>
>> I'm not an engineer or any expert on filter design. It's just my two cents 
>> :-)
>>
>> Christof
>>
>>
>>
>>
>>
>> > Gesendet: Samstag, 15. Oktober 2016 um 11:39 Uhr
>> > Von: katja 
>> > An: "Christof Ressi" 
>> > Cc: pd-list 
>> > Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?
>> >
>> > I'm pretty confident [hip~] would not loose its efficiency when using
>> > iemlib's recipe. Both hi pass filters have a feed forward and feedback
>> > component, with coefficients for normalization and feedback.
>> > Calculation of these coefficients is a bit more involved with iemlib's
>> > recipe, using trig functions. But coefficients aren't recalculated so
>> > often, therefore this difference will be negligible.
>> >
>> > To reassure, it is not my intention to spark another 'what's wrong
>> > with pd' thread. If iemlib's license allows to use the recipe in BSD
>> > code I'll try patch the C of [hip~] and submit on the tracker for
>> > review. Who knows, it may be a no-brainer.
>> >
>> > Katja
>> >
>> >
>> >
>> >
>> >
>> > On Sat, Oct 15, 2016 at 2:34 AM, Christof Ressi  
>> > wrote:
>> > > There are a number of big problems with all build-in filters in Pd 
>> > > (expect for the raw filters).
>> > >
>> > > Problem number 1:
>> > > [lop~] and [hip~] both use a weird (you could also say: wrong) formula 
>> > > for the cutoff frequency which makes them gradually converge to a fixed 
>> > > output state (reached by about 7000 Hz). The same is true for [vcf~] and 
>> > > [bp~] with Q <= 1. Therefore the 

Re: [PD] on android to root n linux or not

[Billy Stiltner]

its kinda crazy, am at the studio and found an old notebook with a beat
matrix pattern drawn out for one of my drum loops like 20 years ago. i
think the program that was used was called awave, it was a simple program,
no midi just painting with waves on a grid. to change the pitch of an
event, the mouse was dragged up or down or a keypress on selected event
would also work. seems like i used cool edit pro and cakewalk at first for
live audio recording in realtime and the latency 20 years ago didnt seem as
bad as it has been in the last 10 years at times.  i guess its called
operating system bloat.
I might have developed a solution to the message handling waste of cpu for
unneeded message checking all those years ago.
so neat to find an old notebook, it kinda brings back the memories of what
i need to program. its like i had a great idea and maybe i can use that
idea to make things work the way they ought to instead of the way they work
for the sake of every reason besides why i need things to work, lol.
anyways, thanks for the info patrice, @Dan. yes 1 GHz is better than 66MHz,
these things ought to be smokin as  dsp.
  and as far as dns server, seems like freeBSD server had http server as
well as dns server  way back then. am needing to set up a server like right
now anyways so will let you know what i find,
here is for your sidetrack reading pleasure
http://bdm.cc/2014/02/adat-layla/

On Sat, Oct 15, 2016 at 12:39 AM, Dan Wilcox  wrote:

> Maybe android is best used to send OSC messages to a pd patch running on a
> real computer.
> You have the accelerometers and possibly other sensors builtin, the whole
> thing is a gesture controller not a dsp machine.
>
> Martin
>
>
> Tell that to RjDj. dsp on mobile has been a reality for some time now and
> getting more capable every year. How long ago was it we were all doing live
> patches on single core ~1 Ghz machines? :)
>
> 
> Dan Wilcox
> @danomatika 
> danomatika.com
> robotcowboy.com
>
>
> ___
> Pd-list@lists.iem.at mailing list
> UNSUBSCRIBE and account-management -> https://lists.puredata.info/
> listinfo/pd-list
>
>
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Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?

[Ivica Ico Bukvic]

Jumping in on this thread:

If anyone who can tackle improvements on these filters can provide a 
patch for lop~, hip~, bp~ and vcf~, please copy me when submitting the 
patch, so that I can merge it with pd-l2ork. Thank you.


