[PD] convolution using pd-vanilla
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
Re: [PD] convolution using pd-vanilla
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
Re: [PD] convolution using pd-vanilla
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
Re: [PD] analog PD+GEM
Jeenyoos! BTW I went to a modular synth meetup the other day. Hoxtonowl were demoing a eurorack module that runs Pd. They already have an effects pedal that uses it: http://hoxtonowl.com/2014/04/owl-puredata-alphatesters-wanted/ Ninja Jamm - a revolutionary new music remix app from Ninja Tune and Seeper, for iPhone and iPad http://www.ninjajamm.com/ Gemnotes-0.2: Live music notation for Pure Data, now with dynamics! http://sharktracks.co.uk/ On Thursday, 17 April 2014, 18:12, Chris Clepper cgclep...@gmail.com wrote: I played a bit with it at last year's AHNE meet. It was perplexing to use even for someone with extensive video and Eurorack experience! I think it is still just the one-off module. Crazy device though.. On Thu, Apr 17, 2014 at 12:09 PM, Dan Wilcox danomat...@gmail.com wrote: Hehe https://www.youtube.com/watch?v=63ay74S34XI Dan Wilcox @danomatika danomatika.com robotcowboy.com ___ 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
Re: [PD] convolution using pd-vanilla
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
