thanks everyone ... Alexandre that is just what i was looking for
On 6 May 2014, at 06:09, Alexandre Torres Porres wrote: > I did one and shared on the list > > you can check it > at:https://drive.google.com/file/d/0B3AoiT0xk8fnNU9PRHdldVVFbU0/edit?usp=sharing > > > 2014-05-05 16:41 GMT-03:00 katja <katjavet...@gmail.com>: > Brute force time domain convolution for small kernel can be done with > [fexpr~]. For zero phase filter kernels, fast convolution in Pd is > relatively simple. Multiply real and imaginary part of the signal's > spectrum with the filter's spectrum while using four times overlap and > Hann windowing before FFT and after IFFT, and normalize. Pd's FFT > routines assume x[0] at the start of the filter kernel, not at the > center, so you have to rotate your zero phase filter kernel before > taking it's Fourier Transform. > > Katja > > On Mon, May 5, 2014 at 8:49 PM, david medine <dmed...@ucsd.edu> wrote: > > For the FFT based convolution, you could easily modify the example patch > > I06.timbre.stamp.pd to do straight up convolution in the frequency domain. I > > wouldn't know how to do it in the time domain without an extern or a lot of > > painstaking work. It might be a nice thing to have, though. > > > > I can tell you, though, that the frequency domain method will out perform > > the time domain in terms of CPU usage. But, since you are windowing there > > will be a latency. Apart from that, the output is identical by both methods. > > > > y(n) = x(n) * g(n) > > Y(k) = X(k)G(k), y(n) = IDFT(Y(k)) > > > > where g(n) is the impulse response, X(k) is the discrete Fourier transform > > of x(n) and * is the convolution operation. > > > > > > On 05/05/2014 09:33 AM, Oli Larkin wrote: > >> > >> hi, > >> > >> is anyone aware of an example of both a brute force time domain (e.g. > >> buffir~ in Max) and an FFT-based fast convolution patch in pd-vanilla? I > >> would like to do a comparison of the two. Can be using a small IR, just for > >> demo purposes. > >> > >> cheers, > >> > >> Oli > >> > >> _______________________________________________ > >> Pd-list@iem.at mailing list > >> UNSUBSCRIBE and account-management -> > >> http://lists.puredata.info/listinfo/pd-list > > > > > > > > _______________________________________________ > > Pd-list@iem.at mailing list > > UNSUBSCRIBE and account-management -> > > http://lists.puredata.info/listinfo/pd-list > > _______________________________________________ > Pd-list@iem.at mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list > > _______________________________________________ > Pd-list@iem.at mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list _______________________________________________ Pd-list@iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