Best,

Ico


On 10/15/2016 7:59 AM, Christof Ressi wrote:

If iemlib's license allows to use the recipe in BSD

IMHO, the correct formular for the cutoff frequency below (which I guess is 
also used in [hp1~] since the frequency response is the same) is 'common 
knowledge', so I don't think you'd have to pay attention to any licence.



Gesendet: Samstag, 15. Oktober 2016 um 13:52 Uhr
Von: "Christof Ressi" 
An: katja , "Miller Puckette" 
Cc: pd-list 
Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?


But coefficients aren't recalculated so
often, therefore this difference will be negligible.

That's a good point. You're right that both involve a feedback and feedforward, 
so I'm wondering why [hp1~] needs more CPU... otherwise, iemlib's filters are 
very efficient.

Anyway, I researched a bit and found the reason why the frequency response of 
Pd filters seems 'wrong':

Miller uses a formular for calculating the cutoff frequency which is taken from 
analog filters but is not really adequate for digital filters since it doesn't 
reflect the cyclic nature of the digital domain (although you can see it in 
some articles on digital filters).

Let's take [hip~] as an example:

the formular for a 1-pole 1-zero highpass goes:
y[n] = (x[n] - x[n-1]) * (1 + k) / 2   +   k * y[n-1]

Miller calculates the position of the pole with
k = 1 - (fc * 2*pi / SR).

The correct formular, however (if you want the frequency response to be zero at 
Nyquist!), would be
k = (1-sin(a))/cos(a), where a = fc * 2*pi / SR.

You can find it here: 
http://www.arpchord.com/pdf/coeffs_first_order_filters_0p1.pdf

BTW, the reason why [hip~] seems to get stuck at 7018 Hz is because Miller 
clips the coefficient below 0, so it never reaches -1 (where the gain would be 
all zero).

Also, there is another approximation with a similiar behaviour, which goes like 
this:
k = e^(-2*pi*fc/SR). I could find it here: http://www.dspguide.com/ch19/2.htm
Here, the pole can only move from 1 to 0 and doesn't ever reach -1 as well.

Now, is the behaviour of [hip~] 'wrong'?
If you define at 1-pole 1-zero high pass filter as something which passes 
everything at fc = DC and blocks everything at fc = Nyquist, then I'd say yes.
If it should roughly model an analogue filter (where the cutoff frequency can 
go up to infinity) for low cutoff frequencies only, then I'd say no.

Also, as I tried to point out, this issue with the cutoff frequency is true for 
all Pd filters!

So I think this behaviour should either be changed (great, if Katja is willing 
to submit a patch!) or documented in the help patch (gain is not 0 at Nyquist!).

I'm not an engineer or any expert on filter design. It's just my two cents :-)

Christof






Gesendet: Samstag, 15. Oktober 2016 um 11:39 Uhr
Von: katja 
An: "Christof Ressi" 
Cc: pd-list 
Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?

I'm pretty confident [hip~] would not loose its efficiency when using
iemlib's recipe. Both hi pass filters have a feed forward and feedback
component, with coefficients for normalization and feedback.
Calculation of these coefficients is a bit more involved with iemlib's
recipe, using trig functions. But coefficients aren't recalculated so
often, therefore this difference will be negligible.

To reassure, it is not my intention to spark another 'what's wrong
with pd' thread. If iemlib's license allows to use the recipe in BSD
code I'll try patch the C of [hip~] and submit on the tracker for
review. Who knows, it may be a no-brainer.

Katja





On Sat, Oct 15, 2016 at 2:34 AM, Christof Ressi  wrote:

There are a number of big problems with all build-in filters in Pd (expect for 
the raw filters).

Problem number 1:
[lop~] and [hip~] both use a weird (you could also say: wrong) formula for the 
cutoff frequency which makes them gradually converge to a fixed output state 
(reached by about 7000 Hz). The same is true for [vcf~] and [bp~] with Q <= 1. 
Therefore the actual cutoff frequency is only correct for very low frequencies and 
approximately gets more and more off until it doesn't move at all.

