Re: help at octave dot org

[Schloegl Alois]

WAV-files can be read and stored with BIOSIG (http://biosig.sf.net).

### load file
[signal,HDR]=sload('source.wav');
### signal contains the time domain signal
### HDR contains the header information - do not modify unless you know what you
do.

### here you need to apply your filters
### maybe somebody else can help

### saving file
H2 = HDR; H2.FileName = 'target.wav';
H2 = ssave(H2,signal);


Alois




   for some help if some of you can give me a source code in octave that
   does the following tasks.

   1.) first the program would load a wav file.

   2.) if i'm not mistaken, the wav file is in time-domain format. it
   needs FFT (fast fourier transform) for it to be in the frequency domain.

   3.) it then passes through a notch filter which filters out the
   noise. the noise is the hissing sound you hear when you play cassette tapes
   or old records. the output is then converted back to a wav file.

   This project is actually for an audio filter for old records. first
   we need to figure out the frequency of the "hissing" sound so that we
   can remove it using the notch filter.

I think you are in for more than you bargained for. The hissing that
you refer to is not a single frequency that would be taken out by a
notch filter--rather, it's a pink, broadband noise that you'd need a
low-pass filter for. Such filter probably should be adaptive. SoX
actually has some pop/click/noise removal tools.

You can read about some techniques used for removing audio flaws
from analog recordings in http://www.webdevelopersjournal.com/studio/dart.html




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