[PD] algorithms for drawing filter response curves

Mike Moser-Booth mmoserbooth at gmail.com
Wed Feb 16 00:31:43 CET 2011


Hey Hans,

Here's an update of filterview. There are now procs for the following
filters:

lowpass
highpass
allpass
bandpass
resonant
peaking
highshelf
lowshelf

I've added some lines to show the phase response (you have to comment out
line 135 and uncomment 136 to see it). I also adjust the bandwidth
calculations so the handles sit where they should (i.e. -3dB for
bandpass/notch/etc., 1/2 power for peaking/shelf).

btw, the frequency axis is log-scaled, though it could probably be improved
a little. I sort of took a Pd approach to it by making an mtof proc, so the
x-axis gets scaled to linear midi notes and converted to log-frequencies.
:-) There might be a simpler way to do it. It also doesn't go all the way
down to 0 Hz, because doing that with this approach causes the lowest
frequencies to take up too much of the graph. I think Max gets around it by
using a more compressed scale below 1-2 Hz.

.mmb

On Thu, Feb 10, 2011 at 12:39 AM, Mike Moser-Booth <mmoserbooth at gmail.com>wrote:

> Sure, I can throw the others together. Now that one is done the rest should
> fall into place pretty easily. It might take me a couple of days to get to
> it, though.
>
> .mmb
>
> On Wed, Feb 9, 2011 at 11:47 PM, Hans-Christoph Steiner <hans at at.or.at>wrote:
>
>>
>> That's awesome, thanks!  I committed it under your name:
>>
>> https://github.com/pd-projects/filterview
>>
>> I'd like to implement all of the relevant filters, which algorithms should
>> I use?  Or even better, perhaps you want to take a crack at it while I
>> figure out how to display the x/frequency on a log scale :-D
>>
>> .hc
>>
>>
>> --
> Mike Moser-Booth
> mmoserbooth at gmail.com
>



-- 
Mike Moser-Booth
mmoserbooth at gmail.com
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