Problem number 2:
[bp~] and [vcf~] don't have zeros at DC and Nyquist. For low Q values, the 
slope is different for each side and changes with frequency.

Problem number 3:
the gain at the center frequency is not 1 for both [bp~] and [vcf~]. It rather 
depends on frequency and Q. [bp~] even has has a gain of 2 for Q <= 1!

I did some FFT plots, see the attachment.

I remember Miller saying somewhere that these filters are not designed for high 
cutoff frequencies - but even for 

Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?

[Christof Ressi]

> If iemlib's license allows to use the recipe in BSD

IMHO, the correct formular for the cutoff frequency below (which I guess is 
also used in [hp1~] since the frequency response is the same) is 'common 
knowledge', so I don't think you'd have to pay attention to any licence.


> Gesendet: Samstag, 15. Oktober 2016 um 13:52 Uhr
> Von: "Christof Ressi" 
> An: katja , "Miller Puckette" 
> Cc: pd-list 
> Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?
>
> > But coefficients aren't recalculated so
> > often, therefore this difference will be negligible.
> 
> That's a good point. You're right that both involve a feedback and 
> feedforward, so I'm wondering why [hp1~] needs more CPU... otherwise, 
> iemlib's filters are very efficient.
> 
> Anyway, I researched a bit and found the reason why the frequency response of 
> Pd filters seems 'wrong':
> 
> Miller uses a formular for calculating the cutoff frequency which is taken 
> from analog filters but is not really adequate for digital filters since it 
> doesn't reflect the cyclic nature of the digital domain (although you can see 
> it in some articles on digital filters).
> 
> Let's take [hip~] as an example: 
> 
> the formular for a 1-pole 1-zero highpass goes:
> y[n] = (x[n] - x[n-1]) * (1 + k) / 2   +   k * y[n-1]
> 
> Miller calculates the position of the pole with 
> k = 1 - (fc * 2*pi / SR).
> 
> The correct formular, however (if you want the frequency response to be zero 
> at Nyquist!), would be 
> k = (1-sin(a))/cos(a), where a = fc * 2*pi / SR. 
> 
> You can find it here: 
> http://www.arpchord.com/pdf/coeffs_first_order_filters_0p1.pdf
> 
> BTW, the reason why [hip~] seems to get stuck at 7018 Hz is because Miller 
> clips the coefficient below 0, so it never reaches -1 (where the gain would 
> be all zero).
> 
> Also, there is another approximation with a similiar behaviour, which goes 
> like this: 
> k = e^(-2*pi*fc/SR). I could find it here: http://www.dspguide.com/ch19/2.htm
> Here, the pole can only move from 1 to 0 and doesn't ever reach -1 as well.
> 
> Now, is the behaviour of [hip~] 'wrong'?
> If you define at 1-pole 1-zero high pass filter as something which passes 
> everything at fc = DC and blocks everything at fc = Nyquist, then I'd say 
> yes. 
> If it should roughly model an analogue filter (where the cutoff frequency can 
> go up to infinity) for low cutoff frequencies only, then I'd say no.
> 
> Also, as I tried to point out, this issue with the cutoff frequency is true 
> for all Pd filters!
> 
> So I think this behaviour should either be changed (great, if Katja is 
> willing to submit a patch!) or documented in the help patch (gain is not 0 at 
> Nyquist!).
> 
> I'm not an engineer or any expert on filter design. It's just my two cents :-)
> 
> Christof
> 
> 
> 
> 
> 
> > Gesendet: Samstag, 15. Oktober 2016 um 11:39 Uhr
> > Von: katja 
> > An: "Christof Ressi" 
> > Cc: pd-list 
> > Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?
> >
> > I'm pretty confident [hip~] would not loose its efficiency when using
> > iemlib's recipe. Both hi pass filters have a feed forward and feedback
> > component, with coefficients for normalization and feedback.
> > Calculation of these coefficients is a bit more involved with iemlib's
> > recipe, using trig functions. But coefficients aren't recalculated so
> > often, therefore this difference will be negligible.
> > 
> > To reassure, it is not my intention to spark another 'what's wrong
> > with pd' thread. If iemlib's license allows to use the recipe in BSD
> > code I'll try patch the C of [hip~] and submit on the tracker for
> > review. Who knows, it may be a no-brainer.
> > 
> > Katja
> > 
> > 
> > 
> > 
> > 
> > On Sat, Oct 15, 2016 at 2:34 AM, Christof Ressi  
> > wrote:
> > > There are a number of big problems with all build-in filters in Pd 
> > > (expect for the raw filters).
> > >
> > > Problem number 1:
> > > [lop~] and [hip~] both use a weird (you could also say: wrong) formula 
> > > for the cutoff frequency which makes them gradually converge to a fixed 
> > > output state (reached by about 7000 Hz). The same is true for [vcf~] and 
> > > [bp~] with Q <= 1. Therefore the actual cutoff frequency is only correct 
> > > for very low frequencies and approximately gets more and more off until 
> > > it doesn't move at all.
> > >
> > > Problem number 2:
> > > [bp~] and [vcf~] don't have zeros at DC and Nyquist. For low Q values, 
> > > the slope is different for each side and changes with frequency.
> > >
> > > Problem number 3:
> > > the gain at the center frequency is not 1 for both [bp~] and [vcf~]. It 
> > > rather depends on frequency and Q. [bp~] even has has a gain of 2 for Q 
> > > <= 1!
> > >
> > > I did some FFT plots, see the attachment.
> > >
> > > I remember Miller 

Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?

[Christof Ressi]

> But coefficients aren't recalculated so
> often, therefore this difference will be negligible.

That's a good point. You're right that both involve a feedback and feedforward, 
so I'm wondering why [hp1~] needs more CPU... otherwise, iemlib's filters are 
very efficient.

Anyway, I researched a bit and found the reason why the frequency response of 
Pd filters seems 'wrong':

Miller uses a formular for calculating the cutoff frequency which is taken from 
analog filters but is not really adequate for digital filters since it doesn't 
reflect the cyclic nature of the digital domain (although you can see it in 
some articles on digital filters).

Let's take [hip~] as an example: 

the formular for a 1-pole 1-zero highpass goes:
y[n] = (x[n] - x[n-1]) * (1 + k) / 2   +   k * y[n-1]

Miller calculates the position of the pole with 
k = 1 - (fc * 2*pi / SR).

The correct formular, however (if you want the frequency response to be zero at 
Nyquist!), would be 
k = (1-sin(a))/cos(a), where a = fc * 2*pi / SR. 

You can find it here: 
http://www.arpchord.com/pdf/coeffs_first_order_filters_0p1.pdf

BTW, the reason why [hip~] seems to get stuck at 7018 Hz is because Miller 
clips the coefficient below 0, so it never reaches -1 (where the gain would be 
all zero).

Also, there is another approximation with a similiar behaviour, which goes like 
this: 
k = e^(-2*pi*fc/SR). I could find it here: http://www.dspguide.com/ch19/2.htm
Here, the pole can only move from 1 to 0 and doesn't ever reach -1 as well.

Now, is the behaviour of [hip~] 'wrong'?
If you define at 1-pole 1-zero high pass filter as something which passes 
everything at fc = DC and blocks everything at fc = Nyquist, then I'd say yes. 
If it should roughly model an analogue filter (where the cutoff frequency can 
go up to infinity) for low cutoff frequencies only, then I'd say no.

Also, as I tried to point out, this issue with the cutoff frequency is true for 
all Pd filters!

So I think this behaviour should either be changed (great, if Katja is willing 
to submit a patch!) or documented in the help patch (gain is not 0 at Nyquist!).

