[CLAM] ClamExtractorExample LowFreqEnergyRelation

vincenzo.dimattia vincenzo.dimattia at libero.it
Mon Feb 25 10:11:00 PST 2008

Dear David thanks a lot for your help. My final project consists on an automatic audio segmentation system which I have implemented in matlab modifying the Alexander Haubold’s Matlab resources [http://www.aquaphoenix.com/research/matlab/]. The modified program requires as input the audio file (wav) and the CLAM XML file. In order to interface Matlab with CLAM I used an XML parser which is able to extract the values of the MFCC descriptor from the CLAM XML file. In particular I used XMLTree an XML toolbox for Matlab [http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=1757&objectType=file].
Thanks again
Best regards

---------- Initial Header -----------

>From      : "David García Garzón" dgarcia at iua.upf.edu

To          : clam at iua.upf.edu
Cc          : "vincenzo.dimattia" vincenzo.dimattia at libero.it,"clam" clam at iua.upf.edu
Date      : Mon, 25 Feb 2008 15:16:41 +0100
Subject : Re: [CLAM] ClamExtractorExample LowFreqEnergyRelation

> On Monday 25 February 2008 12:25:24 vincenzo.dimattia wrote:
> > Dear all,I am Vincenzo Dimattia, I am developing my final project, an
> > automatic segmentation system,and I am using the programm
> > ClamExtractorExample for the extraction of the audio descriptors . I would
> > like to know how is calculated the LowFreqEnergyRelation.This should be
> > higher for low frequency signal and lower for high frequncy signal. Is it
> > right? Thanks
> > Vincenzo Dimattia
> Hi, Vincenzo.
> There was an error on doxygen description. LowFreqEnergyRelation had the 
> description of MaxMagFreq. I just fixed it on the svn. The description for 
> LowFreqEnergyRelation is now this one:
> "Ratio between the energy over 0-100 Hz band and the whole spectrum energy.
> To avoid singularities while keeping descriptor continuity, when the whole 
> spectrum energy drops bellow $10^{-4}$, such value is considered as whole 
> spectrum energy."
> So you are right with your interpretation. But keep in mind that 0-100 Hz is a 
> very narrow band and it is used to spot bass sounds. If you are interested in 
> locating high frequencies, HighEnergyContent is more appropiated. It is 
> defined as:
> "Sum of the squared spectrum magnitude multiplied by the wave number of the 
> bin. It is pretty similar to the derivative of the energy, or a high pass 
> filter, which gives higher values for high frequency content."
> We would be glad if you report back to the mailinglist your progress with your 
> final project :-) And, please, consider also integration of your work into 
> CLAM code base. Integration into a big existing project is often appreciated 
> by evaluators. Just drop us a line if you want to.
> David.

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