[PD] can [bp~] be obtained with biquad coefficients?

IOhannes m zmoelnig zmoelnig at iem.at
Mon Apr 14 09:25:42 CEST 2014


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On 2014-04-12 08:45, Alexandre Torres Porres wrote:
> { t_sample output =  *in++ + fb1 * last + fb2 * prev; if
> (PD_BIGORSMALL(output)) output = 0; *out++ = ff1 * output + ff2 *
> last + ff3 * prev; prev = last; last = output; }
> 
> Well, I made a silly confusion mistake and thought the first line
> was feedforward  (and then equivalent to the bp~). But still, it
> could be it for all I can tell. How can you actually see wether is
> feedback or not?

stupid way: the coefficients are called "fb1" and "fb2"; "fb" is an
abbreviation for "feedback", so this might have put you onto the right
track.

complicated way: "last" and "prev" refer to past output samples (as
has been mentioned in other emails), and using old output to generate
new output is the definition of feedback.


fgmasdr
IOhannes
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