Though with DC you don't have the issue of phase. I'm not an expert in filter math, but I assume that by the time your filtered audio (assuming its not DC) gets subtracted by the [-~] object it is out of phase with the original signal. Moreover, I hear a distinct difference. Maybe I'm not conceiving your statement properly and perhaps this discussion has been about DC all alongĀ
Regards From: Alexandre Torres Porres <[email protected]> Date: Tuesday, April 22, 2014 3:51 PM To: GCC <[email protected]> Cc: <[email protected]>, Ingo <[email protected]>, pd-lista puredata <[email protected]> Subject: Re: [PD] WG: Inverse bandpass filter can;t remember where I saw about this, but check this link http://msp.ucsd.edu/techniques/v0.11/book-html/node141.html see the quote "An easy and practical way to remove the zero-frequency component from an audio signal is to use a one-pole low-pass filter to extract it, and then subtract the result from the signal. The resulting transfer function is one minus the transfer function of the low-pass filter:" doesn't it agree with what I said? cheers 2014-04-22 14:37 GMT-03:00 Robert Esler <[email protected]>: > I could be wrong, but I don't think it's quite the same thing. I believe the > signal would be out of phase negating many of the effects of the filter. I > would recommend using [biquad~] and in pd-extended there is a [notch] object > which takes care of the coefficients. This sounds much cleaner and more > notch-like to my ear than subtracting the filtered output. > There is an explanation in Miller's book if you like unit circle math: > http://msp.ucsd.edu/techniques/latest/book-html/node144.html > ----------- > Message: 4 > Date: Tue, 22 Apr 2014 01:59:07 -0300 > From: Alexandre Torres Porres <[email protected]> > Subject: Re: [PD] WG: Inverse bandpass filter > To: Ingo <[email protected]> > Cc: pd-list <[email protected]> > Message-ID: > <caeasfmhd0hanlmv9vutcsqzjkzy69i7wmebqq+20s2riwya...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > isn't it just subtract the audio from the filtered output? > > I guess you can get inverse freq response just by that > > cheers > > > 2014-04-18 17:21 GMT-03:00 Ingo <[email protected]>: > >> You could send the original signal in parallel and invert the phase by >> multiplying with -1. You might have to delay the original signal in case >> that the processed signal gets also delayed by one or more blocks. >> >> Ingo >> >> _______________________________________ >>> > Von: [email protected] [mailto:[email protected]] Im Auftrag >> von >>> > AP Vague >>> > Gesendet: Freitag, 18. April 2014 18:49 >>> > An: [email protected] >>> > Betreff: [PD] Inverse bandpass filter >>> > >>> > Is there a simple way to make [bp~] or [vcf~] have an inverse function? >> To >>> > filter out, rather than pass a changing frequency value. Is the easiest >>> > way to do this with a combination of [lop~] and [hip~]? >> >> >> _______________________________________________ >> [email protected] mailing list >> UNSUBSCRIBE and account-management -> >> http://lists.puredata.info/listinfo/pd-list >>
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