Cycling 74 » Topic: FFT~ Frequency Based Beat Analysis http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/feed Wed, 19 Jun 2013 11:58:48 +0000 http://bbpress.org/?v=2.2.4 http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-47200 <![CDATA[FFT~ Frequency Based Beat Analysis]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-47200 Mon, 14 Dec 2009 17:48:55 +0000 ComfortableInClouds Hi, I am developing a frequency based beat analyzer using the fft~ object. i’ve taken my first steps by grouping the bands into 16 different groups then finding the average power in each of those groups using a leaky integrator. i find that i am getting average amplitude values exceeding 1, how is this possible? Here is my patch, it requires the CNMAT accumulate~ external, which can be found here:

http://cnmat.berkeley.edu/downloads

– Pasted Max Patch, click to expand. –

thanks!

]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-169708 <![CDATA[Re: FFT~ Frequency Based Beat Analysis]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-169708 Mon, 14 Dec 2009 19:35:35 +0000 Jean-Francois Charles Look at MSP tutorial 26, 3rd “Technical Detail”, to know more about the max value that you can get in a FFT bin (amplitude – polar representation).

]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-169709 <![CDATA[Re: FFT~ Frequency Based Beat Analysis]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-169709 Mon, 14 Dec 2009 22:23:03 +0000 ComfortableInClouds thanks jean, that cleared things up.

]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-169710 <![CDATA[Re: FFT~ Frequency Based Beat Analysis]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-169710 Tue, 15 Dec 2009 00:57:29 +0000 ComfortableInClouds in that technical detail description, what is meant exactly by “sum of points in the window”? does that mean, for example, 1 + 2 + 3 … + 511 + 512 if the window size is 512 samples? Is there any kind of sigma object in Max to do this calculation?

]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-169711 <![CDATA[Re: FFT~ Frequency Based Beat Analysis]]> http://cycling74.com/forums/topic/fft-frequency-based-beat-analysis/#post-169711 Tue, 15 Dec 2009 03:20:20 +0000 Jean-Francois Charles “sum of points in the window” seems to mean “number of points in the window”, in the given example, 512. Actually, “number of points in the window/hop size” is equivalent to “overlap”. In the given example, 512/sqrt(2) = 362…

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