I'm not an engineer or any expert on filter design. It's just my two cents :-)

Christof





> Gesendet: Samstag, 15. Oktober 2016 um 11:39 Uhr
> Von: katja 
> An: "Christof Ressi" 
> Cc: pd-list 
> Betreff: Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?
>
> I'm pretty confident [hip~] would not loose its efficiency when using
> iemlib's recipe. Both hi pass filters have a feed forward and feedback
> component, with coefficients for normalization and feedback.
> Calculation of these coefficients is a bit more involved with iemlib's
> recipe, using trig functions. But coefficients aren't recalculated so
> often, therefore this difference will be negligible.
> 
> To reassure, it is not my intention to spark another 'what's wrong
> with pd' thread. If iemlib's license allows to use the recipe in BSD
> code I'll try patch the C of [hip~] and submit on the tracker for
> review. Who knows, it may be a no-brainer.
> 
> Katja
> 
> 
> 
> 
> 
> On Sat, Oct 15, 2016 at 2:34 AM, Christof Ressi  wrote:
> > There are a number of big problems with all build-in filters in Pd (expect 
> > for the raw filters).
> >
> > Problem number 1:
> > [lop~] and [hip~] both use a weird (you could also say: wrong) formula for 
> > the cutoff frequency which makes them gradually converge to a fixed output 
> > state (reached by about 7000 Hz). The same is true for [vcf~] and [bp~] 
> > with Q <= 1. Therefore the actual cutoff frequency is only correct for very 
> > low frequencies and approximately gets more and more off until it doesn't 
> > move at all.
> >
> > Problem number 2:
> > [bp~] and [vcf~] don't have zeros at DC and Nyquist. For low Q values, the 
> > slope is different for each side and changes with frequency.
> >
> > Problem number 3:
> > the gain at the center frequency is not 1 for both [bp~] and [vcf~]. It 
> > rather depends on frequency and Q. [bp~] even has has a gain of 2 for Q <= 
> > 1!
> >
> > I did some FFT plots, see the attachment.
> >
> > I remember Miller saying somewhere that these filters are not designed for 
> > high cutoff frequencies - but even for low frequencies, the behaviour of 
> > [bp~] and [vcf~] is horrible. I can see these filters are mere 
> > approximations to reduce CPU usage.
> > [hip~] is indeed much more efficient than iemlib's [hp1~], so it's well 
> > suited for DC removal (but not much else).
> > [bp~] only is a little bit more CPU friendly than iemlib's [bp2~] - but the 
> > latter one has a correct and stable frequency response.
> > [vcf~], however, is a real CPU sucker!!! 100 [vcf~] objects need 3,40% on 
> > my laptop whereas 100 of iemlib's [vcf_bp2~] only need 1,80%! But you have 
> > to consider that [vcf_bp2~] not only acts correctly but lets you set the Q 
> > at audio rate. The high CPU 

Re: [PD] deken: cannot unzip iemnet for w32

[rolfm]

hi roman

after seeing your reaction i tried again to unzip;
guess what: no hassle, no error message!!

it doesn't matter where i unzip.

i'm getting very suspicious about (my) W10,
also lot's of troubles with internet connection  and with networking.

sorry for the noise.

rolf

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Re: [PD] could vanilla borrow iemlib's hi pass filter recipe?

[katja]

I'm pretty confident [hip~] would not loose its efficiency when using
iemlib's recipe. Both hi pass filters have a feed forward and feedback
component, with coefficients for normalization and feedback.
Calculation of these coefficients is a bit more involved with iemlib's
recipe, using trig functions. But coefficients aren't recalculated so
often, therefore this difference will be negligible.

To reassure, it is not my intention to spark another 'what's wrong
with pd' thread. If iemlib's license allows to use the recipe in BSD
code I'll try patch the C of [hip~] and submit on the tracker for
review. Who knows, it may be a no-brainer.

