Fast Coarse Spectrum Analysis of Sound Samples in Java
in [DSP]
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From: Vladimir Vassilevsky on 9 Aug 2010 14:42 John David Eriksen wrote: > On Aug 9, 6:29 am, Vladimir Vassilevsky <nos...(a)nowhere.com> wrote: > >>John David Eriksen wrote: >> >>>When I'm done analyzing a chunk of sound, I want the following >>>information. I want the average amplitude of the energy at the given >>>frequency bands over the length of the sound sample expressed as a >>>floating-point value between 0 and 1.0: >>>I'm looking for something quick and dirty that can execute quickly. >> >>Use a simplest zero crossing period counter. >>Make a hystogram of half-periods. >> > Thanks for your help. Correct me if I am wrong, but doesn't zero > crossing information fail to give me any information about amplitude? FWIW, the relation of the different columns in the histogram gives you the relative estimate of energies at the corresponding frequencies. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
From: John David Eriksen on 10 Aug 2010 12:16 On Aug 9, 10:49 am, jacko <jackokr...(a)gmail.com> wrote: > high pass the top half of your spectrum and measure the range min,max. > square your residual and repeat for an octave division... normalize > outputs to approximate unit range. > > Not as quick as Vlad's but will be different. > > Cheers Jacko Hey Jacko, Thanks for your suggestion. Much of your terminology is unfamiliar -- it looks like I have quite a bit to learn. I have access to FFT libraries, but it looks like I have to perform operations on my data once I have it in the frequency domain that may not be supported by available Java libraries. It looks like I'm either going to have to hit the books or keep searching around for well-documented and ready-made software packages that can help me out. Thanks again, John David
From: Ron N. on 10 Aug 2010 15:05
On Aug 9, 5:29 am, Vladimir Vassilevsky <nos...(a)nowhere.com> wrote: > John David Eriksen wrote: > > When I'm done analyzing a chunk of sound, I want the following > > information. I want the average amplitude of the energy at the given > > frequency bands over the length of the sound sample expressed as a > > floating-point value between 0 and 1.0: > > I'm looking for something quick and dirty that can execute quickly. > > Use a simplest zero crossing period counter. > Make a hystogram of half-periods. Yet another option similar to this is to create a histogram of the times between local maxima/minima inflection points; or a 2D histogram using both time and delta amplitude between these local extrema points. -- rhn A.T nicholson d.0.t C-o-M http://www.nicholson.com/rhn/dsp.html |