[linux-audio-dev] idea: wavelets of variable frequencies

Fons Adriaensen fons.adriaensen at skynet.be
Thu Jun 19 18:58:01 UTC 2003

On Thu, Jun 19, 2003 at 11:23:07PM +0200, Tom Weber wrote:
> Instead of doing a discrete fourier transform when reading a small
> frame of the sound, do a dense transform (every 0.1 Hz?) and pick out
> the peaks. Then assume that a similar enough frequency in the next
> frame comes from the same source, keep joining those and your sound
> will be represented by a lot of oscillators (wavelets) with amplitude
> and frequency curves. I guess this would overcome the weaknesses in
> having fixed frequencies.

There may be some problems...

- What about noise-like signals ? 

- For a resolution of 0.1 Hz you need 10 seconds of sound. Only a real
  sine wave lasting the whole 10 s will tranform as a 'peak', everything
  else will be smeared out.  

The normal way to use wavelets is to make them shorter at high frequencies,
sort of DFT with a log frequency scale.

> This idea shouldn't be new, where can I read about it? Has it been
> implemented anywhere?

There are lots of resources on wavelets on the web. Ask google.


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