Katja





On Sat, Oct 15, 2016 at 2:34 AM, Christof Ressi  wrote:
> There are a number of big problems with all build-in filters in Pd (expect 
> for the raw filters).
>
> Problem number 1:
> [lop~] and [hip~] both use a weird (you could also say: wrong) formula for 
> the cutoff frequency which makes them gradually converge to a fixed output 
> state (reached by about 7000 Hz). The same is true for [vcf~] and [bp~] with 
> Q <= 1. Therefore the actual cutoff frequency is only correct for very low 
> frequencies and approximately gets more and more off until it doesn't move at 
> all.
>
> Problem number 2:
> [bp~] and [vcf~] don't have zeros at DC and Nyquist. For low Q values, the 
> slope is different for each side and changes with frequency.
>
> Problem number 3:
> the gain at the center frequency is not 1 for both [bp~] and [vcf~]. It 
> rather depends on frequency and Q. [bp~] even has has a gain of 2 for Q <= 1!
>
> I did some FFT plots, see the attachment.
>
> I remember Miller saying somewhere that these filters are not designed for 
> high cutoff frequencies - but even for low frequencies, the behaviour of 
> [bp~] and [vcf~] is horrible. I can see these filters are mere approximations 
> to reduce CPU usage.
> [hip~] is indeed much more efficient than iemlib's [hp1~], so it's well 
> suited for DC removal (but not much else).
> [bp~] only is a little bit more CPU friendly than iemlib's [bp2~] - but the 
> latter one has a correct and stable frequency response.
> [vcf~], however, is a real CPU sucker!!! 100 [vcf~] objects need 3,40% on my 
> laptop whereas 100 of iemlib's [vcf_bp2~] only need 1,80%! But you have to 
> consider that [vcf_bp2~] not only acts correctly but lets you set the Q at 
> audio rate. The high CPU usage of [vcf~] seems like a bug to me...
>
> I only use the vanilla filters for the most basic stuff like DC removal and 
> smoothing. I guess these are the use cases which Miller had in mind and that 
> way [lop~] and [hip~] have their justification (although there should be some 
> more warning about the 'wrong' frequency response in the help file).
> But [bp~] and [vcf~] are almost unusable IMHO and should probably be replaced 
> by better filters in the future (while keeping the old ones for compatibility 
> reasons).
>
> Christof
>
>
>> Gesendet: Freitag, 14. Oktober 2016 um 23:51 Uhr
>> Von: katja 
>> An: pd-list 
>> Betreff: [PD] could vanilla borrow iemlib's hi pass filter recipe?
>>
>> In pd 0.47.1 [hip~] is still not perfect. Attenuation at cutoff is not
>> constant over the frequency range: -6 dB with cutoff=SR/8, -3 dB with
>> cutoff=SR/4, 0 DB with cutoff=SR/2. In contrast, iemlib's [hp1~] has
>> -3 dB at cutoff consistently.
>>
>> Could vanilla pd implement iemlib's hipass filter recipe? I don't know
>> if the license also covers the math. Documentation in
>> https://git.iem.at/pd/iemlib/tree/master points to external literature
>> for part of the math (bilinear transform). I've implemented the recipe
>> with vanilla objects for comparison, see attached.
>>
>> Katja
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Re: [PD] deken: cannot unzip iemnet for w32

[Roman Haefeli]

Hey Rolf

On Fri, 2016-10-14 at 16:38 +0200, ro...@dds.nl wrote:
> iemnet-v0.2.1~git20151118-(Windows-i386-32)-externals.zip
> 
> this version tells me i don't have perrmission to unzip.
> 
> the other: iemnet-v0.0.extended-(Windows-i386-32)-externals.zip
> gives no problem.

It was me who uploaded that package. I _believe_ I tested it on a
Windows 7 machine. Right now, I don't have access to a Windows machine
to test. All my uploads have been created the same way. Maybe you can
test whether others of the packages I uploaded by me exhibit the same
problem (osc, binfile, ggee). 

What exact error message do you get? What is the end result? Is the zip
still there, has the directory 'iemnet' been created? Where does deken
(or where do you tell deken) to extract/install it?

Roman




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