could be, I know nothing really about it. But I think I've read something that stated so. And I also tried it and saw that you could inverse filters like that.
cheers 2014-04-22 21:06 GMT-03:00 Robert Esler <rob...@urbanstew.org>: > 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 along… > > Regards > > > From: Alexandre Torres Porres <por...@gmail.com> > Date: Tuesday, April 22, 2014 3:51 PM > To: GCC <rob...@urbanstew.org> > Cc: <apva...@gmail.com>, Ingo <i...@miamiwave.com>, pd-lista puredata < > pd-list@iem.at> > > 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 <rob...@urbanstew.org>: > >> 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 <por...@gmail.com> >> Subject: Re: [PD] WG: Inverse bandpass filter >> To: Ingo <i...@miamiwave.com> >> Cc: pd-list <pd-list@iem.at> >> 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 <i...@miamiwave.com>: >> >> 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: pd-list-boun...@iem.at >> > [mailto:pd-list-boun...@iem.at<pd-list-boun...@iem.at>] >> Im Auftrag >> von >> > AP Vague >> > Gesendet: Freitag, 18. April 2014 18:49 >> > An: pd-list@iem.at >> > 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~]? >> >> >> _______________________________________________ >> Pd-list@iem.at mailing list >> UNSUBSCRIBE and account-management -> >> http://lists.puredata.info/listinfo/pd-list >> >> >
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